Nanoporous multilayer poly(l-glutamic acid)/chitosan microcapsules for drug delivery

Nanoporous poly(l-glutamic acid)/chitosan (PLGA/CS) multilayer microcapsules were fabricated by layer-by-layer (LbL) assembly using the porous silica particles as sacrificial templates. The LbL assembled nanoporous PLGA/CS microcapsules were characterized by Zeta-potential analyzer, FTIR, TGA, SEM, TEM and CLSM. 5-Fluorouracil (5-FU) was chosen as model drug. The drug loading content of PLGA/CS microcapsules depends on loading time, loading temperature, pH value and NaCl concentration. High loading capacity of microcapsules can be achieved by simply adjusting pH value and salt concentration. Moreover, 5-Fu loaded microcapsules take on a sustained release behavior, especially in an acid solution, in contrast to burst release of bare 5-Fu. The kinetics of 5-Fu release from PLGA/CS microcapsules conforms to Korsmeyer-Peppas and Baker-Lonsdale models, the mechanism of which can be ascribed to priority of drug diffusion and subordination of polymer degradation. The MTT cytotoxicity assay in vitro reveals the satisfactory anticancer activity of the drug-loaded PLGA/CS microcapsules. Therefore, the novel nanoporous PLGA/CS microcapsules is expected to find application in drug delivery systems.