IMAGING OF SINGLE ANTIGENS, ANTIBODIES, AND SPECIFIC IMMUNOCOMPLEX FORMATION BY SCANNING FORCE MICROSCOPY

The most sensitive analytical techniques available today for detecting immune assay complexes are radio or enzyme immune analytical techniqu es, by which quantities of 10(7)-10(8) analyte molecules can be detect ed. With the introduction of scanning force microscopy, a new method f or detecting biological processes became available. Here, we examine t he feasibility of using scanning force microscopy as a biosensitive to ol. We demonstrate that single or multiple rabbit anti-human serum alb umin molecules form complexes with preadsorbed single human serum albu min molecules on mica. However, no interaction is observed between hum an immunoglobulin G molecules and preadsorbed single albumin molecules ; only separate antigens and antibodies are observed at random positio ns on the mica. This shows the ability of scanning force microscopy to act as a biosensor for detection of immunocomplexes, and to act as a very powerful tool to study molecule-surface interactions in general.