Comparative Assessment of the Force Characteristics of the Interaction of the Yersinia pseudotuberculosis Lipopolysaccharide with Antibodies by Optical Trapping and Atomic Force Microscopy

A comparative assessment of the binding force of lipopolysaccharide from Yersinia pseudotuberculosis culture with monoclonal antibodies has been carried out using optical tweezers and atomic force microscopy. The features of the two techniques are discussed, which detected significant differences in the measured bond rupture force between a lipopolysaccharide-sensitized probe (a polystyrene microsphere in the case of optical tweezers and a silicon nitride cantilever tip in the case of atomic force microscopy) and a substrate (glass and mica, respectively) coated with monoclonal antibodies. In the case of atomic force microscopy, the tip of the cantilever slides along the surface of the substrate until the piezo stage stops, causing a change in the spatial structure of the sensitins and, as a result, a redistribution of the multiple bonds between the lipopolysaccharide agglomerate and antibodies. When the optical tweezers technique is used there is no significant displacement of the microsphere along the substrate surface and, unlike atomic force microscopy, the rupture of the complex bond between lipopolysaccharide and complementary antibodies is recorded as a single and short-term (1–2 ms) jump in the photodetector signal. The fixed values of the bond rupture force measured by both techniques are relative and vary depending on the selected experimental conditions. It is shown that the nonspecific component of the bond rupture force measured by atomic force microscopy is significantly higher than that determined by optical tweezers.