Fabrication of functional micro-/nano-particles from biodegradable polymers and their use in cosmetic and biomedical applications

Biodegradable polymeric particles have attracted vast attention in cosmetic and biomedical fields because of their biocompatibility, non-toxicity, and degradability in natural environments. In this study, emulsification processes have been developed to fabricate micro- and nanoparticles from various biodegradable polymers. The first system involves the fabrication of hollow nanoparticles from poly(lactic acid-co-glycidyl methacrylate), P(LA-co-GMA) by a one-step phase inversion emulsification (PIE). The influence of surfactant migration and evaporation rate plays an important role in hollow structure formation. Monodispersed hollow nanoparticles with good colloidal stability are obtained. These nanoparticles were applied as UV-shielding additives in cosmetic applications. The hollow nanoparticles showed high UVA&UVB shielding capability and low cytotoxicity. They also exhibited high stability under UV exposure but could be degraded by hydrolysis after use. In a separate system, thermoresponsive gating particles have been developed for controlled release applications via a double emulsion solvent evaporation technique. Porous biodegradable micro/nanoparticles were prepared using Eudragit RS100, in which poly(N-isopropylacrylamide) (PNIPAM) was employed as a gatekeeper. Types of initiator systems play a key role in the polymerization of NIPAM, which influences the morphology, encapsulation efficiency, and loading capacity of the materials. The temperature-sensitive particles possessed a swollen conformation to block the pores and prevent the diffusion of a model drug below the volume transition temperature (TVPT). In contrast, the crosslinked PNIPAM nanogels transformed to be hydrophobic and collapsed, allowing the gate open and release the encapsulated compound. These thermoresponsive particles remarkably showed a precise “on-off” switchable release mechanism which is easy to control drug delivery when triggered at the body temperature. The developed materials have a high potential for use as UV-shielding additives in cosmetic products and drug delivery materials in biomedical and pharmaceutical applications.