将生物素标记的DNA与链霉亲和素(streptavidin,STV)按4∶1摩尔比连接,用原子力显微镜(atomic force microscope,AFM)对混合物表征,观察到所有可能的几种DNA-STV复合物。并按照不同摩尔浓度比和孵育时间配制DNA与STV混合液,探讨了影响结...将生物素标记的DNA与链霉亲和素(streptavidin,STV)按4∶1摩尔比连接,用原子力显微镜(atomic force microscope,AFM)对混合物表征,观察到所有可能的几种DNA-STV复合物。并按照不同摩尔浓度比和孵育时间配制DNA与STV混合液,探讨了影响结合效率的因素,初步得到用生物素-链霉亲和素系统批量制备1STV-1DNA单分子复合物的最佳制备条件,为未来单分子DNA的大规模快速制备奠定了基础。展开更多
This article aims to establish an efficient assay for screening monoclonal antibodies （McAbs） against the membrane proteins of chicken embryo fibroblast （CEF） for further studies of the cellular receptors of infec...This article aims to establish an efficient assay for screening monoclonal antibodies （McAbs） against the membrane proteins of chicken embryo fibroblast （CEF） for further studies of the cellular receptors of infectious bursal disease virus （IBDV）. McAbs against the membrane proteins of CEF were prepared by cell fusion. The monolayer CEF pre-incubated with the CEF-specific McAbs for 2 h were infected with IBDV and incubated with F22-EA6-biotin postinfection. Then, the cells were reacted with streptavidin-horseradish peroxidase （HRP） and finally stained by 3-amino-9-ethylcarbazole （AEC）. The inhibitive percentage of IBDV infection was calculated by counting the IBDV-infected cells to determine the inhibition efficiency of the CEF-specific McAbs. Compared with the control cells, the IBDV-infected cells pretreated with CEF-specific antibody significantly decreased; supernatant fluids of a total of 768 hybridomas were analyzed. The results of immunohistochemistry assays showed that six of them （1A5, 1H11, 2B 12, 3G1, 4D10, and 4B8） have the abilities to block the infection of IBDV to CEF, among which 4B8 can perfectly block the infection. This novel method is a sensitive and specific assay for the screening of CEF membrane protein-specific McAbs, which can block the infection of IBDV to CEF, and these McAbs can be used for the further investigations of the cellular receptors of IBDV.展开更多
Kanamycin is an aminoglycoside antibiotic used increasingly in human and veterinary medicine. However, kanamycin residues in food can cause serious side effects, Here we reported the preparation of polyclonal antibody...Kanamycin is an aminoglycoside antibiotic used increasingly in human and veterinary medicine. However, kanamycin residues in food can cause serious side effects, Here we reported the preparation of polyclonal antibody and the development of an indirect competitive biotin-streptavidin-amplified-based enzyme-linked immunosorbent assay（BA-ELISA） that can sensitively and specifically detect kanamycin residues in milk and honey. The immtmogen and coating antigen were synthesized by covalently linking kanamycin to carrier proteins using the carbodiimide method. The anti-kanamycin polyclonal antibodies were obtained from immunized rabbits. The key assay parameters were investigated and optimized. The results show that under optimum conditions, the limit of detection for kanamycin is 0.07 ng/mL and the ICs0 is 6.48 ng/mL. Cross-reactivity values of the antibody with four kanamycin analogues are all 〈1%. Trace amounts of kanamycin in milk and honey samples can be detected by this novel BA-ELISA method successfully with satisfactory recoveries of 91.0%-103.3%. The developed protocol was also validated against liquid chromatography-mass spectrometry, returning a significant correlation. These results indicate that BA-ELISA is a viable option for monitoring kanamycin residues in milk and honey.展开更多
Titanium dioxide （TiO2） nanoparticles are produced for many different purposes, including development of therapeutic and diagnostic nanoparticles for cancer detection and treatment, drug delivery, induction of DNA d...Titanium dioxide （TiO2） nanoparticles are produced for many different purposes, including development of therapeutic and diagnostic nanoparticles for cancer detection and treatment, drug delivery, induction of DNA double-strand breaks, and imaging of specific cells and subcellular structures. Currently, the use of optical microscopy, an imaging technique most accessible to biology and medical patholog36 to detect TiO2 nanoparticles in cells and tissues ex vivo is limited with low detection limits, while more sensitive imaging methods （transmission electron microscopy, X-ray fluorescence microscop~ etc.） have low throughput and technical and operational complications. Herein, we describe two in situ post- treatment labeling approaches to stain TiO2 nanoparticles taken up by the cells. The first approach utilizes fluorescent biotin and fluorescent streptavidin to label the nanoparticles before and after cellular uptake; the second approach is based on the copper-catalyzed azide-alkyne cycloaddition, the so-called Click chemistry, for labeling and detection of azide-conjugated TiO2 nanoparticles with alkyne- conjugated fluorescent dyes such as Alexa Fluor 488. To confirm that optical fluorescence signals of these nanoparticles match the distribution of the Ti element, we used synchrotron X-ray fluorescence microscopy （XFM） at the Advanced Photon Source at Argonne National Laboratory. Titanium-specific XFM showed excellent overlap with the location of optical fluorescence detected by confocal microscopy. Therefore, future experiments with TiO2 nanoparticles may safely rely on confocal microscopy after in situ nanoparticle labeling using approaches described here.展开更多
