Fabrication of Gold Nanoparticle Microcapsules via Self-assembly of α-Synuclein and Their Application for Cargo Delivery System

Abstract

Bio-applicable cargo delivery system requires biocompatibility, in vivo stability, and controlled cargo release responding to external stimuli at target site. Here, the strategy for manufacturing Pickering emulsions of various nano-sized particles including gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), quantum dots (QDs) and magnetic nanoparticles (MNPs) by adjusting the surface property using self-assembly protein of α-synuclein (αS), and the αS-mediated fabrication of microcapsule as a cargo carrier derived from the Pickering emulsions were introduced. Both processes of the Pickering emulsion formation and the microcapsule fabrication are entirely due to the property of the αS conjugates onto nanoparticle. By encapsulating the nanoparticles with αS, the particles have a much higher detachment energy, which allows the particles to stably keep the Pickering emulsions structure from coalescence or degradation. As the organic solvent-induced β-sheet structures between the αS are formed, the emulsions could be derived into mechanically and chemically stable microcapsules. With Rhodamine 6G (R6G) loaded, the microcapsules exhibited controlled release of R6G by triggers such as proteases, pH and specific metal ion. Additionally, a rapid and localized heat generating photothermal activity of the microcapsules composed of AuNPs was investigated and the effectiveness of the hyperthermia therapy was confirmed by in vitro cell viability test. Furthermore, the microcapsules could obtain additional functions such as orthogonal cargo loading, imaging property, and targeting characteristic by taking inverted micelles, other nanoparticles, or antibodies, respectively. Taken together, fabrication of the AuNP microcapsule for cargo delivery system are suggested, and the resulting multi-functional microcapsules could be served as ideal cargo carriers that exhibit appropriate properties in the applications for their uses.