Figure 3

Principle for magnetic pre-concentration procedure. Whereas the antibody in the present study was anti-rabbit IgG and the antigen, rabbit IgG, the terms “antibody” and “antigen” are used to illustrate the generality of the approach. In step I, antigens are captured from serum by the antibodies conjugated to magnetic particles, MPs. Antigen-antibody-MP complexes are then concentrated using an external magnet to a small volume in the eppendorf tube while simultaneously exchanging serum for an optimized biological buffer (step II). Actin filaments conjugated with antibodies are then added and a second magnetic concentration step is performed (step III). This step is expected to leave actin filaments without MPs in the supernatant (that is removed) and those that have cross-linked MPs in the pellet. The latter are re-dispersed in buffer B and added to a flow cell (step IV) with surfaces coated with heavy meromyosin motor fragments for specific binding of actin filaments (e.g. actin-antibody-antigen-antibody-MP complexes as illustrated) and molecular motor driven transportation.