ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Pulsed drug delivery (PDD), which can be released at well-defined time points as the therapy needs, can decrease the frequency and avoid taking drug at night, thus improving patient compliance. Here we introduce three kinds of programmed PDD systems independent of external chemical triggering; they are divided according to the triggering mechanisms, degradation-triggered PDD, osmotic pressure-triggered PDD, and both degradationi and osmotic pressure-triggered PDD. This paper reviews preparing technique, release mechanisms and influencing factors of the three PDD systems. The release profiles of pulsatile PDD can be regulated for different therapeutic needs, requiring no external triggers; especially that the PDD system triggered by both degradation and osmotic pressure has a bright future.