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O. Akhavan,E. Ghaderi 한국물리학회 2009 Current Applied Physics Vol.9 No.6
Bactericidal activity of high concentration Ag nanoparticles immobilized on surface of an aqueous sol–gel silica thin film was investigated against Escherichia coli and Staphylococcus aureus bacteria. Size of the surface nanoparticles was estimated in the range of 35–80 nm by using atomic force microscopy. Due to accumulation of the silver nanoparticles at near the surface (at depth of 6 nm and about 40 times greater than the silver concentration in the sol), the synthesized Ag–SiO2 thin film (with area of 10 ㎟) presented strong antibacterial activities against E. coli and S. aureus bacteria with relative rate of reduction of the viable bacteria of 1.05 and 0.73 h-1 for initial concentration of about 105 cfu/ml, respectively. In addition, the dominant mechanism of silver release in long times was determined based on water diffusion in surface pores of the silica film, unlike the usual diffusion of water on the surface of silver-based bulk materials. Therefore, the Ag nanoparticles embedded near the surface of the SiO2 thin film can be utilized in various antibacterial applications with a strong and long life activity. Bactericidal activity of high concentration Ag nanoparticles immobilized on surface of an aqueous sol–gel silica thin film was investigated against Escherichia coli and Staphylococcus aureus bacteria. Size of the surface nanoparticles was estimated in the range of 35–80 nm by using atomic force microscopy. Due to accumulation of the silver nanoparticles at near the surface (at depth of 6 nm and about 40 times greater than the silver concentration in the sol), the synthesized Ag–SiO2 thin film (with area of 10 ㎟) presented strong antibacterial activities against E. coli and S. aureus bacteria with relative rate of reduction of the viable bacteria of 1.05 and 0.73 h-1 for initial concentration of about 105 cfu/ml, respectively. In addition, the dominant mechanism of silver release in long times was determined based on water diffusion in surface pores of the silica film, unlike the usual diffusion of water on the surface of silver-based bulk materials. Therefore, the Ag nanoparticles embedded near the surface of the SiO2 thin film can be utilized in various antibacterial applications with a strong and long life activity.
Bordbar, A.K.,Ghaderi, A.R.,Safaei, E.,Tangestaninejad, S.,Eslami, A.,Saboury, A.A.,Moosavi Movahedi, A.A. Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.5
In the present work, the interaction of three water soluble porphyrins, tetra(p-trimethyle) ammonium phenyl porphyrin iodide (TAPP) as a cationic porphyrin, tetra sodium meso-tetrakis (p-sulphonato phenyle) porphyrin (TSPP) as an anionic porphyrin and manganese tetrakis (p-sulphonato phenyl) porphinato acetate (MnTSPP) as a metal porphyrin, with histone H₂B have been studied by isothermal titration microcalorimetry at 8 mM phosphate buffer, pH 6.8 and 27 °C. The values of binding constant, entropy, enthalpy and Gibbs free energy changes for binding of the first MnTSPP, and first and second TSPP and TAPP molecules were estimated from microcalorimetric data analysis. The results represent that the process is both entropy and enthalpy driven and histone induces self-aggregation of the porphyrins. The results indicate that both columbic and hydrophobic interactions act as self-aggregation driving forces for the formation of aggregates around histone.