A Study of Protein and Peptide-directed Nanoparticle Synthesis for Catalytic Materials

Nanoparticles have received much attentions due to their unique properties that makes them suitable candidates for a broad range of applications. As the size of particles decreases, their surface area-to-volume ratio would increase which is the main cause of much attention. In addition to the size, their morphologies and compositions may also play important roles for defining unique properties. Nanoparticle synthesis include both bottom-up and top-down strategies. To control the process of inorganic nanoparticles synthesis one could follow the bottom-up approach to have atom-level control over their compositions, morphologies, phases, and sizes which is the subject of this work. Due to their specific sequence of amino acids, proteins and peptides has been demonstrated to be used for nanoparticle synthesis. The main obstacle to widespread development and commercialization of protein and peptide-directed nanoparticle synthesis platforms is their high cost when the peptide is obtained by traditional chemical synthesis. A promising approach for the cost-effective production of nanoparticles using protein/peptide derives from our effort to develop Escherichia coli into an expression platform. In contrast to most biochemical engineering applications, the purity of the fusion proteins and peptides may be less stringent for nanoparticle synthesis, demonstrating the fact that crude bacterial lysates containing fusion peptides may be used in lieu of expensive, pure peptide in nanoparticles synthesis while the nucleation and growth mechanism is consistent with traditional systems. Indeed, it is conceivable that simply concentrating the protein/peptide may be the only purification step necessary for nanoparticle synthesis. Additionally, catalytic activities of the fusion protein-directed nanoparticles were evaluated using the most popular and efficient routes for the formation of carbon– carbon bonds, Suzuki-Miyaura coupling and Stille coupling reactions. The unpurified fusion protein-directed nanoparticles showed slightly higher catalytic activity comparing to the chemically synthesized peptide counterparts. Moreover, fusion protein-directed nanoparticles presented high catalytic activities in green solvents as well as high stability and recyclability. They also could be utilized efficiently for the synthesis of Lapatinib precursor, an oral active anti breast cancer drug. The excel catalytic activity of the fusion protein-directed nanoparticles make them an excellent candidate for catalytic applications in the future