Protein-controlled Synthesis Of Core-shell Nanoparticles And Their Functionalization

Core-shell nanoparticle(NP) is an excellent kind of functional material that consists of a functional core, easily-modified shell and the surface functional groups. The properties of core-shell NP can be modified for a variety of applications by controlling their synthesis processes. For biomedical applications, the materials for the shell should be stable, biocompatible, and easy to be modified. The core could be fluorescent dyes, quantum dots or fluorescent proteins.In this paper, we have investigated the synthesis and surface functionalization of protein-based core-shell NP, especially chitosan NP(P@CS-PEG-FA) and its application of bio-imaging and targeting. We also developed a novel solid-phase synthesis method for core-shell silica NPs. In addition, the interaction between silica NPs and proteins has been studied.(1) To achieve targeting capability for previously prepared core-shell chitosan si RNA vector, we functionalized PEG-FA on the surface of the NPs to improve its water solubility and enhance the targeting function. TEM, DLS and 1H NMR were used to characterize the morphology and composition of the NPs. The result of 1H NMR confirms that PEG-FA has been functionalized on the surface of NPs successfully. The result of TEM and DLS show that the prepared nanoparticles have well dispersibility, uniform particle size(16-18nm), enough positive charge. Cellular experiments show the PEG-FA-functionalized chitosan NPs have substantial targeting effect to FA-receptor rich cancer cells. And CCK-8 experiments show that the nanoparticles have no cytotoxicity.(2) We developed a new solid phase method to synthesize and functionalize core-shell silica NPs. The core of the NP is kept bound on the surface of resin beads during the whole synthesis and functionalization processes, making all the separation/purification of NPs and its precursors as simple as a few minutes of draining and washing the column. Each obtained silica NP has an eccentric core-shell structure with a single His-tag sticking out of the particle, which could be used for recycling or further addressable functionalization. The result of TEM shows that, the synthesized silica nanoparticle has a narrow size distribution, and HRTEM confirms the eccentric structure of silica NP.(3) Using FITC and TRITC, a pair of FRET dyes, to label the NP and proteins, we studied the interaction silica NPs and different proteins by FRET. Our primary results show that the interaction between NPs and proteins is a very fast dynamic process.