CN100534538C

CN100534538C - Method for preparing double continuous structure microporous stent material

Info

Publication number: CN100534538C
Application number: CNB2006101665614A
Authority: CN
Inventors: 李世荣; 陈哲; 陈曦
Original assignee: Wuhan Institute of Technology
Current assignee: Wuhan Institute of Technology
Priority date: 2006-12-31
Filing date: 2006-12-31
Publication date: 2009-09-02
Anticipated expiration: 2026-12-31
Also published as: CN101002963A

Abstract

A porous scaffold material with dual-continuous millipore structure for benifiting the cell growth and guiding tissue regeneration is prepared through adding polymer in an organic solution N, N-dimethyacetylamine or the mixture of N, N- dimethylacetylamine and tetrahydrofuran, heating for dissolving, ageing at 0-95 deg.C, freezing at -200-0 deg.C to obtain gel, extracting in the extracting solvent at -100-0 deg.C, and vacuum drying.

Description

The preparation method of the porous support materials of micropore bicontinuous structure

Technical field

The invention belongs to biomedical materials field, relate to a kind of preparation methods that can be used for cell growth support or guide tissue regeneration particularly.

Background technology

Nineteen ninety, people such as De Ponti have prepared biodegradable polyalcohols acid (as PLLA, PDLLA, PGA and PLGA) timbering material by the gas foaming process ^[1]

1992, A.G.A.Coombes and J.D.Heckman ^[2,3]Prepared porous support materials by the gel casting technique.They are dissolved in acetone formation concentration with hypocrystalline PLLA under 46～52 ℃ be the solution of 7% (w/v), under room temperature (22～24 ℃), leave standstill 30min, obtain the bigger gel of intensity, then gel is soaked to remove in three days in methanol and desolvate, constant pressure and dry under the room temperature promptly gets the irregular loose structure of aperture＜5 μ m; They also under 52 ℃ with the mixture of PLLA and PLGA50 (25: 75, wt) be dissolved in the acetone that to form concentration be the solution of 24% (w/v), leave standstill 24h under the room temperature, then gel was immersed in the methanol three days, immersed again in the water four days, constant pressure and dry under the room temperature obtains the irregular porous structure material of aperture＜2 μ m.

1993, Mikos A.G. etc. ^[4]Propose first the PGA fleece to be bondd, obtain porosity and be 81% porous support by heat treatment process.Mikos A.G. etc. immerse the PGA fleece in the chloroform solvent of PLLA, treat on the fusing point of zone heating to two kind of polymer after the solvent evaporates, the PGA fiber is bonded together in its intersection, select a kind of solvent that can only dissolve PLLA that it is dissolved then, can obtain porous network structure.

1994, Mikos A.G. etc. ^[5]Propose again with salt particle to prepare the PLLA perforated membrane by porogen leaching technology, the so-called solution-cast of this method/particle leaching technology (solution casting/particulate leaching) as porogen.Just a certain amount of garbled salt particle (NaCl, sodium tartrate or sodium citrate) is joined in chloroform (or dichloromethane) solution of PLLA, be poured on the culture dish after stirring is uniformly dispersed particle.Mixture is evaporated 48h remove and to desolvate, vacuum drying 24h removes residual solvent under 0.1mmHg, 25 ℃ of conditions then.The PLLA/ salt mixture is soaked 48h remove salt particle in 25 ℃ of distilled water, dry 24h under normal pressure continues dry 48h under 0.1mm Hg condition again.The product of specific degree of crystallinity can be heated to the PLLA/ salt mixture that removes after desolvating more than the fusing point of PLLA if desired, obtains the sample of different crystallinity then by annealing or quenching process.During by the method for preparing porous material, the rate of removing of salt can reach 99.9%, and the porosity of film is up to 93%, and mean pore sizes can reach 150 μ m.

Nineteen ninety-five, K.Whang ^[6]Deng utilizing the emulsion Freeze Drying Technique to prepare the PLGA porous support.PLGA (85/15) is dissolved in the dichloromethane, add a certain amount of ultra-pure water, stirring makes it form uniform emulsion, putting into liquid nitrogen quenches, then under-55 ℃, 30mTorr condition vacuum drying remove desolvate and at room temperature vacuum drying remove residual solvent, obtain the support that the hole height is communicated with.By the adjustment process parameter, as the volume fraction of water, the mass fraction of polymer and the molecular weight of polymer etc., can obtain average pore size be higher than 90% in 15～35 mu m ranges (macropore diameter is greater than 200 μ m), porosity, than hole area at 58～102m ²g ^-1The support of scope.

1996, D.J.Mooney etc. ^[7]Propose the PGA nonwoven web to be bondd, obtain porous tubular structured by the method for spraying (spray casting).They are centered around the PGA nonwoven web on the politef cylinder and form tube, sew up the border.PLLA and PLGA are dissolved in chloroform respectively and form certain density solution, are that carrier sprays on the PGA fleece of rotation with nitrogen with solution.Spraying is removed residual solvent with the prefabricated pipe lyophilization after finishing, and sheds the politef cylinder then, can obtain porous support.The dissolubility of PGA in chloroform is very low, and therefore the PGA fiber form remains unchanged substantially in this course.

The same year, D.J.Mooney etc. ^[8]Propose with CO again ₂Gaseous matter prepares the PLGA porous support as porogen, and this method can be avoided with an organic solvent, prevents residual organic solvent pair cell toxigenicity in the support; And CO ₂Nontoxic, inexpensive, stable in properties, pollution-free, economically valuable.They are pressed into lamellar with the PLGA powder, at the CO of room temperature, 5.5MPa ₂The middle 72h that soaks into reduces to normal pressure then, is dissolved in the CO in the polymer ₂Rapid nucleating growth has formed that the aperture is about 100 μ m, porosity is higher than 93% porous support.But this method also has certain defective: external morphology that can not accurate control support, have closed hole to exist, the type of polymer is had certain restriction---can only use amorphous polymer, this is restricted when the higher support of processing machinery intensity.

Ch.Schungens etc. ^[9,10]Utilize solid-liquid phase detachment technique and liquid-liquid phase separation technology in the thermal induction phase detachment technique to prepare fine-celled foam first.They are dissolved in a certain amount of PDLLA and PLLA in the dioxane respectively, form to immerse quench in the liquid nitrogen 2h, vacuum (about 10 in ice/water-bath of 0 ℃ then behind the clarifying polymer solution rapidly ^-2Torr) be dried to no dioxane after, be warming up to room temperature vacuum drying 24h again.Perhaps polymer is dissolved in the mixture of a certain proportion of dioxane/water, forms after the clear solutions 20 ℃ of constant temperature 30min more than cloud point, identical with said process then, obtain porous support through steps such as quenching, lyophilization and vacuum dryings respectively.When making solvent with pure dioxane, polymer solution generation solid-liquid is separated, and the aperture of gained porous material is at 10～100 mu m ranges, and porosity is up to 91%.During with the mixture as solvent of dioxane/water, liquid-liquid phase separation takes place, the aperture of gained porous material is at 1～10 mu m range, and porosity is up to 93%.

P.van de Witte etc. ^[11]Utilize non-solvent to induce phase detachment technique to prepare the PLA perforated membrane, and studied the polylactic acid crystallization process for the formation of film and the influence of form.The PLA that L-lactic acid is different with D-lactic acid mol ratio (poly-L-95/D5-lactic acid, PLA95; Poly-L80/D20-lactic acid, PLA80; Poly-L-50/D-50-lactic acid, PDLLA) be dissolved in respectively and form solution in the chloroform, solution casting on doctor blade and immerse in the methanol, is kept removing in 3 days in 22 ± 2 ℃ methanol and desolvates, and normal pressure dry 1 day down, vacuum drying were removed poor solvent methanol in 1 day then.The slowly crystallization of PLA80 solution, and PDLLA is uncrystallizable, has only the fast polymer of crystallization rate (PLA95 and PLLA) just can obtain the film of stable in properties.The film of low concentration PLLA formulations prepared from solutions is alveolate texture, and the film of highly concentrated solution preparation is porous microsphere shape structure.They have also studied the character of the polylactic acid membrane of preparation in other solvent-nonsolvent system (dioxane-water, N-Methyl pyrrolidone-water and dioxane-methanol), wherein polylactic acid-N-Methyl pyrrolidone-aqueous systems settling velocity is the fastest, and the film character that obtains is the most stable ^[12]

1997, Park Y.J. etc. ^[13]Utilize the constant pressure and dry phase-inversion technologies to prepare the PLLA perforated membrane.PLLA is dissolved in the mixture of dichloromethane-ethyl acetate, is poured into then in the PGA mesh grid, constant pressure and dry gets final product.Three-component polymer solution (PLLA-dichloromethane-ethyl acetate) forms the PLLA perforated membrane by solvent evaporation, and the PGA fleece that supports the PLLA film plays an important role when forming surface holes.

