A kind of preparation method of nano natural silk protein powder
Technical field
The present invention relates to a kind of method of utilizing natural silk to prepare nano level silk fibroin powder, belong to function nano material technology field.
Background technology
The function nano material is field the most dynamic in the nanometer material science, and it can be applied to high-tech areas such as chemical industry, biology, the energy, environment, and the generation far-reaching influence also has broad application prospects.Can be applied in fields such as organizational project, regenerative medicine material and physiologically acceptable boundary material as nano meter biomaterial.When the application of physiologically acceptable boundary material, it mainly is to pass through laminated assembling technology, realization comprises that protein, DNA and polyelectrolyte etc. are in the assembling on numerous base materials under the condition of gentleness, not only realized structural simulation to natural biologic material, and can obtain surperficial stratiform biomaterial, solve the biocompatibility key issue of some materials, can be applied to as cell growth support, medicament slow release material, enzyme and scopes such as imitative enzyme carrier and bio-sensing modulator material.And the nanometer chemical materials, can add by chemical reaction or physics give chemical materials such as degraded, catalysis, smelly function such as antibiotic disappears.
Just because of the function nano material has great using value, how to prepare and just Cheng Liao expert, scholar's research focus of application function nano material.Natural silk is to be made of special amino acid, and it has possessed the very big using value as biology, weaving, fine chemistry industry material, and is very active to the preparation technology and the method research of its nano level silk fibroin powder.The present industrial nano level silk fibroin powder, preparation method thereof that still do not have, the industrial now situation that has the employing mechanical crushing method to prepare silk fibroin powder, but be subjected to the restriction of size reduction machinery technology, can only make micron particles, and micron particles and nano-scale particle, its range of application and effect are inconsistent.For the preparation of silk fibroin powder nano-scale particle, all be in laboratory stage at present.Such as application number is " 200610039191.8 "; denomination of invention discloses so a kind of method for the Chinese invention patent application of " silk nano granular of immobilized enzyme and preparation method thereof "; it has adopted water-soluble fibroin solution and can mix with miscible proton type organic solvent or the aprotic, polar type organic solvent of water; forming milky spherical particle is dispersed in the organic solvent system; obtain nano thread crude granule mixed solution or suspension; remove organic solvent; obtain silk nano granular suspension or fibroin nanometer powder, the nano particle that makes is about 35~125nm.In this method, insoluble or be insoluble in water as fibrinous silk fibroin, and do not point out the preparation method of water-soluble fibroin solution in this patent, simultaneously water-soluble fibroin solution with can with water miscible proton type organic solvent or aprotic, polar type organic solvent mixing process in, the fibroin stripping is low, loss is big, and the preparation difficulty is big, yield is low, be difficult to industrialized deficiency so exist.Also has a Chinese invention patent (patent No. is that " 200410016856.4 ", denomination of invention are " fibroin Nano microsphere and preparation method thereof ") utilization biological nano technology, make silk protein that self-assembly take place under proper condition and form Nano microsphere, the nano particle that makes is about 80~3000nm.This method also exists the preparation difficulty big, is difficult to industrialized deficiency, and also there is big, the uneven problem of nano particle difference in size in this patent simultaneously.
The patent No. is that " 02138016.3 ", denomination of invention also disclose a kind of method for preparing silk fibroin for the Chinese invention patent of " a kind of preparation method of bioactive peptide-silk fibroin peptide ", it is a raw material with leftover bits and pieces silk cocoon or useless silk, through the Na of 0.3-1.0% (w/v)
2CO
3After solution is concise, with the CaCl of 20-60% (w/w)
2The solution heating for dissolving gets molten silk liquid, at pH2.5-12.0, with proteolytic enzyme molten silk liquid is carried out enzymatic hydrolysis reaction under 30-80 ℃, removes the CaCl of enzymolysis solution middle and high concentration again with nanofiltration
2Salt, to the concentrated solution spraying drying promptly.Though this method can make the silk fibroin powder, particle is big, can't reach nano level, and this is because CaCl
2This metal-salt, the Ca ion can be wrapped in the fibroin by complexing when the dissolving fibroin, also the Ca ion can't be removed even if carry out aqueous solution dialysis, and this technology is not remove CaCl
2Situation under the enzyme digestion reaction that carries out, except the formation of fibroin-Ca ionic complex has influenced enzyme digestion reaction, has reduced the hydrolysis result CaCl
2Existence in whole enzymolysis system also will make its Ca ion and proteolytic enzyme form chelation structure, make enzyme digestion reaction be difficult to normally carry out thereby cause enzyme to lose activity.Be to remove CaCl behind the first enzymolysis
2Technical process, be the purpose that can't reach preparation nano level silk fibroin powder.
