Antibody spots were used to demonstrate that cells with a specific antigen on the membrane can be captured selectively and simply. By dropping a few microliters of solution containing antibody, antibody spots were prepared on three substrates: glass modified with amino group, glass modified with amino group with high density, and polystyrene substrate. Cells with specific surface antigen were captured on the antibody spots after the substrates were washed, but almost no cell without antigen was captured. The densities of cells captured on spots were estimated. Results show that the highest density occurred on the polystyrene substrate. Almost equal densities of captured cells were obtained for spots prepared using various volumes of dropped solutions（0.5-5.0 μL）. Mixtures of cells with and without surface antigen were dropped on the antibody spot to investigate the selective capture capability. When cells with antigen were treated with fluorescent molecules, fluorescent signals were observed from almost all captured cells. In contrast, no captured cell displayed fluorescence when cells without antigen were treated. The results indicate that the cells with antigen were captured on the antibody spots by an immunorecognition event between the antibody on the substrate and the antigen expressed on the cell membrane. The method does not require target labeling. Moreover, a single assay was completed in as little as 10 min. The present simple and rapid method might prove useful in widely various characterization applications for surface antigens on cell membranes. Results show that human acute monocytic leukemia cell line with the surface antigen C3b receptor can be captured with anti-C3b antibody.
Using the PVD arc ion plating method, Cr-B-N, Cr-C-N, and Cr-O-N coatings with different B, C, and O contents, and CrN coatings were prepared. Thermal stability of the coatings during annealing in air at temperatures of 473-1073 K was investigated. X-ray diffraction measurements showed that all diffraction peaks of cubic CrN phase sharpened and shifted to a higher angle as the annealing temperature increased. At temperatures higher than 773 K, the grain sizes of most coatings became larger, and hardness decreased. The CrN and the Cr-C-N coatings respectively began decomposing at temperatures higher than 773 K and 873 K. As the amount of the third element increased, changes of the diffraction peaks decreased and the decrease of hardness was restricted. The grain size and hardness of the Cr-O-N coating with the most O content changed little after annealing. TEM observations revealed that the apparent grain growth of the CrN coating occurred during annealing, but fine microstructures of CrB-N, Cr-C-N, and Cr-O-N coatings were almost unaffected by annealing. Nanometer-scale periodic lines of the Cr-O-N coating did not change after annealing. Subsequent AES analysis revealed that the periodic lines of the Cr-O-N coating indicated a change of O concentration. The period was maintained after annealing at 873 K.