Continuous detection of extracellular ATP on living cells by using atomic force microscopy

Atomic force microscopy is a powerful technique used to investigate the sur face of living cells under physiological conditions. The resolution of the instrument is mainly limited by the softness of living cells and the intera ctions with the scanning tip (cantilever). Atomic force microscopy, in comb ination with myosin-functionalized cantilevers, was used in the detection o f ATP concentrations in solution and on living cells. Functionally active t ips were used to scan the surface of cells in culture and to show that the CFTR+ cell line (59) had a basal surface ATP concentration that could be de tected with atomic: force microscopy (n = 10). ATP-dependent signals were n ot detectable in cells scanned with noncoated or heat-inactivated enzyme-co ated tips (n = 9). Enzymatically active tips may serve as a model for futur e development of atomic force microscopy biosensors that can simultaneously detect topographical and biologically important compounds at the surface m icroenvironment of living cells.