CN1296852A - Chitosan/gelatin network modification on surface of aliphatic polyester - Google Patents

Abstract

One uses N-carboxymethyl chitosan and gelatin as modifiers to modify the surface of polylactic acid by alkaline direct activation method, and introduces cell active groups on the surface of polylactic acid to prepare chondrocyte scaffold material. Since chitosan is an alkaline polysaccharide, it degrades with polylactic acid at the same time, and can also inhibit the pH pulse effect on the environment during the degradation of polylactic acid, and improve the cell affinity of the surface of polylactic acid materials.

Description

Chitosan/Gelatin Network Modification on the Surface of Aliphatic Polyester

The invention belongs to biomedical engineering

Tissue engineering is an emerging discipline that uses the basic principles and methods of engineering science and life science to research and develop biological substitutes to restore, maintain and improve tissue functions. It is to separate and cultivate cells in vitro, plant a certain amount of cells into a three-dimensional biomaterial skeleton with a certain shape, and continue to cultivate them, and finally form tissues and organs with a certain structure and implant them back into the body to achieve repair and/or reconstruction. Purpose. Most of the current work is based on synthetic materials, especially polylactic acid as the base material as the scaffold material. Studies have shown that the surface of polylactic acid materials lacks cell binding sites. [Rouhi A M,ContemporaryBiomaterials,Understanding surfaces is key to the design of clinically useful materials,Chem.Eng.News,1999,77(3):51-59] and its degradation product is acidic, and the pH pulse effect of the product is to a certain extent [Peppas H A, Langer R, New challenges in biomaterials, Science, 1994, 263:1715-1720; Lam K, Esselbrugge H, Schakenrad J, Biodegradable of porous versus non-ourous poly(L-lactic acid) film, JMater Sci: Mater Med, 1994, 5(2):101-110]. Tatsuro Ouchi et al introduced sugar chains through chemical modification of the surface functional groups of poly[(lactic acid-co-glycolic acid)-lysine] microspheres, endowing them with cell recognition function [Yuichi Ouchi, Tatsuro Ouchi, Biodegradable Biomaterialsとしこの新しじポリ Lactic Acid-Based Polymers, Polymer Processing, 1999, 48(12):530-534]. Its disadvantages are: cytotoxic reagents are easy to remain in the reaction process, and the steps are cumbersome and difficult to operate; on the other hand, the pH pulse in the degradation process of polylactic acid is not considered to be suppressed. Tetsuji Yamaoka et al used direct activation method under alkaline conditions to modify the surface of polylactic acid with gelatin. However, Yamaoka et al. also did not consider to suppress the impact on the surrounding environment after the acidic degradation of PLA. The disadvantage of the above method is that it does not consider the use of chemical surface modification of highly toxic reagents and the pH pulse effect of inhibiting the degradation of polylactic acid from the perspective of composite bionics.

The object of the invention is to use N-carboxymethyl chitosan and gelatin as modifiers, and adopt an alkaline direct activation method to modify the surface of polylactic acid. Not only can a relatively simple method be used to introduce cell active groups on the surface of polylactic acid, but also chitosan is an alkaline polysaccharide, which can be degraded simultaneously with polylactic acid, and can also play a role in the pH pulse of the environment during the degradation of polylactic acid. To the inhibitory effect, overcome the problems existing in the prior art.

The content of chitosan/gelatin network modification on the surface of aliphatic polyester of the present invention is: preparation concentration is the chloroform solution of 1 (wt)%～10(wt)% polylactic acid, casts it into film, then deionized After washing with water, dry at 40°C to obtain a polylactic acid film. Prepare 2 to 7 (wt)% N-carboxymethyl chitosan aqueous solution with a concentration of 0.1 to 2 mol/l NaOH aqueous solution, add gelatin in a ratio of chitosan to gelatin mass ratio of 1:5 to 5:1, Stir slightly under the condition of 45°C for 2-4 hours to obtain an alkaline solution of N-carboxymethyl chitosan-gelatin. The polylactic acid film is immersed in the alkaline solution of N-carboxymethyl chitosan-gelatin, and stirred at 45 DEG C for 0.5-4 hours. The film is taken out, rinsed with deionized water for 3 to 10 times, and dried at 40° C. for 1 to 3 hours. Then, the modified film is treated with ⁶⁰ Co rays for 2-10 hours, with a cumulative dose of 100,000-800,000 rads to achieve sterilization. The film is sealed with a polyethylene film before use.