The same year, P.M.Kaufmann etc. ^[14]By adopting and Mikos A.G. ^[5]Identical method is that porogen leaching technology has prepared the PLLA porous support, and the average pore size of gained support is that 180 μ m, porosity are up to 95%.

K.F.Leong etc. ^[15](rapidprototyping, RP) (3-dimensional printing 3DP) has prepared the method for PLGA porous support to the 3 D-printing technology in by rapid shaping technique to have introduced Kim in 1998 etc. in its survey article.Rapid shaping technique claims solid free forming technology (solid free-form again, SFF), be at first to utilize CAD system to make the threedimensional model of support according to the shape of required support, again by date processing with a series of two dimensional surface models of the transversal one-tenth of threedimensional model, the repeated deposition of the material layer that computerizeds control and method for processing prepare the technology of 3D support.The PLGA solution that Kim etc. will contain the salt grain injects " printer ", " printer " scans according to the shape of areal model, polymeric material is successively solidified, finally forming diameter by the two-dimentional thin layer that progressively superposes is that 8mm, height are the cylindrical stent of 7mm, after leaching the salt grain, the aperture of support is at 45～150 μ m, and porosity is 60%.

1998, Harris LD etc. ^[16]Gas foaming technology and porogen leaching technology combined prepared the PLGA porous support.The compound shortcoming that is intended to avoid various unitary system Preparation Methods of this research method.Harris LD etc. mix PLGA and granular NaCl, and room temperature depresses to lamellar, at high pressure CO ₂In soak until balance, reduce to behind the normal pressure sample immersed and leach the NaCl granule in the distilled water, can obtain porous support.The big I of ratio by telomerized polymer/salt grain and salt grain changes the connectedness in porosity, aperture and the hole of polymer support.

Yoshiaki Kawashima etc. ^[17]Utilize new emulsifying agent dispersion technology (novel emulsion solvent diffusionmethod) in two kinds of different disperse medium (water and oil), to prepare the PLGA Nano microsphere of load peptide (peptide) (TRH and elcatonin), wherein in oil, to carry out Nano microsphere performance the best of emulsified solvent process for dispersing preparation.Concrete preparation method is: PLGA and a certain amount of medicine are dissolved in acetone, methanol and dehydrating sorbitol monooleate (Span80) mixture, again polymer-drug solution is poured into and contained 2% (w/w) ricinoleic acid glyceride (HGCR, Hexaglycerincondensed ricinoleate) sad and capric acid triglyceride (caprylate and caprate triglyceride, TriesterF-810) in, stir fast and make its emulsifying, carry out centrifugalize then.With precipitate washing precipitation in normal hexane, polyvinyl alcohol water solution and distilled water successively, at last with the precipitate lyophilization, can obtain average diameter is the Powdered Nano microsphere of 700nm again.

Markus S.Widmer etc. ^[18]Binding soln casting and extruding technology (extrusion technique) have prepared PLGA and PLLA pipeline.At first utilize the solution-cast technology to prepare that polymer (PLGA75 or PLLA)/(method is with Mikos A.G. for salt (NaCl) mixture disk ^[5]).The mixture disk is put into specific extrusion device, heat under the temperature of setting, extrude the PLLA/ salt mixture behind the 8min or extrude the PLGA/ salt mixture behind 20min, the control extrusion pressure makes rate of extrusion at 10mms ^-1The internal diameter of gained pipeline is 1.6mm, and external diameter is 3.2mm.Leach salt grain after drying, can obtain the structure of open bore.The open aperture that so obtains is at 150～300 mu m ranges, and the material porosity reaches 83%.

1999, Y.S.Nam and T.G.Park ^[19,20](thermally induced phaseseparation) prepared PLGA, PLLA and PDLLA porous foam with the thermal induction phase detachment technique.In the dioxane/aqueous systems of different proportion, respectively in liquid nitrogen and-15 ℃ of coolings (quenching) fast down, the ratio of research polymer type and concentration, solvent/non-solvent and hardening heat are to the influence of bracket holes structure then with polymer dissolution for they.By changing hardening heat scalable coarsening process, obtained having the support of open architecture, the aperture of macropore surpasses 100 μ m in the support.Slowly cooling amorphous polymer (PDLLA and PLGA) can obtain open macroporous structure, and the aperture mainly is distributed between 20～170 μ m, and porosity reaches as high as 90.3%; And cool off semi-crystalline polymer (PLLA) fast, and obtaining closed microcellular structure, the aperture mainly is distributed in about 3 μ m.The support that will have open macropore is used for load recombinant human growth hormone, and (recombinant human growth hormone, rhGH), support shows good performance for sustained release rhGH.They also by before quenching with polymer solution in the following ageing of cloud point temperature, obtain average pore size and reach as high as 92% fine-celled foam in 1～30 μ m, porosity.In addition, add surfactant (polyethylene glycol-propylene glycol-Polyethylene Glycol, Pluronic F127), can make the aperture increase to 50 μ m, and make Kong Gengyuan, connective better.

The same year Peter X.Ma and Ruiyun Zhang ^[21]Also the method for utilizing the thermal induction phase detachment technique to prepare porous material is studied.They are dissolved in PLLA, PLGA85 and PDLLA heating in the oxolane respectively, stir 2h at 60 ℃ and obtain uniform solution.Solution rapid cooling after 50 ℃ of preheatings is made its gelation, and keep 2h at gelling temp.Place distilled water to extract solvent gel then, and at-18 ℃ of freezing 2h, drier 1 week of vacuum (0.5mmHg) in-5～-10 ℃ cryosel is bathed.Make three-dimensional continuous poriferous network structure, fiber diameter range is 50～500nm, and porosity is up to 98.5%.

Hideki Murakami etc. ^[22]Utilize improved spontaneous emulsification agent dispersion method (modified spontaneousemulsification) to prepare the PLGA nano-particle.PLGA is dissolved in acetone-dichloromethane-ethanol (or methanol) mixture, in solution, adds polyvinyl alcohol water solution then, stir and make its formation emulsion, add the pure water ultrafiltration again three times, carry out lyophilization at last and get final product.

2000, Y.Senuma etc. ^[23]Use eddy-current disc nebulizer (spinning disk atomization) preparation PLA porous support first, the aperture is at 100～400 mu m ranges.The eddy-current disc nebulizer of this non-commercial use is made up of peristaltic pump, motor, disk and temperature control equipment.With peristaltic pump polymer solution is squeezed in the disk, with hot-air the disk temperature is remained on more than 100 ℃, drop flows to bottom of device from disk, drop is cooled to-10 ℃ in the bottom with liquid nitrogen, collects the drop of required size.Evaporation removes and desolvates, and can obtain porous microsphere.

David D.Hile etc. ^[24]Utilize supercritical CO ₂Prepare the PLGA porous support, and studied the ability of support release active growth factor.PLGA is dissolved in the certain density solution of formation in the dichloromethane, adds the phosphate buffer (PBS) that contains fibroblast somatomedin (bFGF) and bovine serum albumin (BSA) then.Mixture is put into the ultrasonic degradation device be processed into uniform emulsion, inject from molding jig, adding pressure is that 80bar, temperature are 35 ℃ CO ₂, under this pressure, keep 24h so that extract dichloromethane and allow CO in the polymer ₂Reach capacity.Blood pressure lowering fast can obtain the porous polymer foam then.Active bFGF discharges with constant relatively speed on foam.Use supercritical CO ₂Can shorten polymer greatly at CO ₂In infiltrating time, enhance productivity, yet, directly pass through CO ₂The amount of residual solvent has surpassed the regulation of U.S. medicine inspection office when removing dichloromethane, need take measures further to remove to desolvate.

Lichun Lu etc. ^[25]With PLGA85 and PLGA50 is that raw material, NaCl are porogen, by solution-cast one particle leaching technology ^[5]Prepare the PLGA porous foam of different shape, and studied various foams degradation property in vitro and in vivo.The content of finding PGA among the PLGA has appreciable impact to foamy degradation property.And because the autocatalysis of catabolite, it is fast that the foamy vivo degradation speed ratio of PLGA50 external degradation speed is wanted.

