Preparation And Application Of Amino Acid Stable Gold / Silver Nanoclusters

Amino acids, the building blockds of proteins, have some active groups that can reduce the metal ions to metal nanoparticles and stabilize the as-prepared nanoparticles. Amino acids can form polymer matrix and special spatial structure under some conditions, which makes it possible to be template for preparation of nanomaterials. In this paper, we used amino acids as a reduced agent and stabilizing agent to syntheisize gold nanoclusters (Au NCs) with17atoms and silver nanoclusters (Ag NCs) with average size of1.24nm, and further investigated the properities of theses nanomaterials. This work mainly covered the following areas.1. Water-soluble Au NCs were synthesized by one-step method using histidine (His) as reductant and His and11-mercaptoundcanoic acid (MUA) as synergistic stabilizer. Au NCs were composed of17atoms determined by X-ray photoelectron spectroscope and Electrospray ionization mass spectrometry. Further analytical results showed that the specific composition of this Au NCs was AU17MUA4H22(AMH). AMH possessed many excellent properties, such as intense red fluorescence, long fluorescence lifetime, considerable stability, and good biocompatibility. Based on the excellent properties, cell imaging experiments were conducted in HeLa cell line using AMH as contrast agent. The rusults indicated that AMH exhibited good imaging performance.2. Under a rapid microwave-assisted approach, ultrasmall Ag NCs were synthesized through using Trp-GA, tryptophan (Trp) modified with glutaraldehyde (GA), as reduced agent. This method was simple, time-saving and no extra addition of other reduced agent and capping agent. The as-prepared Ag NCs exhibited intensen fluorescence, long fluorescent lifetime, high quatum yield and monodisperse Ag NCs. High resolution transmission electron microscopy (HRTEM) showed that the average size of the as-prepared Ag NCs was about1.24nm and the size distribution (1.2-1.5nm) of Ag NCs was95%. Moreover, the fluoresecent sensing system for mercury ions (Hg2+) was developed based on the specific response of Ag NCs to Hg2+. The sensing system exhibited the large detection regime (1pM-10mM) and the low detection of limit (0.658pM).