Biolithography : selective joining using antibody-antigen reactions

Abstract

Biolithography is a contribution to the field of Solid Free Form Fabrication. Part production is based on selective joining using antibody- antigen reactions, where the selectively is based on the thermal sensitivity of such proteins. Antibodies and antigens can be chemically immobilized to a variety of substrate materials: polymeric, ceramic and metallic. In the present investigation, antibody coated 1 [mu]m polystyrene beads and antigen coated glass surface substrates, as well as, antigen solutions were used. Both antibodies and antigens were multivalent i.e. have more that one binding site for each other; thus, two antibody coated beads could be held together by one antigen. Selective deposition was demonstrated by thermally deactivating antigen coated onto glass and precipitating antibody coated beads. Bead deposition was selective to the regions of remaining active antigens; thus, revealing the defined deactivated region. Thermal deactivation of the antigen coated substrate was first demonstrated with a 90°C water jet and improved using an argon ion laser which produced line widths on the order of tens of microns. Selective definition of geometry was an extension of the coating process precipitating not one but two bead layers and linking beads using antigen in solution. The thermal deactivation mechanism was a modified 90°C water jet that had line width resolution on the order of millimeters. Line definition was on both antigen coated bases and bound bead bases; thus, thermal deactivation was effective on both immobilized antigen (glass) and antibody (bead). The selective deposition of antibody coated substrate was demonstrated by thermally deactivating immobilized antigens and antibodies on surface substrates. Definition resolution was dependent on the thermal deactivation mechanism used.