Y.S.Nam etc. ^[26]With carbonate is porogen, adopts the chemical blowing process in the gas foaming technology to prepare the PLLA porous support.They are with NH ₄HCO ₃Uniform particles is dispersed in the PLLA-solvent gel, then mixture is put into hot water and makes NH ₄HCO ₃Decompose and generate ammonia and CO ₂, can obtain connective good porous support, the aperture of support is 300～400 μ m.In the hepatocyte implant frame with Mus, cell viability improved 40% after survival rate reached 95%, 1 day.

Except inorganic salt, also the available water soluble polymer is as the porogen of preparation porous support.Tsuji Hideto etc. ^[27]Just once PLLA and water-soluble poly ethylene oxide (PEO) mixture were dissolved in dichloromethane and poured into a mould film forming, after the solvent evaporation, water leaches PEO and obtains the PLLA perforated membrane.Reduce with the increase of PLLA mass fraction in the aperture of perforated membrane, increases with the increase of PEO molecular weight.

In order further to promote the absorption of cell, the transmission and the neoblastic growth of material, Ruiyun Zhang and Peter X.Ma ^[28]Prepared PLLA macropore support with homemade sugared porogen with certain three dimensional structure.The preparation method of porogen is as follows, and the sugar grain is heated to fusing fully under 120～130 ℃, picks fused sugar and drawing fiber shape with blade, and fiber is solidified, and makes fibre diameter at 100～500 mu m ranges by the control draw speed.Sugared fiber is put into certain shape, can obtain testing required porogen.The preparation method of porous support is, certain density PLLA/THF solution is splashed in the porogen, and the freezing at a certain temperature solution that makes forms gel, extracts solvent and porogen with distilled water then, carry out freezing and lyophilization again, can obtain having the PLLA porous support of specific modality.

Calendar year 2001, people such as Peter X.Ma ^[29,30]The paraffin microsphere of using molding bonded has again prepared the PLLA porous support as porogen.Fused paraffin is poured in polyvinyl alcohol (PVA) solution, obtained the wax ball with dispersive method.The wax ball of certain particle diameter is put into plastic bottle, push down upper surface,, make wax ball bonding form inner mutual successive model at 37 ℃ of heating bottle 40min with flat board.After treating that the bottle temperature is reduced to room temperature, (1: 1, v/v) solution rapidly heated 2～3min then so that remove air in the dewax pelletizing under 250mmHg, about 37 ℃ of conditions dropwise to add dioxane/pyridine of PLLA in the wax pelletizing.One night polymer solution was separated-70 ℃ of placements polymer/wax pelletizing, gel/wax ball mixture with phase-splitting soaks in cyclohexane extraction respectively except that desolvating and the wax ball then, the reuse cyclohexylamine extracts cyclohexane extraction, and gel carried out freezing and lyophilization, can obtain having the nanofiber extracellular matrix of mutual successive spherical pore structure.

Zhuo Xiong etc. ^[31](precise extrusion manufacturing) prepared the PLLA porous support with the accurate stretching technique in the rapid shaping technique.Go out three-dimensional data with the CAD software design, the PLLA injection is heated to 160 ℃ extruding jet and all keeps 160 ℃ in whole forming process.Before forming process, earlier PLLA is kept 30min in shower nozzle, so that obtain uniform semi liquid state PLLA.Move by computer control shower nozzle, with fused polymer-extruded and be piled into required three dimensional structure.The PLLA support aperture of preparation can be controlled at 200～500 mu m ranges;

Arnaldo R.Santos etc. ^[32]With the sodium citrate is porogen, has prepared the PLLA perforated membrane with porogen leaching technology, and it has been carried out biological assessment.According to the difference of salt grain particle diameter, obtain the film of three kinds of apertures (＜45 μ m, 180～250 μ m and 250～350 μ m), porosity is about 80%.The testing in vitro result shows that various PLLA films are promoting all to show similar performance aspect extracellular matrix (as IV type ossein and the Fibronectin) growth.

Jun Jin Yoon and T.G.Park ^[33]Chemical blowing process in the gas foaming technology and porogen leaching technology are combined, prepared the PLGA porous support.At first the chloroformic solution with PLGA precipitates in ethanol, with PLGA-ethanol gel and NH ₄HCO ₃Even and the mold of mix particles precipitates in aqueous citric acid solution then, and obtaining average pore size after the lyophilization is that 200 μ m, porosity surpass 90% porous support.

Yet, when using porogen leaching technology, all there is the residual toxigenous problem of porogen pair cell, for solving this difficult problem, trials such as Guoping Chen are studied as porogen with ice pellets.Guoping Chen etc. ^[34,35]Obtain ice pellets by spray deionized water in liquid nitrogen, then ice pellets is dispersed in the chloroformic solution of PLLA or PLGA, obtaining average pore size after the lyophilization is that 237 μ m, porosity are 95% porous support.

2002, Li Wanjun etc. ^[36]Utilize electrospinning silk technology (electrospinning) to prepare the PLGA nano fiber scaffold.The fibre diameter of support is 500～800nm, porosity height, mechanical performance is suitable and the form of extracellular matrix is similar.

Xinhua Zong etc. ^[37]Studied of the influence of electrospinning silk technology, and proved that this support can be used for carrying medicament amorphous PDLLA support and hypocrystalline PLLA support nanostructured form.PDLLA and PLLA are dissolved in N respectively, in dinethylformamide (DMF) and dichloromethane-DMF mixture, add the salt porogen, and add antibiotics Mefoxin and weak ionic compound, then polymer solution is injected electrostatic spinning device, spinning under certain condition.By regulator solution viscosity (solution concentration and polymer molecular weight), electric field intensity, the injection rate of solution and the content of ion salt, can regulate the diameter of fiber and the form of nanostructured.Support surpasses 90% for the load factor of antibiotic medicine.

2003, Cathryn Sundback etc. ^[38]In conjunction with mold and thermal induction phase detachment technique, prepared the polymer support of special construction form.With D, L-PLGA is dissolved in the glacial acetic acid under the room temperature, and solution is injected the special dies that is cooled to-40 ℃, and solution generation solid-liquid is separated, and obtains the pipe-like porous support with the peripheral nerve similar after the cold drying.The structure of tubular bracket can be a pipeline that diameter is 1.35mm, also can be 100 pipelines that diameter is 0.08mm.

Luo Binghong ^[39]Solution-cast/particle leaching technology is improved, developed a kind of new porous support manufacture method---low grade fever high pressure technique.With PLGA75/25 in liquid nitrogen freezing after, pulverize through high speed disintegrator, sieve is got the granule that particle diameter is 200～250 μ m, with the granular NaCl of same particle size range by certain mass than mixing.With the compression molding under 75 ℃, 6.5MPa condition of the mixture that stirs, immerse cyclic washing in the distilled water then, treat to remove fully drying under reduced pressure behind the NaCl, obtain porous PLGA support.The support hole wall of the method preparation is extremely thin, hole connective fine, and hole is evenly distributed, and the aperture is between 200～250 μ m, and porosity is more than 90%.This method need not with an organic solvent, helps the supported active factor in support.With ethanol and calcium alginate support is handled and obviously to be improved its hydrophilic and biomechanical property.

Qingpu Hou etc. ^[40]In conjunction with solidify, mold pressing and salt leaching technology prepared porous polymer scaffold.Add a certain amount of garbled salt particle at certain density PDLLA-chloroformic solution, stirring is dispersed in the solution salt particle fast, is poured into then in the ethanol, and polymer-salt is precipitated out.After the drying, the mixture that is settled out is cut into definite shape, and compression molding under 120 ℃, 3.5MPa, then fast cooling to 15 ℃.Polymer-salt after the molding is put into deionized water leach salt, can obtain porous support behind the vacuum drying, the aperture is at 250～425 mu m ranges, and porosity is 95.7%.Compare with traditional pore method (as sintering microsphere, mold pressing-salt leaching, lyophilization), this method can better be controlled the aperture and the porosity of support, and the form in hole is homogeneous more.

