Preparation Of Core-shell Nanoparticles By Biopolysaccharides And Their PH-sensitive Drug Release

Recently, controlled release nanosystems based on a wide range of biopolysac-charides materials, capable of selectively releasing cargo, that is, anticancer drugs and labeling dyes, under different external stimuli, have demonstrated their viability for use in a variety of biological applications. In this work, bilayers of chitosan (Cs) and phosphorylated polyvinyl alcohol (PPVA) were sequentially deposited on 3-aminopropyltriethoxysilane modified SiO2 nanoparticles via layer-by-layer electro-static self-assembly. The good spherical shape and size distribution were observed by DLS and TEM analysis.7-Hydroxycoumarin (7-HC) and rhodamine (RhB) as model drugs were loaded in the core and shell of the nanoparticles seperately. Confocal La-ser Scanning Microscopy (CLSM) shows the core-shell structure of HC-SiO2(PPVA/Cs)n-RhB nanoparticles and the embedded location of 7-HC and RhB. The pH-sensitive release investigation of RhB indicates that the release profiles of RhB from HC-SiO2(PPVA/Cs)3PPVA-RhB core-shell nanoparticles are totally dif-ferent at pH of 2.0,7.4 and 9.2. These results predict that the multifunctional nanopar-ticle SiO2(PPVA/Cs)n has a great potential for drug delivery.In addition, A new core-shell nanostructure consisting of inorganic hydroxyap-atite (HAp) nanoparticles as the core and organic pectin or carrageenan as the shell (denoted as HAp@pectin, HAp@Car) was successfully synthesized by a pre-gel method. By adjusting the molar ratio of calcium and phosphate we can regulation of growth morphology of HAp. Then an optimal spherical proportional was obtained, we further confirmed the spherical morphology through transmission electron microscopy (TEM) observation. Through the subsequent layer by layer technique, we successfully obtained the hybrid functional core-shell nanoparticles and applied them to pH re-sponsive drug delivery systems (DDS). The core-shell nanoparticles have the ad-vantages of hydroxyapatite and pectin, carrageenan, as the inorganic core, hydroxyap-atite provides pH responsive degradability, at the same time, the organic shell of pec-tin and carrageenan provides excellent biocompatibility, while, pectin exhibit a hepa-toma cell targeting better than carrageenan. Rhodamine 6G (R6G), a positively charged dye, which was chosed as a model drug for pH-sensitive DDS was encapsu- lated in the core-shell nanoparticles during synthesis. A comparative analysis about drug release behavior in vitro at different pH (2.0,4.5,7.4) values was carried out. The results indicated that more R6G molecules were released at lower pH conditions. This behavior is attributed to the pH-sensitive dissolution of the HAp core in acidic conditions. Furthermore, the results of the MTT assay indicated that the HAp@pectin-LBL, HAp@pectin-LBL nanoparticles were successfully uptaken by liver cancer cells (HepG2) without apparent cytotoxicity. This work indicates that the hybrid core-shell NPs can serve as a potential drug nanovehicles in the futher drug delivery systems.