Polymer/Inorganic Nanoparticles:Synthesis,Characterization And Study For Their Antimicrobial Properties

Nanomaterials have attracted continous and remarkable interests in the past several years, because of their unique physical and chemical properties substantially different from bulk materials, as well as their great potential in the application of photonic, electronic, biomedicine, and catalysis. However, aggregation and precipitation of nanoparticles often limit their applications. To overcome this problem, nanoparticles are usually dispersed in an organic or polymer matrix.Infections that develop in surgical and traumatic wounds remain a disturbing problem nowadays. One key to minimize such a problem is the application of topical antibacterial agents. Silver has long been recognized as a highly effective and broad spectrum antimicrobial agent for the treatment of infectious wounds. It is generally stated that silver is the ideal antibiotic since it displays low cytotoxicity to mammalian cells and has broad range antibacterial activity against both Gram negative and Gram positive bacteria, so silver has emerged as an often-used element in the antibacterial field in recent years. In this dissertation, silver and silver bromide nanoparticles were studied. The study found that the smaller size of nanoparticles, the stronger its antimicrobial activity. The main contents are as follows.1. Preparation of Water-soluble Inorganic NanoparticlesMany metals are known to react easily with a number of nitrogen-containing or oxygen-containing organic compounds, such as amines, imines, pyridine and carboxylic acid. We have synthesized a polymer containing pyridyl and carboxyl groups and get gold nanoparicles, silver nanoparticles and silver bromide nanoparticles through reduction in situ or reaction with appropriate anions. Many examples of homogeneous systems use toluene as solvent. However, if these reactions could be performed in water, they would be considerably safer, cheaper, and more environmentally friendly. In this paper, we report on a random copolymer of poly[(4-vinylpyridine)-co-(acrylate acid)][P(4VP-co-AA)] resulted from the hydrolysis of poly[(4-vinylpyridine)-co-(tert-butyl acrylate)][P(4VP-co-tBA)]. The polymer is water soluble in a larger pH range and is used as a particle stabilizer for gold, silver and silver bromide nanoparticles. The intermediate and final products were characterized by gel permeation chromatography (GPC),1H NMR, transmission electron microscopy (TEM), UV-vis spectrophotometer, and X-ray diffraction (XRD). 2. Antibacterial Properties of Silver Nanoparticles and Silver Bromide NanoparticlesIn this dissertation, antimicrobial activity studies were carried out on both Gram negative (E. coli) and Gram positive (S. aureus) bacterial strains. The antibacterial properties of silver and silver bromide nanoparticles were obtained through the test of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The smaller size of nanoparticles, the stronger its antimicrobial activity. The antibacterial property of silver bromide nanoparticles is stronger than silver nanoparticles. This is due to Ag+is more easily released from silver bromide.