CN103751852B - Preparation method of three-dimensional artificial random porous structure tissue engineering scaffold - Google Patents

Abstract

The invention relates to a preparation method of a three-dimensional artificial random porous structure tissue engineering scaffold, belonging to the technical field of biomaterials. The invention aims to solve the design and manufacturing problems of the bionic structure of tissue engineering scaffold, provides a design method for constructing a random distributed scaffold porous structure with a bionic shape under expected porosity and pore size requirements, and molds by using a 3D additive manufacturing method to produce tissue substitute. The preparation method provided by the invention has the following advantages that the scaffold has a 3D through-hole structure meeting bionic requirements, and ensures nutrient substance transfer and waste metabolism and has certain bionic mechanical properties; the porosity and pore size distribution range of the scaffold can be conveniently controlled, and the random pore structure with expected function gradient is constructed to realize the bionic characteristic of the structure; and the method is suitable for a large range of materials such as metal materials, non-metal materials and medical high molecular materials, and can meets user-personalized tissue repair requirements.

Description

The preparation method of the random loose structure tissue engineering bracket of a kind of three-dimensional artificial

Technical field

The invention belongs to technical field of biological materials, be particularly applicable to the preparation of biomedical tissue engineering scaffold material, be specially a kind of design and preparation method of three-dimensional artificial random structure tissue engineering bracket.

Background technology

Organizational project is an emerging Medical Technology, it is the principle art of application life sciences and engineering, correctly be familiar with organizational structure, function on the relation basis normally and under pathology two states, the biosubstitute of research and development for repairing, safeguarding the function and morphology after each injuries of tissues and organs of human body, thus attention.Its core is by biomaterial and cellularity three dimensions complex, its basic skills is by the normal tissue cell of In vitro culture, be adsorbed on a kind of good biocompatibility, biomaterial rational in infrastructure, by the lesion of this cell-biomaterial composites implanting tissue or organ, in vivo under environment, cell carries out various physiological activity on biomaterial, to reach the object of repairing wound.

The key manufacturing tissue engineering bracket is the loose structure manufacturing its inside, and the form of hole directly can affect the growth course of cell.In principle, the function of support is to provide an environment, carrys out irritation cell behavior by the interaction between cell-scaffold, cell-ECM, as: adhesion, migration, propagation, differentiation, maintenance and death.Tissue engineering bracket can realize in vivo or in In vitro culture to the initial support of tissue, initially the sticking and make cell can controllably formative tissue or organ of cell.Desirable support should have these features: 1) there is the high porosity loose structure be connected inside, and can adapt to Growth of Cells, the conveying of nutritional flow and the discharge of metabolite; 2) the degradable speed that there is biocompatibility, match with tissue growth; 3) Surface chemical characteristic of cell adhesion, propagation, differentiation is promoted; 4) mechanical property matched with surrounding tissue.

Anisotropic porosity can guide bone to regenerate along the direction of porosity and mechanical strength gradient, and this can control differentiation of stem cells, and then promotes function of organization.Different pore structures can affect near and away from the direction of motion of the cell of this structure and speed, this becomes a kind of physiological mechanism that extracellular environment controls cell behavior.The random pore structure with certain porosity is through the ideal structure of Natural Selection and Evolution.It has more superior mechanical property and permeability than regular porous structure, have more multifarious pore morphology to adapt to the difference needs of cell, certain mechanical strength requirement can be taken into account while ensureing certain porosity, and its 3D interconnected pore, nutrient substance is convenient to pour into into internal stent, and discharge cellular metabolism refuse, build the environment being beneficial to Growth of Cells.

At porous support manufacture view, although more existing traditional manual manufacture methods are as salt Filtration, gas foaming method, freeze-drying, but these methods only can realize, to the coarse adjustment of a small number of parameters (as: porosity, pore-size), cannot finely controlling.The increasing material manufacturing technology that latest developments are got up, as technology such as selective laser sintering, laser fast shaping, free entity manufacture, 3D printing, stereolithography, solves this problem and is successfully applied to molding complex parts.Now, these technology are also introduced into field of tissue engineering technology, result proves that this technology is potential for the manufacture of more complicated, the high pore structure of bionical feature and the support product of mechanical characteristic, and accurately can form the microscopic pattern of support, control somatomedin spatial distribution, with the needs of satisfying personalized tissue repair.

At present, still there is a lot of difficulty in the design & formulation method for the random porous support increasing material manufacture, as: how to design there is bionical performance random distribution loose structure, how automatically decision throughout the fundamental (position and shape) in irregular hole, the pore size distribution how controlling this structure further and porosity distribution to meet bionical needs etc.The bottleneck that these difficulties become the design of restriction biomimetic features tissue engineering bracket, manufacture and apply.

Summary of the invention

The object of the invention is that solving traditional design method flexibly, accurately can not build random loose structure, and the problem such as traditional preparation methods cost is high, technique is unstable, pore creating material is residual, support intensity is low, the preparation method of the tissue engineering bracket of the random loose structure of a kind of three-dimensional artificial is provided.