In order further to control the internal structure of porous support, Chen Jida ^[41]Prepared the spherical porogen of new type water-solubility by solution dispersion and centrifugal bonding technology.With the PDLLA porous support of this porogen preparation, the aperture is at 220～600 mu m ranges, and porosity is in 83%～95% scope, be interconnected between the hole and communication passage for circular, channel diameter can be by the bonding extent control.The preparation method of this porogen is: methyl-silicone oil is heated to 240～250 ℃, after gradation adds a certain amount of sodium chlorate, continues to be warming up to 270 ℃, this moment the sodium chlorate microsphere that in methyl-silicone oil, is in a liquid state; The cooling methyl-silicone oil makes the liquid microsphere of sodium chlorate be solidified into solid-state-microspherical rapidly rapidly; Remove methyl-silicone oil and can obtain spherical porogen.With chloroform and ether washing porogen microsphere, dry then successively.Spherical porogen is put into from molding jig, bonding under certain condition, centrifugal 5min under the 1000r/min condition repeats repeatedly to bond, centrifugal process, makes porogen microsphere intensive drying, can obtain porogen microsphere coherent mass.

R.M.Luciano etc. ^[42]In the process of preparation PLLA film, add plasticizer, obtained the loose structure of suitable cell growth.PLLA is dissolved in dichloromethane and adds a certain amount of triethyl citrate, then with solution casting on glass plate, dry removing desolvated under room temperature.Film is become by the big set of balls of diameter at 60～100 mu m ranges, on the big ball mutual successive hole is arranged.Plasticizer can strengthen the adsorptivity and the energy for growth of cell, but film is become fragile.

Angela S.P.Lin etc. ^[43]Utilize the method that solution applies and porogen decomposes (solution coating and porogendecomposition), preparation has the poly-(L-lactide-co-D of the micropore of the macropore of axial orientation and random distribution, the L-lactide, 70: 30) (PLDL) support.With azodicarboamide (C ₂H ₄N ₄O ₂) and the PLDL granule mix by a certain percentage and be dissolved in the anhydrous propanone, solution is coated in the 316 stainless steel silk surfaces of 100 μ m, coated weight is about 75mgPLDL-azodicarboamide/m stainless steel silk.Stainless steel silk after the coating of 55～65 long 100mm is put into collapsible tube, it is merged, immerse after the demoulding that 20～30s decomposes foaming agent in 260 ℃ the Oleum Arachidis hypogaeae semen in 125 ℃ of heating 25min.Sample after the foaming is put into quenching-in water immediately, go out Oleum Arachidis hypogaeae semen, extract stainless steel silk out and can obtain porous support with hexane extraction.Greater than 99%, porosity can reach 80% with the connection rate of the bracket holes of this method preparation.

Jong Hoon Lee etc. ^[44]The preparation PLLA porous support that also salt leaching technology and chemical blowing process combined, and characterized the hot property and the mechanical performance of support.They add graininess NH in the PLLA-chloroformic solution ₄HCO ₃/ NaCl (particle diameter is at 150～300 mu m ranges) mixture and 2M2HT-MMT clay.Polymer/salt/solvent mixture is poured on the homemade sheet glass mould constant pressure and dry.Behind the mixture semi-solid preparation, in the water with 90 ℃ of its immersions, NH ₄HCO ₃Decompose and generate ammonia and CO ₂, after waiting to no longer include bubble and producing, mixture immersed in 60 ℃ the water, leach residual NaCl, then lyophilization.The porosity of gained support is 91～92%, and the hole height is communicated with, and the aperture is at 100～300 mu m ranges.In the PLLA support, add clay, degree of crystallinity reduction, the stretch modulus of support are increased, so that obtain hardness and all suitable support of degradation speed.

2004, Li Shirong etc. ^[45]Phase separation by PLLA/ dioxane (DO)/oxolane (THF) ternary system is proposed, preparation PLLA porous foam.With PLLA be dissolved in the different DO/THF mixture of a certain amount of composition (50/50,70/30,90/10, v/v) in, and at 50 ℃ of constant temperature 1h, immerse then in dry ice/crude alcohol mixture of-70 ℃ and quench.The gel that obtains is immersed in distilled water and the ethanol successively, extract solvent ,-10 ℃ of lyophilizations, can obtain porous support then.In ternary system, DO is as good solvent, and THF is as poor solvent, and the ratio of DO and THF has determined the solvability of solvent.The form of gained support and degree of crystallinity depend on the solvability of solvent, and when the content of DO was 70%, aperture minimum of support (at 1～3 mu m range) and relative crystallinity were minimum; When the content of DO was 50% or 90%, average pore size was bigger, at 3～10 mu m ranges.Select for use THF as poor solvent, be because and the water ratio, it can drop to minimum with the probability of PLLA hydrolysis, and removes at low temperatures easilier.

Pierre Sarazin etc. ^[46]Utilize fusion technology, prepare the PLLA porous support by the common continuous mixture of two kinds of biodegradable polymers.Dried PLLA and polycaprolactone (PCL) are mixed under 200 ℃, put into liquid nitrogen behind the 5min and quench to keep its form, the PLLA/PCL mixture that difference is formed is annealed with different speed at 200 ℃ then.Extract PCL with acetic acid, then with sample drying to constant weight, can obtain the successive PLLA support of hole height.By the concentration and the annealing time of two components (PLLA and PCL) in the control mixture, can obtain the porous support of different shape, average pore size is at 1.5～88 mu m ranges, and porosity is in 50%～60% scope.They utilize similar approach again subsequently, have prepared the PLLA porous support by PLLA-polystyrene (PS) system.They obtain certain form degree PLLA/PS mixture with PS, PLLA and PS-co-PLLA (containing 45wt%PS) mixture fusion through steps such as quenching, annealing.Extract PS with cyclohexylamine and can obtain PLLA macropore support.Can obtain pore diameter range in 1 network structure by the control annealing conditions to the hundreds of micron ^[47]

V.Maquet etc. ^[48,49]Prepared poly-(Alpha-hydroxy the acetic acid)/bio-vitric porous foam that is used for bone tissue engineer by the thermal induction phase detachment technique.In the DMC dimethyl carbonate solution of PDLLA or PLGA (75: 25), add a certain amount of bio-vitric powder (Bioglass

), mixture is cast on the culture dish, freezing its generation solid-liquid that makes is separated in liquid nitrogen, and vacuum drying is to constant weight then.A pipe is put in dried perforated membrane rotation, slowly dissolved its edge with chloroform and also relative both sides are sticked together, can obtain the tubulose porous foam.The volume of the concentration by changing polymer and the polymer solution of casting, the internal diameter that can adjustable pipe and the thickness of tube wall are in 1.5～3mm scope.Foamy hole radially distributes, and the seriality in hole is good, and the hole in two kinds of different apertures is arranged---and average pore size is at the macropore of 100 μ m and the average pore size micropore at 10～50 μ m.Add bio-vitric and can increase foamy biological activity, and can change foamy degradation rate.

Hyun Do Kim etc. ^[50]Utilize the thermal induction phase detachment technique to prepare the PLLA porous support, and studied the influence of additive PEG (Polyethylene Glycol)-PLLA support character.PLLA is dissolved in dioxane/aqueous mixtures (87: 13, w/w), add PEG or PEG-PLLA bipolymer, obtain the PLLA support through steps such as ageing, quenching, lyophilizations.Add PEG-PLLA and can prevent that segregation and deposited phenomenon take place polymer solution in long ageing process, the hole gauge that obtains is whole and highly continuous, and the aperture is easy to be controlled at 50～300 μ m.The PLLA support that has added PEG-PLLA is used to cultivate the MC3T3-E1 cell, and four stars after date cell is successfully bred.

Takaaki Tanaka and Douglas R.Lloyd ^[51]Also utilize the thermal induction phase detachment technique to prepare the PLLA micro-filtration membrane.Use G﹠amp; The device that S metallic article company produces prepares the PLLA perforated membrane, and this device is made up of three stainless steel discs.(87/13, wt) solution is placed more than the 30min in 80 ℃ airtight bottle, then solution is poured in the bottom disk and is placed 5min in 80 ℃ with dioxane one water of PLLA.The 3rd disk is placed on topmost, then solution placed 10min at 80 ℃.The upper strata disk can stop the conduction of heat between intermediate disc and the air.5min is cooled off in the water-bath that device is put into 50 ℃, puts into 0 ℃ the ice-water bath 1h that quenches then, and solution will form gel like this, with cooling water detergent gel three times, can obtain perforated membrane.The effective aperture of film is between yeast cells (ellipse, minor axis length are 4.4 μ m) and E Bacillus coli cells (clavate, diameter are 0.6 μ m).

