Controlled Synthesis And Properties Of Noble Nanomaterials Based-on Lysozyme Fibrils

Nanostructure materials have received steadily growing interests as a result of their excellent special properties and various applications in electrons, photonics, optoelectronics, catalysts and biomedicine. Controlled synthesis of nanostructures templated by amyloid fibrils is a new method emerging in recent years. The Amoyloid and amyloid-like fibrils, which is into highly ordered linear aggregates by the self-assembly of peptides and proteins, is a hot field receiving increasing attention because of the potential of these structures to construct artificial protein scaffolds for biomaterials applicati ons and its biological roles in health and disease. In this paper, we selected hen egg white lysozyme(HEWL), one kind of cheaper and easily obtained amyloid protein, to conduct a systematic study of the physical and chemical environment in which its fibrosis needed. Then, on this basis, design and shape it into a specific morphology of fiber bio-template and control the growth and assembly of platinum, palladium and gold noble metal nanomaterials under a mild and controllable condition. Finally, we’ve examined the electro-catalytic and fluorescence properties of these nanomaterials which used as catalysts for the fuel cell and materials for the fluorescent device. The details and results are summarized as follows:(1) The fibrosis factors of HEWL proteins were systematically investigated, including p H, substrate concentration, ionic strength of the solution, heating incubation time, and the external force, etc. Thus, by reasonable regulation and control of these factors, the fibrosis time of HEWL was successfully shorted from weeks into three days. This greatly reduced the time cost. Furthermore, using the rotary heating method, the fibrills prepared were only about 3.5 nm in diameter with about 4 microns long and arranged in array.(2) Pt nanosphere chains, Pt nanoparticle chains and directional Pt nanowires array were prepared respectively in the presence of HEWL fibrils which were obtained under different incubation period. Experiments showed that the different maturity HEWL fibrils had a great influence on the morphology of the samples. At the same time, we found that the synthesis of Pt nanocrystals was closely related to the fibril solution viscosity, co-incubation time, the types of reductant, and the operation of the reduction process. Last, the reaction kettle method was used to provide a higher temperature and pressure to improve the crystallization of Pt nanocrystals.(3) Nanospheres, nanoflowers, nanochains and nanowires of Pd were successfully synthesized. It was found that Pd salt precursors can promote the fibrosis process of HEWL proteins, which different from the preparation of Pt nanocrystals. That is, immature HEWL fibrils can be successfully used as template in self-assembly of Pd nanowires, instead of mature fibrils. In addition, the immature HEWL proteins showed a certain degree of weak reducing which can help with the reduction of the adsorbed Pd salt precursors on the fibrils. Finally, monodisperse Pd nanoparticles with uniform size and morphology were obtained using reaction kettle under higher temperature and pressure conditons.(4) A series of electrochemical tests of as-prepared Pt and Pd nanocrystals were conducted for the evaluation of electro-catalysis performance. Before all the test, samples were given a carbonizated treatment to help improve the electrical conductivity of HEWL fibrils, and the results showed that the electro-catalytic activities varied with the morphologies of the nanostructures. Hydrogen evolution experiment calculated that the ECSA value of c-HEWL-Pt is 65.02 m2/g, far higher than that of commercial JM Pt/C catalyst 37.5 m2/g. Methanol oxidation electrocatalysis found the c-HEWL-Pt is better than JM Pt/C in the first step of methanol oxidation, and has greater peak current density. Oxygen reduction test showed that the limit diffusion current density value of c-HEWL-Pt is 0.16 m A/cm2, higher than that of JM Pt/C 0.14 m A/cm2. The same electrochemical tests of c-HEWL-Pd also demonstrated that it has excellent electro-calalytic activity.(5) Controlled synthesis of Au nanochains and nanoparticle chains was studied with HEWL fibrils incubated under different incubation period. Experiments showed that the quantity of Au nanoparticles attaching to the HEWL fibrils could be increased by heating during the reduction process, instead of changing the molar ratio between salt precursors and fibrils. Optical performance test showed that the as-prepared Au nanoparticle chains was a kind of potential fluorescent material.