Fabrication and Application of Functional Polymer-Protein Coreshell Nanoparticles

The study of polymer-protein nanoparticles is of increasing interest due to their various potential applications in biosensing, imaging, bioseparations, gene and drug delivery, etc. Synthetic polymers can be tailored with different functional groups and properties, therefore, they can serve as platforms to impart proteins with additional features and assist proteins to better perform biological functions. In this dissertation work, we were mainly focusing on the preparation of polymer-protein core-shell nanoparticles by synthesizing new functional polymers and assembling them with proteins for different applications. In chapter 1, a pyridine grafted diblock copolymer P(CL-g-Py)-b-PCL was prepared through ROP and CuAAC reactions. Core-shell nanoparticles (CSNPs) from the selfassembly of this polymer and transferrin (Tf) were characterized by dynamic light scattering, transmission electron microscope and circular dichroism. As compared with CSNPs prepared from homopolymer P4VP and Tf, these particles exhibited narrower size distribution, improved particle stability, and higher loading capacity for anticancer drug doxorubicin (DOX). Additionally, the drug loaded Tf/P(CL-g-Py)-b-PCL CSNPs can effectively target MCF7 cancer cells via the binding of Tf to Tf receptors. In chapter 2, we created the cellulase library. Three cellulases CelAt, CelGc, and CelF were purified and assembled with pyridine grafted polymers to create cellulase anchored CSNPs. The prepared CSNPs were characterized. The enzymatic activity of the immobilized cellulases were compared with free enzymes. Contrary to our hypothesis, none of the single-enzyme or double-enzyme, or triple-enzyme assembly systems showed obvious elevated enzyme activity as compared to free enzyme. Based on the study in chapter 2, in chapter 3, we synthesized block copolymer PS-bPSMA through one-pot RAFT polymerization and modified the polymer with NTA groups. The self-assembly of the polymer in the presence of Ni2+ ions led to the formation of nanoparticles of about 20 nm in aqueous solution. The NTANi complexes located on the particle surface can capture 6× His-tagged proteins by strong affinity binding. The conjugated proteins are within close proximity. The catalytic activity of cellulases was elevated after being assembled with NTANi containing micelles due to the enhanced local concentration and synergy effect. In chapter 4, besides synthetic polymer, we are exploring virus bio-nanoparticles TMV as a novel carrier for the immobilization of proteins. TMV has highly ordered architecture and uniform shape. The coat proteins of TMV were modified with NTANi groups via sequential diazonium-coupling and CuAAC reaction. The modified VNPs can be utilized for constructing novel biomaterials through the specific interaction between NTANi complexes and polyhistidine. Our current work employed two fluorescent proteins, eGFP and mcherry, as model proteins to study the potential of TMV-NTANi for protein immobilization. It was shown that eGFP and mcherry can be immobilized separately or together on TMV surface. We believe that this method can be extended to other 6×histagged functional proteins