Lakhwant Singh etc. ^[52]With supercritical CO ₂Be foaming agent, utilize the gas foaming technology to prepare the PLGA porous foam, and studied process condition CO ₂The absorption rate in PLGA and the influence of equilibrium concentration.Dried PLGA bead is pressed into lamellar, puts into bomb, under uniform temperature (35 ℃ or 40 ℃), certain pressure (10,14,15 or 20MPa) sample is reached capacity, decompression discharges CO ₂Can obtain porous foam.Significantly mutual successive hole is arranged in the foam, and porosity is 89%, and the aperture is at 30～100 mu m ranges.

Calendar year 2001 Peter X.Ma etc. continues ^[29]Develop after the paraffin ball porogen, they had prepared the PLLA three-dimensional rack with this porogen again in 2004, and the aperture of support is at 250～500 mu m ranges, and porosity is up to 99% ^[30]

M.Navarro etc. ^[53]Calcium phosphate glass and PLA are mixed, prepared the PLA porous support by porogen leaching technology.The support that obtains has mutual successive pore structure, and porosity is up to 97%.The interpolation calcium phosphate glass can significantly improve the resistance to pressure and the biological susceptiveness of support.

At P.van de Witte in 1996 ^[11,12]Deng utilizing non-solvent to induce phase detachment technique to prepare on the basis of PLA perforated membrane technology, 2004 years Hwa-Chang Liu etc. ^[54]Utilize non-solvent to induce phase detachment technique to prepare the PLLA perforated membrane of different shape again, they are used to cultivate the MG-63 cell with these films, find not only can promote osteoblastic absorption and growth, can also promote osteoblastic phenotype.

Takashi Sato etc. ^[55]With PLLA and the ossein mixing porous material that has been feedstock production.At first utilize porogen leaching technology to prepare the PLLA porous material, under vacuum condition, it is immersed then cattle I type ossein acid solution (0.5%, pH3.2) in ,-80 ℃ freezing, can form the PLLA-ossein after the lyophilization and mix porous support.Compare with the PLLA support, cartilaginous tissue is easier to grow on PLLA-ossein support, and is more evenly distributed.With PLLA support and the combination of ossein support, can promote cell implantation, prevent that support from subsiding and can promote cartilaginous tissue molding in vivo.

Haiyan Li etc. ^[56]Utilize solution-cast/salt leaching technology to prepare the wollastonite/polylactic acid compound rest of biologically active.In the chloroformic solution of PDLLA, add wollastonite and granular NaCl,, obtain spongy support through steps such as solution-cast, salt leaching, vacuum dryings.Support has mutual successive macroporous structure, the aperture from tens microns to the hundreds of micron, porosity reaches as high as 95%.Support is immersed in the simulated body fluid, generate one deck hydroxyapatite at rack surface after 7 days; The acidity that Ca that compound rest discharges and Si ion can limit the PDLLA degradation by-products can keep the acidity of simulated body fluid between 6.7～7.2 in 3 week; In addition, the wollastonite in the compound rest can strengthen the hydrophilic of support.

Richard M.Day etc. ^[57]Utilize the thermal induction phase detachment technique to prepare tubulose PLGA foamed materials and used as tissue engineering bracket material.PLGA75 be dissolved in the DMC dimethyl carbonate form certain density solution, by thermal induction be separated, step such as lyophilization, obtain polymer porous film.Film is rolled into tubulose, and edge slowly dissolves with chloroform and forces together, and obtains long 20mm, and internal diameter is about 3mm, and pipe thickness is about the tubulose foamed materials of 1.5mm.Hole in the foam mutually continuously and radially distribute, pore-size distribution broad (50～300 μ m), porosity is greater than 93%.This support is implanted in the public Mus body of growing up, shown excellent biological compatibility.

The same year, F.Yang etc. ^[58,59]The PLLA nano fiber scaffold that has prepared directed and random orientation again with electrostatic spinning technique respectively, and two kinds of supports are respectively applied for nervous tissue's engineering.PLLA is dissolved in dichloromethane/N, forms certain density solution in the dinethylformamide (DMF) (70: 30), polymer solution is injected instrument with the speed of 1.0mL/h, select the pin that spins of different inner diameters at the solution of variable concentrations.Rotating speed at rotating disk is to spray polymer solution under 1000rpm, the 12kV unidirectional current condition, collects the PLLA fiber on catcher.Collect fiber with rotating disk, and collect the fiber of random orientation with flat aluminium sheet with certain orientation.For directed support, fiber diameter is 300nm to 1.5 μ m; For the support of random orientation, fibre diameter is 700nm to 3.5 μ m.From the result of cell culture experiments as can be seen, in directed support, neural stem cell and neurite are along the direction growth of fiber; When the fibre diameter of support is nanoscale, be easier to the differentiation of neural stem cell and the growth of neurite, and can also promote the adhesion of neural stem cell.

2005, Kyu Chul Shin etc. ^[60]Mixture with PLGA/PLLA is a raw material, utilizes the liquid-liquid phase separation method in the thermal induction phase detachment technique to prepare the macroporous polymer support.The PLGA/PLLA mixture is dissolved in dioxane/water (87/13, wt/wt) in, and add a certain amount of Polyethylene Glycol (PEG) or PEG-PLLA dimer, by steps such as ageing, annealing, lyophilizations, obtain the whole and mutual successive macropore support of hole gauge, the aperture of support is at 50～200 mu m ranges.Adding PLLA can increase the viscosity of PLGA/PLLA solution, and the mechanical strength of porous support is increased, and the cloud point temperature that can raise, and thermodynamic driving force is increased.Add ampholyte copolymer PEG and can reduce interfacial tension, obtain the macropore support that the hole seriality is good and mechanical strength is high.

Anita W.T.Shum etc. ^[61]With dispersive paraffin ball is porogen, utilizes porogen leaching technology to prepare the PLGA porous support.Adopt the way that while stirring fused paraffin is added in the PVA aqueous solution, mixture is poured into obtained the paraffin ball in the cold water then, also obtain the PVA precipitation simultaneously.Remove most of PVA precipitation and large-sized paraffin ball with sieve, wash PVA residual in the deparaffnize ball then with water, rescreen out the paraffin ball of particle diameter, with second distillation water washing three to five times less than 100 μ m.The paraffin ball is put into the paraffin foam that home-made contrivance forms definite shape, extrude excessive water,, at 37 ℃ of heating 30min, be cooled to room temperature then again 30 ℃ of 1 weeks of drying.The pyridine solution of PLGA50/50 is added drop-wise to makes it be full of hole between the paraffin ball on the paraffin foam, elder generation places paraffin foam and polymer solution the environment of vacuum lower (60mmHg), air in the scumming, placing vacuum again, higher (environment of pressure＜0.5mmHg) removes and desolvates.In room temperature paraffin/polymer samples is soaked 2 days except that deparaffnize in normal hexane, in cyclohexylamine, soak again and remove normal hexane.With sample-20 ℃ down behind the freezing 6h in-10 ℃ of following lyophilizations two days, one week of vacuum drying at room temperature again.Obtained the porous support materials of four kinds of different apertures (150～180 μ m, 180～250 μ m, 250～280 μ m, 280～400 μ m) with said method, porosity all reaches 90%.

Min Lee etc. ^[62]Utilize indirect 3 D-printing technology (indirect three-dimensional printing) preparation to have the PLGA porous support of given shape.Promptly earlier make gypsum mold by the 3 D-printing technology, the PLGA solution that will be mixed with porogen then injects mould, and lyophilization removes and desolvates.Leach mould and porogen with distilled water, promptly get required porous support after the drying.This support has pore structure open, that seriality is good.The PLGA support that makes is used for the In vitro culture of enterocyte (IEC6), cell evenly absorption and well-grown on support.Directly the 3 D-printing technology has certain limitation to the structure of support, and the aperture of gained support is usually less than 150 μ m, and the optimum aperture of osteogenesis is 200～400 μ m; And using direct 3 D-printing technology, the organic solvent in the polymer solution also can dissolve the shower nozzle of printer usually.The advantage of this indirect 3 D-printing technology is to prepare complex-shaped porous support, also can solve the deficiency in the direct printing technique.

Xinhua Zong etc. ^[63]After utilizing electrostatic spinning technique to prepare PDLLA and PLLA support ^[36], prepared non-woven fibre with this method again, and used it for heart tissue engineering based on PLGA.The fiber diameter of gained support is 0.9～1.0 μ m, and porosity reaches as high as 78%.Before carrying out cell culture experiments, static spinning membrane is carried out uniaxial tension, can obtain anisotropic fibre structure.This non-woven fibre support can guide the growth of myocardial cell, and can obtain the suitable myocardial tissue structure of 26S Proteasome Structure and Function.

