Research On Preparation And Property Of Modified Gelatin Gel As Drug-release Material

Gelatin, originated from Collagen, is a natural peptide polymer. There are various active groups in the molecule chain, and because of the high activity of theε-amino group, we can prepare some protein-based materials with special applications by modification. Ethylenediaminetetraacetic dianhydride(EDTAD)is a micromolecule modifying reagent, in this essay, a modified gelatin gel was synthesized by firstly acylating the gelatin with EDTAD, followed by crosslinking with glutaraldehyde. The optimal conditions of the preparation technology were discussed, and the law of the swelling process was studied. The drug-release property and mechanics of the modified gelatin gel with drug-loaded were researched.Firstly, The pretreatments of gelatin solution were discussed, When the gelatin solution was heated at pH10/65℃for 30min, the results showed that it's favored for acylation to pretreat the gelatin solution under these conditions. The effect of acylation on the content of lysyl residue and carboxylic group and the distribution of molecular-weight was studied. The effects of the amount of EDTAD and glutaraldehyde on the swelling ratio of gelatin gels were researched, the optimal swelling ratio was 199.30g/g at m_EDTAD:m_Gelatin=1:15 and m_Gelatin:m_{glutraraldehyde}=50:1. The IR results showed that more carboxyl groups were introduced and the number of amido-link increased after acylating with EDTAD; The SEM photographs showed that the gelatin gel had a more highly ordered and nicer structure by acylating with EDTAD,cross-linking with glutaraldehyde and freeze-dried.Secondly, The property of swelling of Modified gelatin gel and its swelling kinetics were researched, the results showed that when the concentration of the gelatin solution was 13%, the swelling ratio was 199.30g/g. The temperature almost had no impact on the swelling property, and the higher pH and the less concentration of NaCl, the better swelling property the modified gelatin gel had. In the buffers with pH10.04 and 4.30, the gelatin gel appeared pH-sensitivity. The swelling behavior of modified gelatin gel was studied and the results were as follows: the gel appeared Fickian's diffusion behavior in de-ionized water, buffer with pH10.04, non-Fickian's diffusion behavior was presented in the buffers with pH4.30 and pH7.00 and normal saline.On the base of swelling property of modified gelatin proein gel , the drug-release property of gel was discussed. The modified gelatin gel with drug-loaded was obtained in physical absorption method by immersing in the drug solution. The drug-loaded law of modified gelatin gels with different m_EDTAD:m_Gelatin and m_Gelatin:m_{戊二醛} was consistant with the swelling rule, but the swelling property decreased. The drug-release property in vitro was researched. The larger amount of EDTAD, the higer accumulative release ratio the gel had. The pH of the release medium had an evident impact on the drug-release property, while the temperature had little impact. The drug-release kinetics of the gel was studied, it showed non-Fickian's diffusion in buffer with pH1.4, and Fickian's diffusion in buffer with pH7.4.