文摘将生物素标记的DNA与链霉亲和素(streptavidin,STV)按4∶1摩尔比连接,用原子力显微镜(atomic force microscope,AFM)对混合物表征,观察到所有可能的几种DNA-STV复合物。并按照不同摩尔浓度比和孵育时间配制DNA与STV混合液,探讨了影响结合效率的因素,初步得到用生物素-链霉亲和素系统批量制备1STV-1DNA单分子复合物的最佳制备条件,为未来单分子DNA的大规模快速制备奠定了基础。
基金supported by the National Natural Science Foundation of China (30671561)the National Key Technology R&D Program of China (2006BAD06A04-6)the National Basic Research Program of China(2005CB523203)
文摘This article aims to establish an efficient assay for screening monoclonal antibodies （McAbs） against the membrane proteins of chicken embryo fibroblast （CEF） for further studies of the cellular receptors of infectious bursal disease virus （IBDV）. McAbs against the membrane proteins of CEF were prepared by cell fusion. The monolayer CEF pre-incubated with the CEF-specific McAbs for 2 h were infected with IBDV and incubated with F22-EA6-biotin postinfection. Then, the cells were reacted with streptavidin-horseradish peroxidase （HRP） and finally stained by 3-amino-9-ethylcarbazole （AEC）. The inhibitive percentage of IBDV infection was calculated by counting the IBDV-infected cells to determine the inhibition efficiency of the CEF-specific McAbs. Compared with the control cells, the IBDV-infected cells pretreated with CEF-specific antibody significantly decreased; supernatant fluids of a total of 768 hybridomas were analyzed. The results of immunohistochemistry assays showed that six of them （1A5, 1H11, 2B 12, 3G1, 4D10, and 4B8） have the abilities to block the infection of IBDV to CEF, among which 4B8 can perfectly block the infection. This novel method is a sensitive and specific assay for the screening of CEF membrane protein-specific McAbs, which can block the infection of IBDV to CEF, and these McAbs can be used for the further investigations of the cellular receptors of IBDV.
基金Supported by the National Natural Science Foundation of China（No.21675008）, the Natural Science Foundation of Beijing, China（No.2132048） and the Fundamental Research Funds for the Central Universities, China（No.JDl 516）.
文摘Kanamycin is an aminoglycoside antibiotic used increasingly in human and veterinary medicine. However, kanamycin residues in food can cause serious side effects, Here we reported the preparation of polyclonal antibody and the development of an indirect competitive biotin-streptavidin-amplified-based enzyme-linked immunosorbent assay（BA-ELISA） that can sensitively and specifically detect kanamycin residues in milk and honey. The immtmogen and coating antigen were synthesized by covalently linking kanamycin to carrier proteins using the carbodiimide method. The anti-kanamycin polyclonal antibodies were obtained from immunized rabbits. The key assay parameters were investigated and optimized. The results show that under optimum conditions, the limit of detection for kanamycin is 0.07 ng/mL and the ICs0 is 6.48 ng/mL. Cross-reactivity values of the antibody with four kanamycin analogues are all 〈1%. Trace amounts of kanamycin in milk and honey samples can be detected by this novel BA-ELISA method successfully with satisfactory recoveries of 91.0%-103.3%. The developed protocol was also validated against liquid chromatography-mass spectrometry, returning a significant correlation. These results indicate that BA-ELISA is a viable option for monitoring kanamycin residues in milk and honey.
文摘Titanium dioxide （TiO2） nanoparticles are produced for many different purposes, including development of therapeutic and diagnostic nanoparticles for cancer detection and treatment, drug delivery, induction of DNA double-strand breaks, and imaging of specific cells and subcellular structures. Currently, the use of optical microscopy, an imaging technique most accessible to biology and medical patholog36 to detect TiO2 nanoparticles in cells and tissues ex vivo is limited with low detection limits, while more sensitive imaging methods （transmission electron microscopy, X-ray fluorescence microscop~ etc.） have low throughput and technical and operational complications. Herein, we describe two in situ post- treatment labeling approaches to stain TiO2 nanoparticles taken up by the cells. The first approach utilizes fluorescent biotin and fluorescent streptavidin to label the nanoparticles before and after cellular uptake; the second approach is based on the copper-catalyzed azide-alkyne cycloaddition, the so-called Click chemistry, for labeling and detection of azide-conjugated TiO2 nanoparticles with alkyne- conjugated fluorescent dyes such as Alexa Fluor 488. To confirm that optical fluorescence signals of these nanoparticles match the distribution of the Ti element, we used synchrotron X-ray fluorescence microscopy （XFM） at the Advanced Photon Source at Argonne National Laboratory. Titanium-specific XFM showed excellent overlap with the location of optical fluorescence detected by confocal microscopy. Therefore, future experiments with TiO2 nanoparticles may safely rely on confocal microscopy after in situ nanoparticle labeling using approaches described here.