The preparation method of the tissue engineering bracket of the random loose structure of three-dimensional artificial provided by the invention, based on three reset cycle minimal surfaces (triply periodic minimal surface, be called for short TPMS) the random loose structure of method design, and adopt increasing material manufacture method to prepare this support, the concrete steps of the method are:

1st, set up the inside and outside model of 3D digitized of artificial random loose structure support, step is:

A, structure random function, make function value in the claimed range of the porosity of natural bone, pore-size;

B, to be substituted into by random function in porosity control item in TPMS Implicitly function and pore-size control item, the external morphology structure of support is controlled by constructed TPMS Implicitly function, sets up the digitized internal structure model of support 3D;

C. according to the external shape data of natural fabric or the shape data of artificial implantation, the 3D digitized outer surface model of support is set up.

D. the outer surface model that internal structure model b step set up and c step are set up combines, and final generated physical model is derived with STL form, increases material manufacture process in order to instruct follow-up 3D.

2nd, 3D is adopted to increase the artificial random loose structure support of material manufacture method preparation.

Described 3D increases material manufacture method and comprises: selective laser sintering process, free entity autofrettage, 3D impact system, and stereolithography method.As: selective laser sintering, the steps include:

Work platforms is spread the biomaterial powder of a thin layer, the powder in model appointed area, specific region is only sintered by computer control laser head, this one deck has sintered, computer parametric controller moves down the distance of a thin layer, again spread powder, the lower one deck of sintering, namely support is shaped by this accumulation mode in layer, the advantage of this technology is: powder can serve as supporting construction to support the molding of last layer, therefore can manufacture 3D pore structure complicated arbitrarily.

This support has good hole connectedness and random distribution form as tissue substituent, is beneficial to cell and obtains nutrient substance and discharge refuse, take into account certain mechanical strength, for cell provides optimum 3D growing space simultaneously.Choice of powder form material of the present invention is as shaping raw material, alternate material is extensive, comprise metal, nonmetal and medical macromolecular materials etc., be specially: titanium, magnesium, bioactivity glass, hydroxyapatite and biocompatible polymer material (as: polylactic acid and polymer, PGA, polylactic acid-PGA copolymer, polycaprolactone, poly-β-hybroxybutyric acid, poly-β-hybroxybutyric acid-poly-hydroxyl pentanoate copolymer, polycaprolactone-polyethylene glycol segmented copolymer or polyurethane).

Advantage of the present invention and beneficial effect are:

Adopt the mode of computer-aided design, design has the tissue engineering bracket of bionic function, random pore structure, and accurately manufactures this cell structure by increasing material manufacture method, can realize the support preparation of user individual.Porosity control item in three reset cycle minimal surface Implicitly function and pore-size control item can control the distribution of brace aperture rate and pore-size easily, and then there is the random porous support materials expecting Pore genesis exactly, and by changing each control item, the random pore structure having and expect gradient can be built easily, to realize various bionical characteristic.Meanwhile, the 3D adopted increases material manufacture method accurately can go out desirable product according to model manufacturing.Suitable material of the present invention is extensive, and in current organizational project, widely used metal material, nonmetallic materials and the multiclass macromolecule polymer material with biologically inert/activity can adopt mode of the present invention to be shaped.Products made thereby has: the entirety connectedness of hole and entity, form randomness, functionally gradient take into account the porosity of anthropoid tissue/organ, aperture and biomechanical property.Both as having the guiding of excellent osteogenesis, the embedded material use of inducibility, can be applied to scientific research again: the delicate change controlling internal stent structure, investigating the growth demand which kind of porous form support can meet specific cells.

Accompanying drawing explanation

Fig. 1 is the artificial random loose structure cubic support structure of the present invention and median elevation layer slice map (a), and with the comparison diagram of regular porous structure and section (b).

Fig. 2 is the artificial random loose structure cubic support finished product Sum fanction structure stand comparison diagram of the present invention.

Fig. 3 is artificial joint component outline dimensional drawing.

Fig. 4 is this joint component 3D illustraton of model adopting the present invention program.

Detailed description of the invention

Embodiment 1

The preparation method of the tissue engineering bracket of the random loose structure of three-dimensional artificial provided by the invention, based on the random loose structure of three reset cycle minimal surface method design, and adopt increasing material manufacture method to prepare this support, concrete steps are:

1st, set up the inside and outside model of 3D digitized of artificial random loose structure support, step is:

A, distribution structure random function according to the porosity of natural fabric, pore-size, make function value in this distribution;

In cube, be sprinkled into the 3D point of t=27 regular distribution, each point coordinates be (t1 [il, i2 [il, x3 [and il), structure random function:

$f(x,y,z)=\underset{i=0}{\overset{t-1}{\mathrm{\Σ}}}h\left(i\right)\mathrm{Sin}\left(\frac{{(x-x1[i\left]\right)}^2+{(y-x2[i\left]\right)}^2+{(z-x3[i\left]\right)}^2}{30}\right)---\left(1\right)$

Wherein h [i] is equally distributed random real number between-1 and 1.

