Preperation And Properties Of Injectable Hydrogels Based On Modified Carboxymethyl Cellulose

As novel polymer materials, injectable hydrogels were widely studied based on its superior applications such as in situ injection, easily operation, minimally invasive, et.al. However, several problems still reminds for some of hydrogels, such as too high concentration hydrogel were not conducive to the actual operation, the gelling time of the hydrogel was necessary to be controlled to avoid clogging needle and drug or activity factor diffusing away quickly before gel formed,the mechanical strength of the hydrogel was too weak to make the structure easily destroy and so on. In view of the above issues, we synthesis and characterization a series of injectable hydrogels based on modified carboxymethyl cellulose, and investigated their application in drug delivery.1. pH and redox dual stimuli-responsive injectable hydrogels were prepared by cross-linking oxidized carboxymethyl cellulose(oxi-CMC) with 3,3'-dithiobis(propionohydrazide)(DTP) via Schiff base reaction under physiological condition. Its structure was characterized by Fourier transform infared(FT-IR) spectroscopy. The gelling time, mechanical strength and the behavior of swelling and degradation with different concentration of oxi-CMC/DTP hydrogels were investigated. Under acidic or reducing conditions, the behavior of swelling and degradation of hydrogels were studied, and BSA as a modle drugs was uitilized to study the release behavior of the hydrogel. These results indicated that a serious of dual stimuli-responsive pH and redox hydrogels were prepared, and the oxi-CMC6/DTP6 hydrogel had better overall performance for injection based on its suitable gelling time and preponderant mechanical properties. Under physiological condition, the oxi-CMC6/DTP6 hydrogel, has a good stability and obvious sustained release ability, was gradated 60% within 2 weeks, and the BSA released 78% within 5 days. The degradation percentage and drug release rate were accelerated in mildly acidic condition and high thiol level media. The oxi-CMC6/DTP6 hydrogel was completely gradated within 5 days, and the BSA completely released within 2 days.2. The thiol-modified carboxymethyl cellulose(CMC-SH) injectable hydrogels were prepared via oxidizing method. The structure of CMC-SH and hydrogel were characterized by FT-IR spectroscopy and 1H NMR. The gelling time, mechanical properties, microstructure, swelling ratio, degradation behavior and drug release behavior with different concentrations of CMC-SH hydrogel were investigated. These results showed that the gelling time of the hydrogel was 2 h via air oxidizing, and the hydrogel can be in situ formed by catalytic oxidation with H2O2. The hydrogel showed a high equilibrium swelling ratio, slow degradation rate, increased crosslinking density and a more densely network structure with the increase content of CMC-SH. The hydrogel exhibits an increased mechanical strength and the yield stress of 3% CMC-SH hydrogel up to 9328 Pa. The released of BSA was mainly controlled by free diffusion, and the hydrogel has good drug slow-release ability. 3% CMC-SH hydrogel has released of the BSA only 48% within 5 days. It could be a promising candidate for drug delivery system and tissue engineering.