A Study Of The Preparation And The Properties Of Temperature And PH Sensitive Chitosan Nanogel

Objectives To synthesize p H- and temperature- sensitive nano-hydrogels using NIPAAm and CS and research the properties of the nano-hydrogel.Methods Firstly, PNIPAAm-OH with different molecular weights was prepared by the controlled polymerization technique using NIPAAm as material; then PNIPAAm-AA monomer was synthesized using PNIPAAm-OH; and six kinds of p H- and temperaturenano-hydrogels with semi-interpenetrating network structure were obtained using different feeding amount of PNIPAAm-AA and CS. The properties of the nano-hydrogel were researched, including swelling ratio test, LCST measurement, IR spectra, particle size analysis and transmission electron microscopy. The drug loading and in vitro drug release experiments was carried out using MG2 nano-hydrogel according to the results of the previous five performance test. The cytotoxicity of MG2 nano-hydrogel on L929 cells was evaluated using MTT assay preliminarily, and the effect of MG2 nano-hydrogel on apoptosis of L929 cells was also studied, then the toxicity of MG2 nano-hydrogel was evaluated by the results of these two experiments.Results 1 The feeding amounts of ME increase, the molecular weight of PNIPAAm-AA will decrease, and the hydrophilicity will decrease likewise in controlled polymerization. 2 The obtained six kinds of nano-hydrogels with semi-interpenetrating network structure have p H and temperature sensitivity. 3 LCST values of the hydrogels increase, with the increasing of CS feeding amount. 4 The encapsulation efficiency of MG2 nano-hydrogel was 74% and the drug loading rate was 9.65%. 5 The in vitro drug release curve of MG2 nano-hydrogel showed that: The drug release speed and drug release rate were different under the different temperature and p H values. 6 The MTT toxicity test and apoptosis experiment together suggested that: the MG2 nano-hydrogel has little effect on the proliferation of L929 cells,and.it has has a certain effect on the apoptosis of L929 cells.Conclusions 1 The obtained six kinds of nano-hydrogels all have pH and temperature sensitivity. 2 Transmission electron microscopy show that: The morphology of MG2 nanohydrogel was the best, and the drug release speed and drug release rate of MG2 hydrogel were different under the different temperature and p H values. 3 MG2 nano-hydrogel has little effect on the proliferation of L929 cells, andhas has a certain effect on the apoptosis of L929 cells, which needs further study on the toxicity of the materials.