The invention adopts the natural degradable biological material with good cell compatibility to modify the surface of the synthetic biological material polylactic acid. Its outstanding advantages are that on the one hand, it introduces cell binding sites for the surface of the material; on the other hand, it can adjust the hydrophilic/hydrophobic balance of the surface of the polylactic acid material through the degree of reaction; and the introduction of chitosan can inhibit the environment during the degradation of polylactic acid. The pH pulse effect, the modification method can improve the cell affinity of the surface of the polylactic acid material.

Example:

Take 0.5 g of medical polylactic acid with a molecular weight of 10.8×10 ⁴ and a degree of left-handedness of 98%, and put it into an Erlenmeyer flask, add 10 ml of chloroform, and place it at room temperature for 12 hours to completely dissolve the polylactic acid. Transfer the solution into a 120cm glass petri dish, put it into a vacuum drying oven, and keep the air pressure in the drying room less than 50μatm for 12 hours. After casting into a film, it was rinsed with deionized water, and then dried at 40° C. to obtain a polylactic acid film. The film formed by casting was removed, washed repeatedly with deionized water, placed in an oven, and kept at 40° C. for 4 hours to obtain a solvent-free polylactic acid film. Prepare 2 (wt)% N-carboxymethyl chitosan aqueous solution with 50ml concentration of 1mol/l NaOH aqueous solution, add gelatin according to the ratio of chitosan to gelatin mass ratio of 1: 1, stir gently at 45°C After 4 hours, an alkaline solution of N-carboxymethyl chitosan-gelatin was obtained. The polylactic acid film was immersed in the alkaline solution of N-carboxymethyl chitosan-gelatin, and stirred at 45°C for 4 hours. The treated film was taken out, rinsed three times with deionized water, and dried at 40° C. for 3 hours. Then, the modified film is irradiated with ⁶⁰ Co rays for 2 to 10 hours, with a cumulative dose of 100,000 to 800,000 rads to achieve sterilization, and the polylactic acid modified by N-carboxymethyl chitosan and gelatin is obtained. Film, the prepared polylactic acid film is sealed with a polyethylene film for use.

Claims (3)

1, a kind of chitosan/gelatin network modification method, the invention is characterized in that the aqueous slkali that polylactic acid film is immersed N-carboxymethyl chitosan-gelatin handles, again the polylactic acid film after the modification is adopted the 60Co ray to carry out handling in 2～10 hours, the irradiation of accumulative total 10～800,000 rad doses is to reach sterilization, and is with polyethylene film that this polylactic acid film sealing back is stand-by.

2, chitosan according to claim 1/gelatin network modification method, the preparation that it is characterized in that polylactic acid film is that first compound concentration is the chloroformic solution of 1 (wt) %～10 (wt) % polylactic acid, behind the casting film-forming, behind deionized water rinsing, under 40 ℃ of conditions, dry, make polylactic acid film.

3, chitosan according to claim 1/gelatin network modification method, it is characterized in that it is to be the N-carboxymethyl chitosan sugar aqueous solution of NaOH aqueous solution preparation 2～7 (wt) % of 0.1～2mol/l with concentration that aqueous slkali that polylactic acid film immerses N-carboxymethyl chitosan-gelatin is handled, add gelatin in chitosan and 1: 5 to 5: 1 ratio of gelatin mass ratio, gentle agitation is 2～4 hours under 45 ℃ of conditions, obtain the alkaline solution of N-carboxymethyl chitosan-gelatin, polylactic acid film is immersed the aqueous slkali of this N-carboxymethyl chitosan-gelatin, under 45 ℃ of conditions, stirred 0.5～4 hour, thin film is taken out, with deionized water rinsing 3～10 times, what dry 1～3 hour carried out under 40 ℃ of conditions.