Glucosamine-carrying temperature- and pH-sensitive microgels: preparation, characterization, and in vitro drug release studies.

Glucosamine-carrying temperature- and pH-sensitive microgels with an average diameter of about 100 nm were successfully prepared by free radical precipitation polymerization. The thermo- and pH-responsive properties of the microgels were designed by the incorporation of N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) to copolymerize with acrylamido-2-deoxyglucose (AADG). The stimuli sensitivity of the microgels was studied by the measurement of their sizes and volume phase transition temperature (VPTT) under different surrounding conditions. The results showed that the microgels were responsive to temperature, pH, and ionic strength, and could have a desired VPTT by modifying AADG and AAc contents. The effect of temperature and pH on insulin release from the microgels was also investigated. The release of drug at the tumor-surrounding environment is faster than that under normal physiological conditions. A preliminary in vitro cell study showed that the glucosamine-carrying microgels are more biocompatible to mouse fibroblast cells, compared to the microgels without glucosamine. These glucosamine-carrying dual-sensitive microgels may be promising carriers for targeted drug delivery to tumors.