The Study Of Drug Delivery Nanospheres Based On Amphiphilic Chitosan Composite

Currently, the malignant tumor is one of the great threats to human’ health. More and more people are killed by cancer every year, so how to cure cancer is a great challenge for both medical and scientific researchers. The traditional medication can relieve symptoms in some degree, but it can not prevent the cancer metastasis effectively, for the small molecular anticancer drug are prone to accumulate in vivo and they can bring about drug resistance, leading to side-effects. Drug carriers have brought the greatest gospel for medications of cancer treatment. Especially the polymer drug carriers can be decomposed into nutritional ingredients by normal metabolism, because some of these materials are natural polymers with excellent biocompatibility and biodegradability. At the same time, they also have some other advantages such as high loading rate, targeted delivery, controling release and so on. Thus, they can provide the solid foundations for curing cancer.In the study, we chose the biocompatible and biodegradable materials chitosan(CS), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)(PHBHHx) and methoxy polyethylene glycol prepared the diblock copolymers PHBHHx-b-mPEG and the graft copolymers chitosan graft PHBHHx-b-mPEG by a series of chemical modifications. The graft copolymer CS-g-(PHBHHx-b-mPEG) not only retains the original biological chemical activity of chitosan, but also gives its good hydrophilicity. The structure and morphology of products were characterized by FT-IR, 1H NMR, GPC and SEM ect, the average grafting rate of graft copolymers is 20.63% tested by elemental analysis.In order to enhance the stability and drug cladding rate of the chitosan based graft copolymers, we took full advantages of chitosan’s properities as the cationic polyelectrolyte. Firstly the CS-g-(PHBHHx-b-mPEG) were compounded with acrylic acid(AA) by electrostatic interactions, then AA were initiated by K2S2O8(KPS) obtaining the polyacrylic acid(PAA) and CS-g-(PHBHHx-b-mPEG) complex, finally the complex were cross-linked by glutaraldehyde. We find the particle size increased with the increase of pH values in solutions, which is also confirmed by the results of SEM and TEM. The experimental results indicate that the PAA-CS-g-(PHBHHx-b-mPEG) complex particles present clear core-shell structures whether in acidic, neutral or alkaline environments. So this study provides a good foundation and thinking for the preparation of chitosan based anticancer drug carriers with high load rate.