2006, You Young etc. ^[64]Studied the influence of SOLUTION PROPERTIES to PLGA electrostatic spinning nano fibre structure.PLGA is dissolved in chloroform or 1,1,1,3,3, and in 3-hexafluoro-2-propanol (HFIP), forming concentration is the solution of 15wt%, obtains the support of fiber diameter in 270～760nm scope by electrostatic spinning technique.Add a small amount of benzyltriethylammoinium chloride (BTEAC) in the PLGA/ chloroformic solution, fiber diameter drops to 450nm from 760nm; Use the nanofiber fiber diameter of polar solvent HFIP preparation to be 270nm, more much smaller than the average fibre diameter (760nm) that with chloroform is the solvent preparation.

Ho Joon Shin etc. ^[65]PLGA (75/25 with the difference composition, 50/50,75/25 and 50/50 mixture) be raw material, prepare the PLGA nano fiber scaffold by electrostatic spinning technique, and studied the mechanical performance, degradation speed of support and under mechanical stimulus cell to the reaction of support.The mechanical stability of this nano fiber scaffold is better, can not subside after implanting, and can support the regeneration of cartilaginous tissue.

Shanta Raj Bhattarai etc. ^[66]Utilize electrostatic spinning technique to prepare hydrophilic PLLA nanofiber nonwoven fabric, and studied the interaction of propagation, form and the intercellular substance of fibroblast NIH3T3 on this non-woven fibre.Adding Polyethylene Glycol (PEG) can increase the hydrophilic of PLLA fiber, when PLLA/PEG=80/20, meet most the biological activity requirement of NIH3T3 fibroblast, fibre diameter is at 540～850 mu m ranges at this moment, and the aperture in most of holes is less than 100 μ m, and hot strength is 8MPa, rate elongation is 150%, porosity is higher than 90%, and along with the generation of hydrolytic degradation process, the hydrophilic of fiber increases gradually.

Xiaoxi Wang etc. ^[67]Bound gas foaming and ultrasonic technology are inquired into the method for preparing tissue engineered porous scaffold.They are at first by the gas foaming technology ^[52]Obtained the PLLA porous foam, then according to the relative density of ASTM canonical measure sample, selected the sample of relative density minimum (9%) to use ultrasonic Treatment 60s at 21 ℃, frequency of ultrasonic is 20kHz, and peak power is 750W.Result of study shows, use the ultrasonic Treatment sample, can significantly increase the connectedness between the lipostomous in the support, but not remarkable to the change in aperture---the aperture of handling preceding lipostomous is at 30～70 μ m, and the aperture of handling mutual successive hole, back is at 30～90 μ m.

I.Tsivintzelis etc. ^[68]Adopt CO ₂For the way of anti-solvent has prepared the PLLA porous support.Certain density PLLA-dichloromethane solution is put into home-made contrivance, at the supercritical CO of uniform temperature, certain pressure ₂The middle 2.5h that soaks constantly charges into fresh CO then under uniform temp and pressure ₂, so that extract organic solvent, behind the 2.5h with slowly blood pressure lowering of constant rate of speed (1bar/min).Because PLLA is a semi-crystalline polymer, can not utilize the gas foaming technology to obtain the PLLA loose structure, yet, with CO ₂For anti-solvent then can address this problem.By adjusting temperature, initial concentration and pressure, can change the structure of porous support at an easy rate.

Taek Kyoung Kim etc. ^[69]With improved water-oil-water (W ₁/ O/W ₂) two emulsion solvent evaporation techniques have prepared PLGA microsphere, W ₁In dissolved salia effervescentia (NH ₄HCO ₃) can spontaneous generation CO in the solvent evaporates process ₂And NH ₃, not only can make emulsion more stable, can also in the microsphere that obtains, produce successive hole.Concrete grammar is as follows: a certain amount of PLGA is dissolved in the dichloromethane, adds certain density NH again ₄HCO ₃Aqueous solution, kind of the water/fat liquor of promptly winning after stirring.This emulsion is poured into rapidly in the aqueous solution of PVA that concentration is 0.1% (w/v), promptly got two emulsions after stirring.After solvent evaporation is intact, separate microsphere with centrifuging, use distilled water wash then, carry out lyophilization at last.The PLGA diameter of micro ball is at 343～535 mu m ranges, and the average pore size in lip-deep hole is 20 μ m.As the microcarrier of cultivating the NIH3T3 cell, cell adsorbed on microsphere surface equably in the 1st day with this porous microsphere, and cell is successfully in the inner propagation of microsphere after 7 days.

Se Heang Oh etc. ^[70]Utilize fusion mold one particle leaching technology to prepare hydrophobic PLGA porous support and hydrophilic PLGA/ polyvinyl alcohol (PVA) porous support.PLGA and PVA is freezing and grind and granulate in liquid nitrogen, with granular PLGA and PVA (0 or 5wt%) mix homogeneously, depress to flaky mixture in 30MPa, 80 ℃ of conditions.Lamellar PLGA/PVA mixture is put into mould, and on the mixture upper and lower surface all covers a certain amount of salt particle (particle diameter is at 200～300 μ m).Mould at 20～30MPa, 180 ℃ of following mold pressing 1min, at 50～60MPa, 180 ℃ of following mold pressing 30s, after the demoulding is immersed mixture and leaches the salt grain in the water, carry out lyophilization at last.The gained rack surface is consistent with inner porosity, all reaches 90%, and the aperture is 200～300 μ m, is open pore structure.This method does not need with an organic solvent, and being evenly distributed of the support mesopore that makes.Show surrounding and degradation behavior external, that the interior condition of body all can influence the PLGA support in the body with the external degradation experimental result; Add the hydrophilic that a small amount of PVA (5wt%) can change the PLGA/PVA support, can accelerate the degradation speed of PLGA support thus.

Junchuan Zhang etc. ^[71]Room temperature mould pressing technology and wax ball hole forming technology are combined, prepared three-dimensional PLGA support with spherical macropore.Add 20g paraffin and 1g gel in the 400mL deionized water, 80 ℃ of stirrings make its mix homogeneously.Under stirring, in mixture, add the 300mL frozen water behind the 2h, fused paraffin is solidified, filter and obtain the wax ball, with deionized water wash several final vacuum drying.1g PLGA85 is dissolved in the 5mL acetone, in polymer solution, adds the wax ball and make it form the semisolid mixture.Mixture is pressed in the mould, under certain pressure, keeps 4h, then the demoulding and in vacuum tank, place 48h and remove residual solvent.After treating that solvent evaporates is intact, go out the wax ball with n-hexane extraction, vacuum drying at room temperature can obtain porous support again.The porosity of support is up to 97%; When the porosity of support was 90%, modulus of compressibility surpassed 3MPa, and compressive strength surpasses 0.2MPa.This support is used to cultivate the 3T3 fibroblast, the support no cytotoxicity.

Xiaohua Liu, Peter X.Ma etc. ^[72]Be again porogen with the gel ball,, obtained the PLLA nano fiber scaffold of surface modification carrying out when thermal induction is separated gel ball being embedded fiber surface.The method for preparing gel ball is: gel-aqueous solutions of 45 ℃ are joined in 45 ℃ the mineral oil, cool off rapidly after stirring 10min fast, after the temperature of mixture is reduced to below 0 ℃, add the ethanol that is cooled to-18 ℃, can see in the bottom of mixture having gel ball to precipitate after stopping to stir.Remove mineral oil for several times with the washing with acetone gel ball, leach gel ball, the reuse dioxane carries out solvent exchange, lyophilization then.The gel ball that obtains is filtered with standard screen, can obtain testing required gel ball.The preparation method of nanofiber PLLA support is that mould is put at the gel ball of 250～425 mu m ranges in the cut-off footpath, keeps the upper surface level, with steam heating a period of time of 37 ℃.PLLA-water-tetrahydrofuran solution is dropwise joined through in the gel pelletizing of preheating, be cooled to-76 ℃ then rapidly, solution is separated and makes in the solution of gel embedding phase-splitting.Extract the solvent in gel/polymer and carry out lyophilization with cyclohexylamine, the reuse distilled water leaches gel and carries out lyophilization, can obtain the PLLA nano fiber scaffold.Compare with the support of the irregular preparing gel of using the same particle size scope, use the support modulus of compressibility of gel ball preparation to want Senior Three doubly.This support through surface modification also can promote the absorption and the propagation of cell.

