Preparation On Chitosan Coated Lysozyme-plga Cationic Nanospheres

Poly(lactide-co-glycolide) microparticles (MPs) and nanoparticles (PLGA NPs) have been extensively studied as drug carriers based upon the properties of degradability and biocompatibility. However, the lack of functional groups on the surface of PLGA NPs for covalent modification has limited the potential for surface tethering bioactive molecules including DNA, ligands or vaccines. Thus, various attempts for physical surface modification of PLGA NPs have been made by coating PLGA with surfactants or polymers. As such, cationic surface modification based upon the electrostatic interaction with the negatively charged surface of PLGA has been suggested as a potential method to modify the surface of PLGA NPs. It has been reported that chitosan(CHS) has preferable properties for improving drug absorption, such as protection of the drug against enzymatic degradation and absorption-enhancing effects. We chose CHS to modified the surface of PLGA-NPs because of the cationic, biodegradable, and bioadhesively.Biodegradable poly(D,L-lactic-co-glycolic acid)(PLGA) was subject to an activation via DCC followed by chemical bonding to lysozyme,where a terminal carboxylic acid in PLGA was coupled with primary amine groups present in lysozyme, and the compound thereby was directly incorporated into nanospheres by an oil-in-water(OAV) single emulsion solvent evaporation method with its cationic surface modified by chitosan(CHS). Particularly, the method was optimized at various conditions. The results showed that the diameter of the nanospheres can be controlled within a range of 450±50nm, and theζpotential of the nanospheres can be as high as 42.5mV when pH was 4.2The optimized conditions were as follows: p(CHS) equals to 3 mg/mL,ρ(PLGA) equals to 5mg/mL, and a content ratio of lysozyme to PLGA is 0.2/1. The nanospheres obtained at the optimized method showed a loading efficiency and encapsulation efficiency of 14.7% and 87.8% respectively, while the encapsulation efficiency is only 41.0% for nanospheres prepared at other conditions and the same condition by a W/O/W,method. SEM micrograph displayed that the morphology was round with regular shape when Lysozyme-PLGA nanospheres was modified with CHS. The release results displayed a sustained release rate of 70% after 20 days of release and a regular sustained release curve as compared with the release rate of 90% after 10 days for nanospheres prepared by prior W/O/W methods, which demonstrated a higher sustained release property than prior study.