Sensing Interactions Between Vimentin Antibodies and Antigens for Early Cancer Detection

This paper examines the use of polysilicon microcantilevers in the bioassay of Vimentin antigens that are presented in human-osteosarcoma (HOS) cells. Pre-calibrated atomic force microscopy (AFM) microcantilevers were functionalized with Vimentin antibodies using a two-step process that involved the application of an amine-rich polyethyleneimine (PEI) to the silicon oxide layer that is presented on unpassivated silicon surfaces. This is followed by a second step reaction between the amines at the surface and the carboxylic acid groups in the amino acid unit of the Vimentin antibody. The possible interaction between Vimentin antibody on microcantilevers and Vimentin antigens were then studied in a biofluidic chamber attached to an AFM platform. These were explored by exposing the Vimentin antibodies to increasingly small concentrations of Vimentin antigens. Static deflection in the microcantilevers was measured as a result of the surface stresses that are induced by changes in the molecular structure due to antigen-antibody interactions. The implications of the results were discussed for the early detection of cancer in biopsies.