Synthesis and Characterization of biodegradable Poly (Vinyl caprolactam) grafted on to sodium alginate and its microgels for controlled release studies of an anticancer drug.

Biodegradable sodium alginate-g-poly (vinyl caprolactam) synthesized by graft copolymerization of N-vinyl caprolactam (VCL) on to sodium alginate (NaAlg) via free radical initiation mechanism using a redox initiation system. Grafting (%), efficiency (%), and conversion (%) were all found to depend on the content of potassium persulfate (KPS), VCL reaction temperature and time. The maximum % of grafting was ascertained to be 251 at the optimum conditions of 65 oC reaction temperature, 180 min of reaction time, 1.1098X10-3 mol of KPS and 7.1844X10-3 mol of VCL. Evidence of graft copolymerization was obtained by fouriertransform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Further, graft copolymer was used for preparation of microgels (MGs) using Ca+2 as a crosslinking agent. SEM results showed that the MGs are spherical in structure with smooth surface. The effects of pH and temperature on the swelling behaviour of MGs were studied and ascertained that they were sensitive to both pH and temperature. 5-FU drug was successfully loaded in to these MGs and encapsulation efficiency was found 84%. The release of 5-FU was systematically investigated as a function of temperature, pH, amount of crosslinker and % of drug loading concentration. The results indicate that the responsive MGs have the potential to be used as an effective pH and temperature controlled delivery of 5-FU for more than 12 h.

Pulsed release behavior of microgels coated layer-by-layer by polyelectrolyte in vivo and in vitro / 第二军医大学学报

Objective To Investigate the in vitro and in vivo release of chitosan-alginate microgels coated layer-by-layer by polyelectrolyte self-assembly. Methods The cores of the microgels were made by gelatinization using electrostatic microencapsulated and coated by polyelectrolytes using electrostatic attraction. The effects of different layers and ratios of polymer on the in vitro lease of FITC-dextran were evaluated. Histrological examination was carried out to observe the in vivo release process by injecting the coated microgels into mice. Results The results showed that alginate and calcium chloride concentrations and polyelectrolyte layers markedly affected the lag time of pulsed release and the relasing speed after lagging. Conclusion The release of microgels coated layer-by-layer by polyllectrolyte can be controlled in vitro and can be observed in vivo; meanwhile, the microgels are safe and have good biocompatibility.

Preparation of polyelectrolyte layer-by-layer coated microgels for pulsed drug delivery / 第二军医大学学报

Objective To Investigate the preparation method, the release profile and structure of the polyelectrolyte layer- by-layer coated chitosan-alginate microgels. Methods The cores of the microgels were prepared by a high voltage electrostatic system, and the semipermeable membrane outside the microgel was polyelectrolyte deposits on the core surface through electrostatic attraction. The influences of different ratios of materials on the expansion property and the in vitro cumulative release of the coated microgels were evaluated by a single factor experiment. Results The prepared polyelectrolyte-coated microgels were well-shaped, with a narrow range of diameter distribution. The lag time of in vitro release was 2. 67 h; the release was rapid after lagging, with the cumulative in vitro release being 72% within 3 h. Conclusion Polyelectrolyte layer-by- layer coated chitosan-alginate microgels can release payload in a pulsed fashion in vitro.