In this research,an electrochemical aptasensor was made for the detection of tetracycline(TET)antibiotic in food samples.The graphite sheet was modified for the first time by electrochemical co-polymerization of anthr...In this research,an electrochemical aptasensor was made for the detection of tetracycline(TET)antibiotic in food samples.The graphite sheet was modified for the first time by electrochemical co-polymerization of anthranilic acid and aniline,which increases the active surface and electrical conductivity of the electrode and is also a suitable substrate for covalent bonding with aptamers.This electrode was examined and characterized by electrochemical methods,Fourier transform infrared(FTIR)spectroscopy,atomic force microscopy(AFM),field emission scanning electron microscopy(FESEM),and X-ray energy dispersive(EDS)techniques.Then,the Apt-TET aptamer sequence was self-assembled on the electrode to increase the selectivity of the electrode response.The optimization of important parameters including the TET detection time,aptamer immobilization time,and Apt-TET aptamer concentration was performed.The aptasensor was used to measure the TET by differential pulse voltammetry(DPV),and electrochemical impedance spectroscopy(EIS)techniques in 0.1 M KCl solution in the presence of Fe(CN)_(6)^(4-/3-)redox prob.The proposed aptasensor has a very wide linear range from 1×10^(-6)to 1×10^(-16)M with a detection limit of 3.3×10^(-17)M.The developed aptasensor was successfully applied for the determination of TET in milk,egg,and honey samples.展开更多
he nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process.The microstructure of the composites was analyzed by X-ray diffraction （XRD）,and the final phase composition...he nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process.The microstructure of the composites was analyzed by X-ray diffraction （XRD）,and the final phase composition after reduction is Al2O3,metal Fe and graphite crystal.Scanning electron microscopy （SEM） images show that the particle size of Fe is about 20 nm,and the lamellae thickness of the graphite is about 30 nm.Then,the dielectric properties and conductive mechanism of the composites were investigated experimentally in the frequency range of 0.01-1.00 GHz by impedance analyzer.The results show that the real part of permittivity of composites increases with Fe3＋ concentration,which is due to the increase in interfacial polarization between Fe and A12O3 and the three-dimensional network of lamellar graphite formation.Therefore,tunable microtopography and electrical parameters of nano-graphite sheet/alumina composites can be realized by changing Fe3＋ concentration.展开更多
The structural, electronic and magnetic properties of the hydroxylated graphitic Zinc oxide (ZnO) sheet were studied using the density functional theory. We found that the hydroxylation can induce a magnetic moment of...The structural, electronic and magnetic properties of the hydroxylated graphitic Zinc oxide (ZnO) sheet were studied using the density functional theory. We found that the hydroxylation can induce a magnetic moment of 1.0 μB per unit cell and turn graphitic ZnO sheet from semiconductor into half metal for the three studied hydroxylated configurations with a half-metal gap up to 0.60 eV. The relative stability of each situation was also discussed and the structure for hydroxyl absorbed above the hexagonal ring of ZnO sheet was the most steady. The prominent electronic and magnetic properties may endow 2D ZnO sheet great opportunity in future spintronics.展开更多
基金the partial support of this work from the Research Council of the Iran University of Science and Technology.
文摘In this research,an electrochemical aptasensor was made for the detection of tetracycline(TET)antibiotic in food samples.The graphite sheet was modified for the first time by electrochemical co-polymerization of anthranilic acid and aniline,which increases the active surface and electrical conductivity of the electrode and is also a suitable substrate for covalent bonding with aptamers.This electrode was examined and characterized by electrochemical methods,Fourier transform infrared(FTIR)spectroscopy,atomic force microscopy(AFM),field emission scanning electron microscopy(FESEM),and X-ray energy dispersive(EDS)techniques.Then,the Apt-TET aptamer sequence was self-assembled on the electrode to increase the selectivity of the electrode response.The optimization of important parameters including the TET detection time,aptamer immobilization time,and Apt-TET aptamer concentration was performed.The aptasensor was used to measure the TET by differential pulse voltammetry(DPV),and electrochemical impedance spectroscopy(EIS)techniques in 0.1 M KCl solution in the presence of Fe(CN)_(6)^(4-/3-)redox prob.The proposed aptasensor has a very wide linear range from 1×10^(-6)to 1×10^(-16)M with a detection limit of 3.3×10^(-17)M.The developed aptasensor was successfully applied for the determination of TET in milk,egg,and honey samples.
基金financially supported by the National Natural Science Foundation of China(Nos.50772061 and 51172131)
文摘he nano-graphite sheet/alumina composites were prepared in situ by a facile impregnation-reduction process.The microstructure of the composites was analyzed by X-ray diffraction （XRD）,and the final phase composition after reduction is Al2O3,metal Fe and graphite crystal.Scanning electron microscopy （SEM） images show that the particle size of Fe is about 20 nm,and the lamellae thickness of the graphite is about 30 nm.Then,the dielectric properties and conductive mechanism of the composites were investigated experimentally in the frequency range of 0.01-1.00 GHz by impedance analyzer.The results show that the real part of permittivity of composites increases with Fe3＋ concentration,which is due to the increase in interfacial polarization between Fe and A12O3 and the three-dimensional network of lamellar graphite formation.Therefore,tunable microtopography and electrical parameters of nano-graphite sheet/alumina composites can be realized by changing Fe3＋ concentration.
基金Funded by the National Natural Science Foundation of China(Grant No. 10874052)Foundation for the Author of NationalExcellent Doctoral Dissertation of China (Grant No. 200726)
文摘The structural, electronic and magnetic properties of the hydroxylated graphitic Zinc oxide (ZnO) sheet were studied using the density functional theory. We found that the hydroxylation can induce a magnetic moment of 1.0 μB per unit cell and turn graphitic ZnO sheet from semiconductor into half metal for the three studied hydroxylated configurations with a half-metal gap up to 0.60 eV. The relative stability of each situation was also discussed and the structure for hydroxyl absorbed above the hexagonal ring of ZnO sheet was the most steady. The prominent electronic and magnetic properties may endow 2D ZnO sheet great opportunity in future spintronics.
