Observation of interaction force in large area between actin modified surface and actin antibody modified microsphere...

In order to observe the force interaction in large areas, a novel force detection probe was fabricated by two-photon absorbed photopolymerization (TPAP) techniques. The probe was based on a commercial cantilever, and a docking structure for adopting a microsphere immobilized with actin antibody was fabricated by the TPAP techniques. The commercial AFM tip was also modified with the antibody for comparison. Using force curve measurement, the interaction force was compared between the modified probes and the sample surface which was immobilized with actin using a spotting system. The adhesive force of 1.3 nN was measured applying the commercial cantilever. The value was comparable to the measured interaction force of 130 nN applying the microsphere modified cantilever. The measured adhesive force of the novel probe was 100-fold larger than that obtained by the sharp AFM cantilever tip. This strong adhesive force of the microsphere modified cantilever to actin is explainable by the large contact area between the microsphere and the sample surface.