Studies on the preparation and characterization of immobilized neutral protease by carboxymethyl chitosan microsphere / 生物医学工程学杂志

AS1. 398 neutral protease was immobilized onto carboxymethyl chitosan with glutaraldehyde as cross-linking agent. The effects of pH, time of cross-linking, amount of cross-linking agent and the ratio of enzyme to carrier on the activity of the immobilized enzyme were demonstrated, and the optimum immobilization condition of AS1. 398 neutral protease was established. Also studied was the characterization of immobilized enzyme,including pH, temperature, Km and the stability of storage.

Study on preparation of the pH sensitive hydroxyethyl chitin/poly (acrylic acid) hydrogel and its drug release property / 生物医学工程学杂志

Hydroxyethyl chitin (HECH) is a water soluble chitin derivative made by etherification of chitin, ethylene chlorohydrin was used as etherification reagent in this reaction. A novel interpenetrating polymer network (IPN) composed of HECH/PAA was prepared. The IR spectra confirmed that HECH/PAA was formed through chemical bond interaction. The sensitivity of this hydrogel to temperature and pH was studied. The swelling ratio of this hydrogel in artificial intestinal juice is much greater than that in artificial gastric juice. The IPN hydrogel exhibited a typical pH-sensitivity, and its degree of swelling ratio increased with the increase of temperature. The sustained-release drug system of Dichlofenac potassium was prepared by using HECH/PAA as the drug carrier. The release experiment showed a perfect release behavior in artificial intestinal juice. This IPN is expected to be used as a good drug delivery system of enteric medicine.