Chitosan oligosaccharide coated mesoporous silica nanoparticles for pH-stimuli responsive drug delivery applications

Biopolymer-coated drug delivery system with high drug-loading efficiency and pH-stimuli responsive drug release to the target site receives much research interest in cancer therapy. In this study, we have synthesized a marine biopolymer, namely chitosan oligosaccharide (COS) coated mesoporous silica nanoparticle (MSNs@COS NPs) system for pH-responsive drug delivery applications. The COS coating onto the silica nanoparticles was performed through metal-ligand complex coordination approaches. The prepared MSNs@COS NPs system were characterized by low-angle X-ray diffraction (XRD), Fourier-transform infrared (FTIR), N-2 adsorption-desorption and transmission electron microscopic (TEM), and thermogravimetric analyses. The COS-coated MSNs@COS NPs system shows high drug-loading capacity, good drug retention efficiency under physiological pH (pH 7.4) conditions, and an intracellular pH-responsive drug release behavior under acidic pH (pH 6.5, 5.0, and 4.0) environments. Furthermore, the biocompatibility and the intracellular uptake behavior of the MSNs@COS NPs system were evaluated by using MDA-MB-231 cells. The in vitro cytotoxicity and fluorescence microscopic analysis results evidenced that the synthesized MSNs@COS NPs system is biocompatible and could be readily taken up by MDA-MB-231 cells. Therefore, we believe that the proposed system could be applicable for pH-stimuli responsive controlled drug delivery applications in cancer therapy.