Preparation of a novel alginate hydrogel microspheres covered by hollow silica for controlled-release application

Sodium alginate hydrogel has been widely used in the field of controlled-release. In this paper, in order to prevent the negative effect of fast degradation and explosive release of pure sodium alginate hydrogel in the drug delivery process, we developed a novel alginate hydrogel supported by hollow silica microsphere for drug delivery. Briefly, the drugs were fused with sodium alginate and the hollow silica microspheres followed by ion crosslinking to form a composite hydrogel microsphere with a core–shell structure (SA@SiO2). The structure and morphology of the composite hydrogel were characterized by Fourier infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), scanning electron microscope (SEM), transmission electron microscope (TEM) along with fluorescence microscope. On this basis, using three different types of organic compounds (rhodamine B, Indocyanine green and salicylic acid) as model molecules, the controlled-release performance of the SA@SiO2 microspheres were investigated in detail. The research results show that the drug delivery system has broad-spectrum controlled-release performance for different types of molecules, and the controlled-release time can exceed 40 h. At the same time, the pH- responsive property of the sodium alginate hydrogel endows the delivery system with a certain targeting function. This study provides a new strategy for constructing an efficient targeted drug controlled-release system.