Biomolecule- Gold Cluster Hybrid Materials Preparation And Their Environmental And Biomedical Applications

Hybrid materials are formed by at the nano or molecular levels minimum two different assembly modules. The hybrid materisl frequently show special functions based on a composite mechanism. Hybrid materials frequently contain both inorganic and organic materials.In living bodies, proteins and DNA are what we usually call the biopolymer, which are also good assembly units. For example, proteins are composed of twenty distinct natural amino acids and contain natural complex structures at nanoscales and are involved in chemical reactions. A number of researchs concern protein assembly: protein-protein assembly(e.g., antigen and antibody assembly and protein- protein recogniations), proteins- metal ions assembly(e.g., histidine- nickel ion complex formation and their applcations in designing line, ring, spiral structures, protein-zinc ions recognition and their application in nano-sheet formation), proteins-organic macromolecules assembly(e.g., assembly using a phenylalanine-glycine small peptide and cucurbituril, and protein and polymer hybrids via Cu-LPR radical mechanism.Gold nanoclusters are a special class of materials formed by several hundred gold atoms with the size of approximately one nanometer. Because of their small size, large surface area, these materials show surface, quantum size, volume, macroscopic quantum tunneling, and dielectric field effects. The gold nanoclusters are excellent fluorescent materials. Compared with the traditional fluorescent materials, these gold nanoclusters show several advantages. For example, small light emitting fluorescent organic molecules are short in luminous light emitting time suffer severe light bleaching and other shortcomings; the preparation process for quantum dots is complicated and accompanied by toxic polution. Traditional synthetic methods for gold nanocluster synthesis use polyamide- amine dendrimer or cetyl trimethyl amine and thiol group of small molecules as stabilizers, and sodium borohydride as a reducing agent. The biggest drawback of the traditional method lies in its complexcity and toxicity, and has a certain impact on the environment. In recent years, there have been some relatively friendly methods for the synthesis of gold clusters, such as the use of protein and DNA as template and/or reducing agents.We tried to use biocompatible polymeric materials for hybrid material designing, such as proteins and thiol containing small molecules as organic part, and precious metal as inorganic part. In the hybrid process, the gold clusters are formed at nanoscale with size around 1 nm to 5 nm. Especially biocompatible and environmentally friendly materials such as proteins are used for the gold nanocluster synthesis. These gold clusters show many important applications in environmental heavy metal detection, detection of biological samples, cell imaging, and drug transportation and other fields.Dithiothreitol(DTT) is a commonly used reducing agent. DTT served as both stabilizing and reducing agents for gold nanoclusters synthesis, which was carried out at room temperature and near neutral p H conditions. The synthesized materials were characterized by the UV absorption spectra, fluorescence spectra, X-ray photoelectron spectroscopy(XPS) and high-resolution transmission electron microscopy(TEM). It is found that the gold clusters have a sensitive response toward the copper ions. We use these hybrid materials for copper ion concentration determination of human serum, which is comparable to the commercial kit.Trans-2-enoyl- acyl carrier protein reductase(Fab I) is an enzyme involved in fatty acid synthesis pathway, which is also a genetic target for antibacterial drugs. Under mild conditions, we have synthesized Fab I-gold cluster hybrid materials. The material can be applied to a nylon membrane for mercury ion test strip preparation with good sensivity. We used the test paper to detect water quality in Changchun region.We next desgined self-assembly hybrid materials based on three modules: bovine serum albumin(BSA), tryptophan, and gold clusters. The hybrid materials were characterizatied through TEM, SEM and atomic force microscopy(AFM), indicating their interesting geometrical structures. These materials show distinct luminescent properties and can be a new class of cell-permeating agents for cell imaging and drug delivery related applications.We also tried to use BSA with glycine, histidine or other amino acid under different conditions of self-assembled hybrid materials synthesis. By screening we finally got some hybrid materials have different luminescent properties. We try to assemble process and mechanism of the hybrid material is discussed certain degree of research. At the same time, for the hybrid materials by prokaryotes and fungi of the supramolecular assembly packages as well as for cell multicolor imaging applications.