Release profile characteristics of biodegradable-polymer-coated drug particles fabricated by dual-capillary...

This study describes one-step synthesis of coated particles by a dual-capillary electrospray (ES) system to produce monodisperse PLGA-coated drug particles. Different from a single-capillary ES system, the dual-capillary ES system separates drug and coating material, i.e., PLGA, solutions in two separate flow channels formed by two co-axially aligned capillaries and produce particles with the core(drug)-shell(PLGA) structure. No emulsion process is involved in the ES process. Our study shows that the studies system can achieve nearly 100% drug encapsulation efficiency with the proper system setting. Through the variation of PLGA concentration and the electrical conductivity of spray solutions, monodisperse PLGA-coated drug particles with sizes ranging from 165nm to 1.2microm were prepared. The drug release rates of prepared particles show that the small particles released the drug more rapidly than large ones. The SEM images of different release timing also show that the penetration of water into particles increases with the decrease of particle size, resulting in the fast particle swelling and eventually rupturing. This result demonstrates that the drug release profile can be controlled by tuning the particle size. We also observed two unique characteristics from the release behavior of drug-loaded PLGA particles produced by the dual-capillary ES system. One is that PLGA particles with the sizes smaller than 1microm in diameter rupture before they were degraded and the drug release profile is therefore dominated by the penetration of water and drug diffusion. The other characteristic is that the core-shell structure of drug-loaded PLGA particles minimizes the initial burst release of drug. It is because the drug is fully encapsulated in the core of particles (without the surface drug loading).