COLL 140 |
| Adam W. Feinberg, Dept. of Biomedical Engineering, University of Florida, P.O. Box 116400, Gainesville, FL 32611 and Anthony B. Brennan, Dept. of Material Science and Engineering, Dept. of Biomedical Engineering, University of Florida, Gainesville, FL 32611-6400. |
| To investigate the free surface of adhered porcine vascular endothelial cells (PVECs), an atomic force microscope (AFM) colloid tip was functionalized with the carbohydrate ligand sialyl Lewis X (sLeX) and used to locate P-selectin receptors on the membrane surface. The PVECs were imaged while alive using the AFM operated in force volume mode. Each force curve was analyzed for specific adhesion events corresponding to the receptor-ligand bond rupture force. A binding force of 183 ± 40 pN at a distance of 28 ± 9 nm was found for the sLeX-selectin interaction using an autocorrelation function applied to a histogram of the specific interaction forces. The force volume topographical image revealed that the selectins formed micrometer sized clusters at the periphery of the cells. This technique allowed for simultaneous mapping and quantification of binding force for receptor-ligand pairs on living cells and will be extended to other cell surface receptors. |
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Nanoscale Imaging of Biological Systems
Division of Colloid and Surface Chemistry |