▎ 摘　　要

The ability to integrate both high encapsulation efficiency and controlled release in a drug delivery system (DDS) is a highly sought solution to cure major diseases. However, creation of such a system is challenging. This study was aimed at constructing a new delivery system based on thermoresponsive poly(N-isopropylacrylamide- co-styrene) (PNIPAAm-co-PS) hollow microspheres prepared via two-step precipitation polymerization. To control the diffusion-driven drug release, the PNIPAAm-co-PS spheres were electrostatically coated with graphene oxide (GO) nanosheets. As a result of the coating the permeability of the copolymer-GO hybrid microspheres was reduced to an extent that suppressed the initial burst release and enabled sustained drug release in in vitro testing. The hybrid microspheres showed improved drug encapsulation by 46.4% which was attributed to the diffusion barrier properties and p-conjugated structure of GO. The system presented here is promising to advance, e.g., anticancer drug delivery technologies by enabling sustained drug release and thus minimizing local and systemic side effects.