Summary of the invention
At the prior art above shortcomings, the purpose of this invention is to provide a kind of method of utilizing natural silk to prepare nano level silk fibroin powder, present method is simple for process, be fit to industrialization, production in enormous quantities, gained protein powder uniform particles is of moderate size, and is beneficial to application.
The object of the present invention is achieved like this: a kind of preparation method of nano natural silk protein powder is characterized in that it may further comprise the steps:
1., purified fibroin raw material added carries out in the salts solution of capacity that salt is molten to obtain molten silk liquid, described salts solution is 50~60wt%NaSCN or by LiBr, CH
3OH and H
2O three is by weight 40~60: 22~42: 10~30 organic-inorganic mixed solvents that are made into;
2., molten silk liquid that the first step is obtained dialyses, and obtains silk fibroin water solution;
3., second silk fibroin water solution that obtain of step is carried out enzymolysis, enzymolysis proteolytic enzyme is Chymetin or neutral protease;
4., the dry collection of enzymolysis solution promptly got silk fibroin powder.
The preparation method of described fibroin raw material is: will discard cocoon shell or waste silk and soak to remove waxy substance (discarded cocoon shell immersion 48 hours wherein with ether compound, waste silk soaked 24 hours), wash with water to boil with ethanol again after the drying and removed carbohydrate and ash content in 1 hour, after cleaning, in water, boil again, wash the pure fibroin that obtains with water drying for standby to slough silk gum.
Described enzyme solution is: silk fibroin water solution is heated in 70~80 ℃ of water-baths takes out behind the 5min and adjust pH, add the proteolytic enzyme of enzymolysis aequum, stir hydrolysis to the enzymolysis desirable value, through after certain reaction times with the enzyme deactivation stopped reaction.
If enzymolysis proteolytic enzyme is Chymetin, then the pH value transfers to 5.5~7.5 with 25% ammonia solution, add proteolytic enzyme 37 ℃ ± 3 ℃ stir the about 1~1.5h of hydrolysis down after, solution is put into-40 ℃ and is frozen the storehouse and allow the enzyme deactivation stopped reaction.
If enzymolysis proteolytic enzyme is neutral protease, then the pH value transfers to 6.0~7.5 with 25% ammonia solution, add proteolytic enzyme 50~55 ℃ stir the about 1~1.5h of hydrolysis down after, solution is put into-40 ℃ and is frozen the storehouse and allow the enzyme deactivation stopped reaction.
Compare prior preparation method, the present invention has following beneficial effect:
1, because Chymetin or neutral protease have the enzyme of silk fibroin is cut strong, the even advantage of enzyme chopping fibroin of function, so the silk fibroin uniform particles that obtains is of moderate size, be beneficial to application, granular size is 80~500nm.This nano thread fibroin can be used as cosmetics additive less than the human skin pore size.
2, present method technology is simple, is easy to realize that the single preparation amount is big, and is raw materials used for discarded silk, for the leftover bits and pieces raw material utilizes category again, possessed the application prospect in field of functional materials.
3, salts solution and the enzymolysis protein enzyme low price selected for use of present method, preparation cost is low.
4, yield height of the present invention can reach 65~80%.
Based on above-mentioned advantage, so the present invention can carry out in enormous quantities, suitability for industrialized production.
Experiment shows that the nano thread fibroin powder of present method preparation has anti-microbial property, can be used as biomaterial and uses, and also can be used as functional fiber and substance thereof, and the while also can be used as the food interpolation, the fine chemistry industry goods add material and are applied.
Description of drawings
The protein powder particle that Fig. 1-the present invention uses the Chymetin enzymolysis to obtain;
The protein powder particle that Fig. 2-the present invention uses neutral protease enzymolysis to obtain;
Fig. 3-sample is cultivated the fungistatic effect figure behind the staphylococcus aureus on every side.
Embodiment
The present invention is with 50~60wt%NaSCN salts solution or LiBr, CH
3OH and H
2(weight ratio 40~60: 22~42: 10~30) mixed solvent that is made into of three dissolves silk fibroin to O, carry out the enzymolysis refinement with Chymetin or neutral protease again after dialysis concentrates and prepare evengranular nano thread fibroin powder, its nano particle size is 80~500nm.With the nano-grade silk silk fibroin powder uniform particles that present method makes, technology is simple, and is raw materials used for discarded silk, for the leftover bits and pieces raw material utilizes category again, possessed the application prospect in field of functional materials such as biomaterials.
Introduce the present invention in detail below in conjunction with embodiment.