The above-mentioned method for preparing porous support materials all exists weak point, connective bad, the freeze-drying that prepare the porous material porous material that salt residue, gas foaming method obtain in porous material easily as porogen leaching technology expend a large amount of energy, simultaneously in freezing dry process, because drying time is long, the material easy deformation.Some can obtain porous material by the way with the freezing quenching of polymer solution, room temperature solvent exchange, but limitation is very big, because polymer can gel during low temperature in the organic solvent of these uses, cause porous material to subside or be out of shape and when room temperature, can dissolve or be partly dissolved.The other way of introducing in the above-mentioned document can only prepare porous membrane or the pore size of prepared porous material can not be controlled.

Summary of the invention

The preparation method that the purpose of this invention is to provide a kind of porous support materials of micropore bicontinuous structure, the porous support materials hole connectivity of this method preparation is good, the size in hole compares homogeneous, and the size in this method hole can be controlled, be fit to preparation large scale cell growth support or guide tissue regeneration material.

To achieve these goals, technical scheme of the present invention is: the preparation method of the porous support materials of micropore bicontinuous structure, it is characterized in that it comprises the steps: earlier polymer to be put into organic solvent N, dinethylformamide or N, heating for dissolving in the mixed solvent of dinethylformamide and oxolane, obtain polymer solution, the concentration of polymer in organic solvent is 0.01-0.2g/mL, and described polymer is poly--L-lactic acid (PLLA) or polyglycolic acid (PGA) or polycaprolactone (PCL) or their the copolymer (copolymer of poly--L-lactic acid, the copolymer of polyglycolic acid, the copolymer of polycaprolactone); Then with polymer solution 0 ℃ of-95 ℃ of constant temperature ageing, digestion time is 0.5-2h; Be freezing quenching under-200 ℃-0 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 5min-4h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-100 ℃-0 ℃ the low temperature with the alcohol extraction of extractant dehydrated alcohol or 95% up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Described organic solvent is N, during the mixed solvent of dinethylformamide and oxolane, and N, the volume ratio of dinethylformamide and oxolane is: 0.5: 9.5-9.5: 0.5.

The present invention adopts the method that exchange combines with low-temperature solvent that is separated in the porous support materials preparation process, because phase separation method does not need special equipment, the condition that is separated by control, can control the pattern in the pore size of resulting polymers porous material and pore-size distribution thereof, hole, and employing low-temperature solvent exchange process, promptly carry out solvent exchange, before drying, from polymer-dicyandiamide solution, extract solvent in lower temperature; Afterwards, polymer is surrounded by non-solvent, and the dissolving again of polymer can not take place dry run.Therefore the porous support materials hole connectivity of the present invention's preparation size good, the hole compares homogeneous.The present invention both can conveniently prepare the porous support materials or the guide tissue regeneration material of large scale, even structure, the size in this method hole can be controlled, can select for use different solvents and process conditions to prepare porous support materials according to requirement again to porous support materials pore size, mechanical strength etc.

Description of drawings

Fig. 1 is the scanning electron microscope image of the porous support of embodiments of the invention 1

Fig. 2 is the scanning electron microscope image of the porous support of embodiments of the invention 2

Fig. 3 is the scanning electron microscope image of the porous support of embodiments of the invention 3

Fig. 4 is the scanning electron microscope image of the porous support of embodiments of the invention 4

Fig. 5 is the scanning electron microscope image of the porous support of embodiments of the invention 5

Fig. 6 is the scanning electron microscope image of the porous support of embodiments of the invention 6

The specific embodiment

In order to understand the present invention better, further illustrate content of the present invention below in conjunction with embodiment, but content of the present invention not only is confined to the following examples.

Embodiment 1:

Get 0.8g poly--L-lactic acid joins in the single port flask of taking back the stream device, adds the N of 10mL then, the dinethylformamide solvent, the little backflow of heating is dissolved poly--L-lactic acid fully under magnetic agitation, preparation concentration is poly--L-lactic acid solution of 0.08g/mL.Then gained solution is transferred in the mould, kept 0.5h (constant temperature ageing) at 50 ℃.The mould that will contain poly--L-lactic acid solution is again transferred to rapidly in-30 ℃ of temperature baths and is quenched, and keeps 2h in hardening heat.In this process, solution becomes gel.The temperature bath of then this gel demoulding being put into-30 ℃ carries out solvent exchange 4h with-30 ℃, 95% ethanol, the temperature bath of putting into 0 ℃ then rapidly carries out solvent exchange with 0 ℃, 95% ethanol, up to using gas chromatographic detection less than N, till the dinethylformamide.Gained sample at room temperature vacuum drying gets product (porous support materials of micropore bicontinuous structure) to constant weight.The scanning electron microscope image of the porous support that present embodiment 1 obtains as shown in Figure 1, this porous support materials hole connectivity is good, the size in hole homogeneous relatively; Average pore size is 0.23 μ m.

Embodiment 2:

Get 0.7g poly--L-lactic acid joins in the single port flask of taking back the stream device, adds the N of 10mL then, the dinethylformamide solvent, the little backflow of heating is dissolved poly--L-lactic acid fully under magnetic agitation, preparation concentration is poly--L-lactic acid solution of 0.07g/mL.Then gained solution is transferred in the mould, kept 0.5h (constant temperature ageing) at 50 ℃.The mould that will contain poly--L-lactic acid solution is again transferred to rapidly in-30 ℃ of temperature baths and is quenched, and keeps 2h in hardening heat.In this process, solution becomes gel.The temperature bath of then this gel demoulding being put into-30 ℃ carries out solvent exchange 4h with-30 ℃, 95% ethanol, the temperature bath of putting into 0 ℃ then rapidly carries out solvent exchange with 0 ℃, 95% ethanol, up to using gas chromatographic detection less than N, till the dinethylformamide.Gained sample at room temperature vacuum drying gets product (porous support materials of micropore bicontinuous structure) to constant weight.The scanning electron microscope image of the porous support that present embodiment 2 obtains as shown in Figure 2, this porous support materials hole connectivity is good, the size in hole homogeneous relatively; Average pore size is 0.25 μ m.

Embodiment 3:

Get 0.3g poly--L-lactic acid joins in the single port flask of taking back the stream device, the N that adds 10mL then, dinethylformamide, oxolane mixed solvent, N, the volume ratio of dinethylformamide and oxolane is 1: 9, the little backflow of heating is dissolved poly--L-lactic acid fully under magnetic agitation, and preparation concentration is poly--L-lactic acid solution of 0.03g/mL.Then gained solution is transferred in the mould, kept 0.5h (constant temperature ageing) at 50 ℃.The mould that will contain poly--L-lactic acid solution is again transferred to rapidly in-30 ℃ of temperature baths and is quenched, and keeps 2h in hardening heat.In this process, solution becomes gel.The temperature bath of then this gel demoulding being put into-30 ℃ carries out solvent exchange 4h with-30 ℃, 95% ethanol, the temperature bath of putting into 0 ℃ then rapidly carries out solvent exchange with 0 ℃, 95% ethanol, up to using gas chromatographic detection less than N, till dinethylformamide and the oxolane.Gained sample at room temperature vacuum drying gets product (porous support materials of micropore bicontinuous structure) to constant weight.The scanning electron microscope image of the porous support that present embodiment 3 obtains as shown in Figure 3, this porous support materials hole connectivity is good, the size in hole homogeneous relatively; Average pore size is 0.25 μ m.

Embodiment 4:

Get 0.4g poly--L-lactic acid joins in the single port flask of taking back the stream device, the N that adds 10mL then, dinethylformamide, oxolane mixed solvent, N, the volume ratio of N-methylformamide and oxolane is 1: 9, the little backflow of heating is dissolved poly--L-lactic acid fully under magnetic agitation, and preparation concentration is poly--L-lactic acid solution of 0.04g/mL.Then gained solution is transferred in the mould, kept 0.5h (constant temperature ageing) at 50 ℃.The mould that will contain poly--L-lactic acid solution is again transferred to rapidly in-30 ℃ of temperature baths and is quenched, and keeps 2h in hardening heat.In this process, solution becomes gel.The temperature bath of then this gel demoulding being put into-30 ℃ carries out solvent exchange 4h with-30 ℃, 95% ethanol, the temperature bath of putting into 0 ℃ then rapidly carries out solvent exchange with 0 ℃, 95% ethanol, up to using gas chromatographic detection less than N, till dinethylformamide and the oxolane.Gained sample at room temperature vacuum drying gets product (porous support materials of micropore bicontinuous structure) to constant weight.The scanning electron microscope image of the porous support that present embodiment 4 obtains as shown in Figure 4, this porous support materials hole connectivity is good, the size in hole homogeneous relatively; Average pore size is 0.25 μ m.

