Programmable Self-assembly Study Of PLLA/Polypeptide Based On AuNPs

Self-assembly is one of the most important technologies to form new materials andgenerate novel functions, which run through chemistry, physics, materials science andbioscience. In recent years, due to good biocompatibility and multifunctionality,self-assemblies based on gold nanoparticles (AuNPs), biomacromolecule and artificialbiodegradable materials have been applied widely in drug delivery, tumor imaging and tissueengineering scaffold areas. However, up to now, there are still many drawbacks in the size-and morphology-controlled assembly of above-mentioned materials, which restricts theirpractical application and development in biological medicine field. Based on the solvophobicinteraction among poly(L-lactide)(PLLA) molecules and coordination between metal ionsand polypeptides, this thesis mainly focused on the programmable self-assembly ofAuNPs-based PLLA or polypeptide. On one hand, the programmable self-assembly of PLLAwas performed by varying the chain length of PLLA, amounts of PLLA modified on AuNPsand assembly unit etc. concentrations. On the other hand, the fluorescence intensity ofsynthesized gold nanoclusters (AuNCs) was regulated controllably by changing metal ionsand pH value. Major results of this thesis are as follows:1. Star-shaped AuNPs-PLLA polymer was synthesized and programmableself-assembled through solvophobic interaction. Short-chain PLLA at high concentrationtended to assemble into hollow spheres while long-chain PLLA did not. Along with thedecrease of concentration (2%â†'1%, wt/v), the morphology of high density AuNPs-PLLAself-assemblies (sa-AuNPs-PLLA) changed from spheres to porous bulks. Thinner andsmaller assemblies with uniform distributed porous were obtained, along with the decrease ofdensity and concentration ofAuNPs-PLLA.2. In vitro cells viability and immunofluorescence assay demonstrated goodbiocompatibility and podocyte-targeted abilities of sa-AuNPs-PLLA. It showed nocytotoxicity even proliferative effect to podocyte--one of the kidney cells. Moreover, after thelinkage of anti-nephrin, sa-AuNPs-PLLA exhibited specific targeting ability. Combined withtheir structural features, sa-AuNPs-PLLA exhibit promising value on renal repairing.3. Fluorescent gold nanocluster modified with GSH (ABG) was synthesized, and itsfluorescence intensity was controllable tuned by the addition of metal ions and varying pHvalue. Transition metal ions (Co2+, Zn2+and Cd3+) induced ABG assemblies respondedobviously to pH value: fluorescence intensity in weakly acidic condition (pH=6.4) wasstrongly higher than that in neutral condition (pH=7.4), which is perhaps a promising probe for passive tumor image.