Supramolecular formations of antibodies by their specific molecular recognition to antigens are investigated. Linear and network supramolecular architectures have been constructed by using immunoglobulin G (IgG) and divalent or trivalent antigens, respectively. An amplification method of the detection signals for the target molecule in the biosensors based on the surface plasmon resonance (SPR) has been devised using the signal enhancement in the supramolecular assembly of the antibody with multivalent antigens. Novel dendritic supramolecular complexes are designed and prepared by using immunoglobulin M (IgM) or protein A/G as a core and IgGs as branches. One of the "antibody dendrimers" is composed of proteins with a molecular weight of about 2 million and constructed by non-covalent bonds. The dendrimer can bind antigens strongly with high specificity. The biosensor technique based on SPR shows that the antibody dendrimer has the advantage of amplification of detection signals for antigens.