Layer-by-layer assembly of poly(L-glutamic acid)/chitosan microcapsules for high loading and sustained release of 5-fluorouracil.

Hollow polyelectrolyte microcapsules based on poly(l-glutamic acid) (PLGA) and chitosan (CS) with opposite charges were fabricated by layer-by-layer (LbL) assembly technique using melamine formaldehyde (MF) microparticles as sacrificial templates. The LbL assembly of polyelectrolytes and the resultant PLGA/CS microcapsules were characterized. A hydrophilic anticancer drug, 5-fluorouracil (5-FU), was chosen to investigate the loading and release properties of the microcapsules. The PLGA/CS microcapsules show high loading capacity of 5-FU under conditions of high drug concentration and salt adding. The high loading can be ascribed to spontaneous deposition of 5-FU induced by hydrogen bonding between 5-FU and PLGA/CS microcapsules. The PLGA/CS microcapsules show sustained release behavior. The release rate of 5-FU drastically slows down after loading in PLGA/CS microcapsules. The 5-FU release from PLGA/CS microcapsules can be best described using Ritger-Peppas or Baker-Londale models, indicating the diffusion mechanism of 5-FU release from the PLGA/CS microcapsules. In vitro cytotoxicity evaluation by the MTT assay shows good cell viability over the entire concentration range of PLGA/CS microcapsules. Therefore, the novel PLGA/CS microcapsules are expected to find application in drug delivery systems because of the properties of biodegradability, high loading, sustained release and cell compatibility.