Embodiment 5:

Get 0.7g poly--L-lactic acid joins in the single port flask of taking back the stream device, the N that adds 10mL then, dinethylformamide, oxolane mixed solvent, N, the volume ratio of dinethylformamide and oxolane is 2: 8, the little backflow of heating is dissolved poly--L-lactic acid fully under magnetic agitation, and preparation concentration is poly--L-lactic acid solution of 0.07g/mL.Then gained solution is transferred in the mould, kept 0.5h (constant temperature ageing) at 50 ℃.The mould that will contain poly--L-lactic acid solution is again transferred to rapidly in-30 ℃ of temperature baths and is quenched, and keeps 2h in hardening heat.In this process, solution becomes gel.The temperature bath of then this gel demoulding being put into-30 ℃ carries out solvent exchange 4h with-30 ℃, 95% ethanol, the temperature bath of putting into 0 ℃ then rapidly carries out solvent exchange with 0 ℃, 95% ethanol, up to using gas chromatographic detection less than N, till dinethylformamide and the oxolane.Gained sample at room temperature vacuum drying gets product (porous support materials of micropore bicontinuous structure) to constant weight.The scanning electron microscope image of the porous support that present embodiment 5 obtains as shown in Figure 5, this porous support materials hole connectivity is good, the size in hole homogeneous relatively; Average pore size is 0.50 μ m.

Embodiment 6:

Get 0.7g poly--L-lactic acid joins in the single port flask of taking back the stream device, the N that adds 10mL then, dinethylformamide, oxolane mixed solvent, N, the volume ratio of dinethylformamide and oxolane is 3: 7, the little backflow of heating is dissolved poly--L-lactic acid fully under magnetic agitation, and preparation concentration is poly--L-lactic acid solution of 0.07g/mL.Then gained solution is transferred in the mould, kept 0.5h (constant temperature ageing) at 50 ℃.The mould that will contain poly--L-lactic acid solution is again transferred to rapidly in-30 ℃ of temperature baths and is quenched, and keeps 2h in hardening heat.In this process, solution becomes gel.The temperature bath of then this gel demoulding being put into-30 ℃ carries out solvent exchange 4h with-30 ℃, 95% ethanol, the temperature bath of putting into 0 ℃ then rapidly carries out solvent exchange with 0 ℃, 95% ethanol, up to using gas chromatographic detection less than N, till dinethylformamide and the oxolane.Gained sample at room temperature vacuum drying gets product (porous support materials of micropore bicontinuous structure) to constant weight.The scanning electron microscope image of the porous support that present embodiment 6 obtains as shown in Figure 6, this porous support materials hole connectivity is good, the size in hole homogeneous relatively; Average pore size is 0.26 μ m.

Embodiment 7

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, and heating for dissolving in the dinethylformamide obtains polymer solution, the concentration of polymer in organic solvent is 0.01g/mL, and described polymer is poly--L-lactic acid; Then with polymer solution 60 ℃ of constant temperature ageings, digestion time is 1h; Be freezing quenching under-200 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 5min, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-100 ℃ the low temperature with the extraction of extractant dehydrated alcohol up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 8:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, and heating for dissolving on the dinethylformamide obtains polymer solution, the concentration of polymer in organic solvent is 0.2g/mL, and described polymer is poly--L-lactic acid; Then with polymer solution 60 ℃ of constant temperature ageings, digestion time is 2h; Be freezing quenching under-10 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 4h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under 0 ℃ the low temperature with the extraction of extractant dehydrated alcohol up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 9:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, heating for dissolving in dinethylformamide and the oxolane mixed solvent, obtain polymer solution, the concentration of polymer in organic solvent is 0.01g/mL, described polymer is poly--L-lactic acid, N, and the volume ratio of N-methylformamide and oxolane is: 0.5: 9.5; Then with polymer solution 40 ℃ of constant temperature ageings, digestion time is 0.5h; Be freezing quenching under-200 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 5min, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-100 ℃ the low temperature with the extraction of extractant dehydrated alcohol up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 10:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, heating for dissolving in the mixed solvent of dinethylformamide and oxolane, obtain polymer solution, the concentration of polymer in organic solvent is 0.2g/mL, described polymer is poly--L-lactic acid, N, and the volume ratio of dinethylformamide and oxolane is: 1: 1; Then with polymer solution 40 ℃ of constant temperature ageings, digestion time is 0.5h; Be freezing quenching under 0 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 4h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under 0 ℃ the low temperature with the extraction of extractant dehydrated alcohol up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 11:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, heating for dissolving in the dinethylformamide, obtain polymer solution, the concentration of polymer in organic solvent is 0.08g/mL, and described polymer is a polyglycolic acid; Then with polymer solution 80 ℃ of constant temperature ageings, digestion time is 1.5h; Be freezing quenching under-100 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 1h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-100 ℃ the low temperature with the extraction of extractant dehydrated alcohol up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 12:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, and heating for dissolving in the dinethylformamide obtains polymer solution, the concentration of polymer in organic solvent is 0.04g/mL, and described polymer is a polycaprolactone; Then with polymer solution 35 ℃ of constant temperature ageings, digestion time is 1h; Be freezing quenching under-50 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 2h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-20 ℃ the low temperature with the extraction of extractant dehydrated alcohol up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 13:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, heating for dissolving in the dinethylformamide, obtain polymer solution, the concentration of polymer in organic solvent is 0.03g/mL, and described polymer is the copolymer (PLGA80) of poly--L-lactic acid; Then with polymer solution 20 ℃ of constant temperature ageings, digestion time is 0.5h; Be freezing quenching under-20 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 2h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under 0 ℃ the low temperature with the alcohol extraction of extractant 95% up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 14:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, heating for dissolving in the dinethylformamide, obtain polymer solution, the concentration of polymer in organic solvent is 0.1g/mL, and described polymer is polyglycolic acid (PGA); Then with polymer solution 30 ℃ of constant temperature ageings, digestion time is 1h; Be freezing quenching under-10 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 4h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under 0 ℃ the low temperature with the alcohol extraction of extractant 95% up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Embodiment 15:

The preparation method of the porous support materials of micropore bicontinuous structure, it comprises the steps: earlier polymer to be put into organic solvent N, heating for dissolving in dinethylformamide and the oxolane mixed solvent, obtain polymer solution, the concentration of polymer in organic solvent is 0.2g/mL, described polymer is the copolymer (PLLA-PCL) of polycaprolactone, N, and the volume ratio of N-methylformamide and oxolane is 1: 1; Then with polymer solution 35 ℃ of constant temperature ageings, digestion time is 2h; Be freezing quenching under-80 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 4h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-50 ℃ the low temperature with the alcohol extraction of extractant 95% up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product (porous support materials of micropore bicontinuous structure).

Claims

1. the preparation method of the porous support materials of micropore bicontinuous structure, it is characterized in that it comprises the steps: earlier polymer to be put into organic solvent N, dinethylformamide or N, heating for dissolving in the mixed solvent of dinethylformamide and oxolane, obtain polymer solution, the concentration of polymer in organic solvent is 0.01-0.2g/mL, and described polymer is poly--L-lactic acid or polyglycolic acid or polycaprolactone or their copolymer; Then with polymer solution 0 ℃ of-95 ℃ of constant temperature ageing, digestion time is 0.5-2h; Be freezing quenching under-200 ℃-0 ℃ the low temperature again with the polymer solution after the ageing, and remain on hardening heat 5min-4h, it is separated, produce gel in temperature; Then adopt the low-temperature solvent exchange process, with gel be in temperature under-100 ℃-0 ℃ the low temperature with the alcohol extraction of extractant dehydrated alcohol or 95% up to organic solvent by after the displacement fully substance A; At last with substance A at room temperature vacuum drying get product.

2. the preparation method of the porous support materials of micropore bicontinuous structure according to claim 1, it is characterized in that: described organic solvent is N, during the mixed solvent of dinethylformamide and oxolane, N, the volume ratio of dinethylformamide and oxolane is: 0.5: 9.5-9.5: 0.5.