1. at first obtain the fibroin fiber raw material
Discarded cocoon shell or waste silk are soaked to remove waxy substance (discarded cocoon shell immersion 48 hours wherein with ether compound, waste silk soaked 24 hours), wash with water to boil with ethanol again after the drying and removed carbohydrate and ash content in 1 hour, after cleaning, in water, boil again, wash the pure fibroin that obtains with water drying for standby to slough silk gum.After purifying with carmine picric acid solution method check silk gum, wash the pure fibroin that obtains with water drying for standby.
The preparation of fibroin is not limited to aforesaid method, also can adopt traditional other fibroin preparation method to obtain.
2. the preparation of silk fibroin water solution
The salts solution of dissolving fibroin fiber can be by weight 40~60: 22~42: 10~30 (best proportioning is 50: 32: 10) preparation LiBr, CH
3OH and H
2The organic-inorganic mixed solvent that O three forms also can be 50~60wt%NaSCN salts solution.The pure fibroin fiber that obtains in the last step is dissolved in the solvent of preparing above.The amount of salts solution gets final product fully dissolving fibroin fiber.
3. stand-by after dialysing, concentrating.
4. regenerated silk protein powder enzymolysis (enzymolysis can adopt two kinds of proteolytic enzyme, and a kind of is Chymetin, and a kind of is neutral protease)
(1) enzymolysis of Chymetin: through fixed molten and mensuration, the used silk fibroin peptide solution of the present invention concentration is all in 2~5mg/ml scope.Take out after the beaker that silk fibroin water solution is housed is placed in 70~80 ℃ of water-baths heating 5min, solution is adjusted pH to 5.5~7.5 with 25% ammonia solution, according to silk fibroin: the Chymetin weight ratio is (in reality also can adopt other ratio add at 10: 1, as long as the add-on of enzyme can be guaranteed the abundant enzymolysis of silk fibroin powder) ratio add Chymetin, 37 ℃ down stir the about 1.5h of hydrolysis after, solution is directly put into-40 ℃ and is frozen the storehouse and allow the enzyme deactivation stopped reaction.The silk fibroin powder evaporates down at 60 ℃ with the centrifugal back of whizzer and obtained dried powder in 48 hours behind the enzymolysis.Yield about 65~80%.The size of powder is observed and is undertaken by field emission scanning electron microscope, observes it for big or small ball-type powder between the 80nm to 500nm, sees figure one, and a and b are the sectional drawing of different positions.
(2) enzymolysis of neutral protease: through fixed molten and mensuration, the used silk fibroin peptide solution of the present invention concentration is all in 2~5mg/ml scope.Take out after the beaker that silk fibroin water solution is housed is placed in 70~80 ℃ of water-baths heating 5min, solution is adjusted about pH to 6.0~7.5 with 25% ammonia solution, according to silk fibroin: the neutral protease weight ratio is (in reality also can adopt other ratio add at 10: 1, as long as the add-on of enzyme can be guaranteed the abundant enzymolysis of silk fibroin powder) ratio add neutral protease, 50~55 ℃ down stir the about 1.5h of hydrolysis after, solution is directly put into-40 ℃ and is frozen the storehouse and allow the enzyme deactivation stopped reaction.The silk fibroin powder evaporates down at 60 ℃ with the centrifugal back of whizzer and obtained dried powder in 48 hours behind the enzymolysis.Yield about 65~70%.The size of powder is observed and is undertaken by field emission scanning electron microscope, observes it for big or small ball-type powder between the 80nm to 500nm, sees figure two, and a and b are the sectional drawing of different positions.
The silk fibroin powder can also adopt freeze-drying to collect except above-mentioned centrifugal back evaporation drying collection obtains.
Antibacterial experiment
Use extractum carnis, peptone, sodium-chlor, water to make substratum.Agar powder is the inoculation streptococcus aureus after the dissolving sterilization, maconkey agar inoculation intestinal bacteria.
Cultured intestinal bacteria and streptococcus aureus are taken out, coating method is inoculated into culture dish respectively with two kinds of bacteriums, silk-protein peptide powder, zinc phthalocyanine powder and zinc phthalocyanine-silk fibroin peptide powder is distinguished inoculation culture 18 hours, observe the growing state of bacterium.Entire operation is all carried out at the aseptic technique platform.
Experiment shows, the nano natural silk protein powder of the present invention's preparation possesses stronger anti-microbial property, shown in figure three, wherein scheming a is the silk fibroin peptide powder antibiogram that 50~60wt%NaSCN dissolving obtains, and figure b is the silk fibroin nanometer powder antibiogram behind the enzymolysis.