The Preparation,Characterization Of High-valence Silver Complexes And Research Of Their Antibacterial Activity

Silver antibacterial materials have been widely applied in fileds of commodity,filage and medicine because of their efficient,non-toxic and low drug resistance properties.However,high-valence silver antibacterial materials,which have the advantages of better antibacterial performance,resistance the interference of chloridion and well photostability,are being focused and becoming very potential antibacterial materials.High-valence silver oxides are the most widely applied among the high-valence antibacterial materials,but they can easily react with substrate materials of medicine.Especially the Ag2O3,it is very unstable to store.Synthesized high-valence silver complexes antibacterial materials that have been reported also exist the problem of poor stability.Base on the analysis above,we have synthesized several high-valence silver complexes,and the antibacterial ability for Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)was studied.There were no related literature reports yet.Specific contents are as fellows:(1)Fairly Stable divalent silver complexes: bis(pyridine)bis(dinitrogen)Silver(II)Hydroxide([Ag(py)2(N2)2](OH)2)and tris(2-aminopyridine)hydroxosilver(II)hydrogensulfate monohydrate([Ag(2-Apy)3(OH)](HSO4)·H2O)have been synthesized with pyridine and 2-aminopyridine as ligands.The products were characterized by Fourier Transform Infrared Spectroscopy(FT-IR),elemental analysis and X-ray Photoelectron Spectroscopy(XPS).The growth-inhibitory curves and the Minimal Inhibitory Concentration(MIC)were applied to evaluate the antibacterial ability of complexes.The results show that the two complexes begin to obviously inhabit the growth of test bacterias at very low concentration of 0.5 μg/mL,the MIC of two complexes for E.coli both are 5 μg/mL,MIC for S.aureus both are 20 μg/mL.Photostability test indicates the two complexes both have excellent photostability.(2)Ethylene-dibiguanide hydrogensulfate([En(BigH2)2](HSO4)2·5H2O)was synthesized with template method,and it’s trivalent silver complex was futher synthesized.The ligand and complex were characterized by 1H-Nuclear Magnetic Resonance(1HNMR),FT-IR,elemental analysis and XPS.The dibiguanide trivalent silver complex can inhabit the growth of E.coli and S.aureus at concentration of 0.5 μg/mL,but Ethylene-dibiguanide hydrosulfate don’t have any inhibitory effect even at 800 μg/mL.MIC of trivalent silver complex for two bacterias are 10 μg/mL and 40 μg/mL respectively,and it have the well photostability,too.Besides,we have preliminarily studied the antibacterial mechanism of two divalent silver complexes and trivalent silver complex.According to the experimental results,we speculated: oxidation and reduction reactions take place in antibacterial process of high-valence silver complexes,and produce free radical.(3)We synthesized water-soluble anion porphyrins Tetrakis-(4-sulfophenyl)porphyrin(Na4TPPS)and cation porphyrin Tetrakis-(4-N,N,N-trimethylaminophenyl)porphyrin(TAPP),and their divalent and trivalent silver complexes were futher synthesized.The porphyrins and complexes were characterized by 1HNMR,Ultraviolet spectrum,FT-IR,elemental analysis and XPS.The inhibition zone,MIC and Minimal Bactericidal Concentration(MBC)were applied to detect the photo-toxicity and dark toxicity of complexes.The results indicate cation porphyrin and it’s high-valence silver complexes have better antibacterial ability than anion porphyrin and it’s high-valence silver complexes.This result is related to superficial tissue of bacteria.Trivalent silver porphyrin has the stronger dark toxicity than divalent silver porphyrin and free porphyrin,the free porphyrin and trivalent silver porphyrin have stronger photo-toxicity.Ultraviolet spectrum suggests that trivalent silver porphyrin can produce the free radical and other active compounds in the dark,and the yield is bigger in the presence of the light.