Study On The Mechanism Of Reaction Between Amino Acid And Silver(Ⅰ)ion And Preparation Of Amino Acid-silver Nanoparticles

Metal ions play an important role in life science, many aspects of life processes are unable to separate from the interaction of metal ions with biomolecules. Such as: biological utilization; ingestion and transportation of metal ions; benefic and toxic effects of metal ions; the stable function on metals and protein structures; metal ions of combination in biological active center; bioelectron transmittance; cell toxicity, chemical treatment and organization of selectivity about distribution of metal medicaments etc, so studies on the reaction of metal ions and biomolecules are hotspot for scientific research. Many aspects involve the reaction between amino acid and silver( I ) ion, but there are still some questionable points about their mechanism explanation. For this reason, the mechanism of interaction between silver( I) ion and 4 α-amino acids such as tryptophan, histidine, methionine and leucine has been further investigated at the molecular level as well as preparation of amino acid-silver( I) solid particles in the micro emulsion.It is the major part to study the effects of pH medium, amino acid concentration, silver( I ) ion concentration, SDS, tris, HCHO, lightness intensity, lightness time and temperature on the reaction between amino acid and silver( I ) ion. The UV-Vis spectra results indicated: Comparing with amino acid, amino acid-silver( I ) system has maximum absorbance at Soret-band and its absorbance peak has almost moved to lower frequency, it showed the new species was formed and the colour of solution was changed from colourless, orange-red to blown-red. With generation of new complexe, amino acid residues retaining the reductive property of Ag~+ to Ag~0, so it appeared wide and smooth absorbance at 400nm~500nm. This phenomenon belongs to static fluorescence quenching. Many transition metal ion are coordinate with oxygen atoms of α-carboxyl group and nitrogen atoms of α-amino-group, with silver( I ) ion formated four-coordination. But tryptophan, methionine, histidine respectively contain indole, sulfur-aether and imidazole, with silver( I) ion formated six-coordination. The results showed the optimum condition for the interaction between amino acid and silver( I ) ion, and found that the reaction belong to lightness-assistance reaction.The dissociation constants of amino acids, stability constants of amino acid-silver( I ) coordination complexes, electrokinetic potential of amino acid-silver( I ) system are calculated by pH electromeric titration, electrophoresis methods respectively. The results showed leucine-silver( I ) system, methionine-silver( I) system, histidine-silver( I) system and tryptophan-silver( I) system are carried on negative charge and move to positive polar.Amino acid-silver( I) solid particles were prepared in the micro emulsion, its appearance and structure were characterized by means of IR spectra, XRD spectra and TEM..