Drug Release Behaviors Of A Thermo-Sensitive Poly(N-acryloylglycinates) Hydrogel

Intelligent hydrogels refer to a reversible response to external stimuli such as pH, temperature, ionic strength, electric field, magnetic and so on. Because of the unique property of intelligent hydrogel, there are have a wide range of applications in chemical valve, molecular devices, enzyme and cell immobillzation and controlled drug release and other areas. The main contents for the chapter is the synthesis, characterization and drug release behaviors of a pH or temperature sensitive poly(N-acryloylglycinates) hydrogel. The main contents in the thesis are listed as follow:A pH/temperature and degradable responsive hydrogel (PSMEA) was prepared from chitosan (CS), N-acryloylglycine methyl ester (AGM), N-acryloylglycine ethyl ester (AGE), acrylic acid (AA) and N-methylenebisacrylamide (NMBA). The swelling properties of PSMEA were systematically investigated at different temperature, pH and CS content. It was found that the PSMEA demonstrated obvious pH and temperature responsive nature. The cumulative drug release hydrogel increased with the rise of temperature, increased significantly with the rise of pH value, which shows the sensitive pH and temperature-controlled release.As a drug delivery carrier, a novel pH/temperature sensitive bead (pTSB) with core-shelled structure from poly(N-acryloylglycine) (PAG), copoly(N-acryloylglycine methyl este and N-acryloylglycine ethyl ester) was prepared by two steps. In pH=7.4 phosphate buffer solution (PBS), the cumulative release amount of indomethacin loaded in the pTSB was about 60.1 % within 500 mins, but this value only reached to 22.3 % in pH=2.1 PBS. The release behaviors of indomethacin from pTSB also exhibited a remarkable dependence on PAG content in the core. Additionally, the release rate of indomethacin was much faster at 18 oC than that at 37 oC due to the temperature sensitivity of poly(N-acryloylglycinates).A novel pH/thermo-responsive hydrogel with porous structure (HME), as a drug carrier, was prepared from N-acryloylglycine methyl ester (AGM), N-acryloylglycine ethyl ester (AGE) and sodium alginate (SA). In this system, CaCO₃ powder and N, N-methylenebisacrylamide (NMBA) were used as a pore-forming agent and crosslinking agent, respectively. The porous HME was characterized by differential scanning calorimetry (DSC), cold field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and surface area and porosity analysis. It was found that the HME demonstrated obvious pH and temperature responsive nature. The cumulative drug release hydrogel increased with the rise of temperature, increased significantly with the rise of pH value, which shows the sensitive pH value and temperature control release...