Solve following constrained optimization problem:

Min(Max)f(x，y，z)

s.t.0≤x≤26

0≤y≤26

0≤z≤26 (2)

Wherein: the size of cubic support length is 26mm.Try to achieve the solution of above problem, make maximum be Iila, minima is min.Make d1=2.32, d2=3.48 is the coefficient a in (4) formula that required pore diameter is corresponding when maximum, minimum, b, the value (here a=b=c) of c, make k=(d2-d1)/(max-min), m=d2-kmax is two linear transfor coefficients, constructs new random function:

g(x，y，z)＝kf(x，y，z)+m (3)

Its codomain must between d1, d2.

B, to be substituted into by random function in porosity control item in three reset cycle minimal surface Implicitly function and pore-size control item, the external morphology structure of support is controlled by three constructed reset cycle minimal surface Implicitly function:

Select G shape three reset cycle minimal surface Implicitly function:

θ (ax, by, cz, p)=Cos (ax)+Cos (by)+Cos (cz)+p (4) wherein a, b, c is pore-size control item, p is porosity control item, θ (ax.by, cz, p)≤0 represents the space that internal stent is full of solid material, and other is interstitial space.

By a=b=c=g (x, y, z), p=0 substitutes into (4) formula, can be 1000-1500 μm by pore size control, hole

It is about 50% that rate controls.

C, according to the external shape data of natural fabric or the shape data of artificial implantation, set up the 3D digitized outer surface model of support;

This shape data is cubical area, the constraints namely in formula (2):

s.t.0≤x≤26

0≤y≤26

0≤z≤26

The outer surface model that d, internal structure model b step set up and c step are set up combines, and final institute generation model saves as STL form and derives, and increases material manufacture process in order to instruct follow-up 3D;

2nd, stl file is imported 3D printer or rapid prototyping machine input system, select the material of expectation, the artificial random loose structure support consistent with model structure can be prepared.

The inventive method is adopted to carry out computer-aided design, 3D designs a model as shown in Figure 1 (section is got at median elevation place, is convenient to show its 2D feature), as can be seen from Figure 1, random pore has more diversified pore structure compared with regular hole, all has anisotropy everywhere.This model is derived with STL form, and input increases material manufacturing system, and adopt 2D layer accumulation mode to prepare artificial random loose structure cubic support finished product, result is as Fig. 2, and this cube adopts ABS resin material, is of a size of 26 × 26 × 26mm ³, aperture is 1000-1500 μm, and porosity is about 50%.

Embodiment 2

Fig. 3 is the design outline figure (specific design process is see embodiment 1) of artificial joint component, requirement material is Titanium, wherein half outer surface of ball radius 32mm, inner surface radius 26mm, inside and outside spherical surface eccentric throw is 5.5mm, connects cylindrical drum thickness consistent with shell thickness under spherical shell, outer surface, inner surface height are respectively 7mm, 12.2mm, spherical shell top punching Ф 3mm, has the hole Ф 6mm of 6 equidistant annular arrays around it, this axis cross the spherical outside surface centre of sphere and with bottom surface angle 50 °.Require that top layer distributes random loose structure, internal layer is entity structure.According to the present invention program design 3D model as shown in Figure 4, porose layer thickness 3mm, all the other are physical layer, and porosity is about 67%, aperture 1-1.5mm, have aperture layer and physical layer one integrated mass, therebetween without any interface.

Embodiment shows, of the present invention design a model can flexibly, automatically, accurately in conjunction with random loose structure and external shape, settle at one go and avoid secondary operations, porosity required by guarantee and pore-size, 3D is coordinated to increase material manufacture method, accurately can produce the supporting structure of model requirement, to meet the needs of bionical personalization.

Claims (1)

1. the preparation method of the tissue engineering bracket of the random loose structure of three-dimensional artificial, the method is based on three reset cycle minimal surface triply periodic minimal surface, be called for short the random loose structure of TPMS method design, to adopt increasing material manufacture method to prepare this support, concrete steps are:

1st, set up the inside and outside model of 3D digitized of artificial random loose structure support, step is:

A, structure random function, make function value in the claimed range of the porosity of natural bone, pore-size;

B, to be substituted into by random function in porosity control item in TPMS Implicitly function and pore-size control item, the external morphology structure of support is controlled by constructed TPMS Implicitly function, sets up the digitized internal structure model of support 3D;

C, according to the external shape data of natural fabric or the shape data of artificial implantation, set up the 3D digitized outer surface model of support;

The outer surface model that d, internal structure model b step set up and c step are set up combines, and generates final physical model and increases material manufacture process in order to instruct follow-up 3D;

2nd, 3D is adopted to increase the artificial random loose structure support of material manufacture method preparation.