Facile Spray-Drying Assembly of Uniform Microencapsulates with Tunable Core–Shell Structures and Controlled Release Properties.

Microencapsulates with defined core–shell structures are of interest for applications, such as controlled release and encapsulation, because of the feasibility of fine-tuning individual functionalities of different parts. Here, we report a new approach for efficient and scalable production of such particles. Eudragit RS (a co-polymer of ethyl acrylate, methyl methacrylate, and a low content of methacrylic acid ester with quaternary ammonium groups) was used as the main shell component, with silica as the core component, formed upon a single-step spray-drying assembly. The method is capable of forming uniform core–shell particles from homogeneous precursors without the use of any organic solvents. Evaporation-induced self-assembly attained the phase separation among different components during drying, resulting in the core–shell spatial configuration, while precise control over particle uniformity was accomplished via a microfluidic jet spray dryer. Direct control over shell thickness can be achieved from the ratio of the core and shell ingredients in the precursors. A fluorescent compound, rhodamine B, is used as a highly water-soluble model component to investigate the controlled release properties of these microencapsulates, with the release behaviors shown to be significantly dependent upon their architectures. [ABSTRACT FROM AUTHOR]