SPR (Surface Plasmon Resonance) is an emerging optical biosensor which can monitor the processes at metal interface in real time without labeling requirements.Instrument SPR-2004 can sense two areas in one channel and...SPR (Surface Plasmon Resonance) is an emerging optical biosensor which can monitor the processes at metal interface in real time without labeling requirements.Instrument SPR-2004 can sense two areas in one channel and get two signals at same time in one test.One signal is the graph of the reaction;the other is the graph of reference.SPR biochip is modified with dextran,and only reaction area can be used to immobilize the protein.Two methods of antibody immobilization on chip were tested.One was to immobilize directly,the other was to immobilize protein A firstly and then the antibody was caught by immobilized protein A.The latter was chosen as suitable for retention of the native binding ability with virus of antibody.The latter chip was used to detect SARS-Cov.The signal of detection reached to 60 units within 40 min.It was 55 units even after reference.展开更多
Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as ...Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as well as dead cells revealed that both extracellular adsorption and intracellular accumulation were involved in the Pb2＋removal from the liquid phase. Of the sequestered Pb（II）, 8.5% was held by physical entrapment within the cell wall, 43.3% was held by ion-exchange, 9.7% was complexed with cell surface functional groups or precipitated on the cell surface, and 38.5% was intracellularly accumulated.Complexation of Pb2＋with carboxyl, hydroxyl, carbonyl, amido, and phosphate groups was demonstrated by Fourier transform infrared spectroscopic analysis. Precipitates of Pb5（PO4）3OH, Pb5（PO4）3Cl and Pb10（PO4）6（OH）2that formed on the cell surface during the biosorption process were identified by X-ray diffraction analysis. Transmission electron microscopy–energy dispersive spectroscopic analysis confirmed the presence of the Pb（II）precipitates and that Pb（II） could be sequestered both extracellularly and intracellularly.Incubation with B. subtilis DBM significantly decreased the amount of the weak-acid-soluble Pb fraction in a heavy-metal-contaminated soil, resulting in a reduction in Pb bioavailability, but increased the amount of its organic-matter-bound fraction by 71%. The ability of B.subtilis DBM to reduce the bioavailability of soil Pb makes it potentially useful for bacteria-assisted phytostabilization of multi-heavy-metal-contaminated soil.展开更多
基金This work was supported by the National Natural Science Foundation of China （No. 60341005 and No. 60427001）.
文摘SPR (Surface Plasmon Resonance) is an emerging optical biosensor which can monitor the processes at metal interface in real time without labeling requirements.Instrument SPR-2004 can sense two areas in one channel and get two signals at same time in one test.One signal is the graph of the reaction;the other is the graph of reference.SPR biochip is modified with dextran,and only reaction area can be used to immobilize the protein.Two methods of antibody immobilization on chip were tested.One was to immobilize directly,the other was to immobilize protein A firstly and then the antibody was caught by immobilized protein A.The latter was chosen as suitable for retention of the native binding ability with virus of antibody.The latter chip was used to detect SARS-Cov.The signal of detection reached to 60 units within 40 min.It was 55 units even after reference.
基金supported by the National Funds for Distinguished Young Scientists of China (No. 41225004)Guangdong Province Higher Vocational Colleges & Schools Pearl River Scholar Funded Scheme,the Ministry of Environmental Protection of China (No. 201109020)the National Natural Science Foundation of China (No. 41101483)
文摘Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as well as dead cells revealed that both extracellular adsorption and intracellular accumulation were involved in the Pb2＋removal from the liquid phase. Of the sequestered Pb（II）, 8.5% was held by physical entrapment within the cell wall, 43.3% was held by ion-exchange, 9.7% was complexed with cell surface functional groups or precipitated on the cell surface, and 38.5% was intracellularly accumulated.Complexation of Pb2＋with carboxyl, hydroxyl, carbonyl, amido, and phosphate groups was demonstrated by Fourier transform infrared spectroscopic analysis. Precipitates of Pb5（PO4）3OH, Pb5（PO4）3Cl and Pb10（PO4）6（OH）2that formed on the cell surface during the biosorption process were identified by X-ray diffraction analysis. Transmission electron microscopy–energy dispersive spectroscopic analysis confirmed the presence of the Pb（II）precipitates and that Pb（II） could be sequestered both extracellularly and intracellularly.Incubation with B. subtilis DBM significantly decreased the amount of the weak-acid-soluble Pb fraction in a heavy-metal-contaminated soil, resulting in a reduction in Pb bioavailability, but increased the amount of its organic-matter-bound fraction by 71%. The ability of B.subtilis DBM to reduce the bioavailability of soil Pb makes it potentially useful for bacteria-assisted phytostabilization of multi-heavy-metal-contaminated soil.
