A Highly Selective, Biofunctional Surface for Molecule/Cell Sorting

We report in this paper an approach to the effective capture of IgM antibodies from antisera and solutions based on the formation of a carpet of molecules exposing thiols off a surface. Surfaces of different nature, such as OH-exposing (glass, SiO2, metal oxides, etc.) and noble metal ones (Au, Ag, etc.), have been first functionalized in the liquid phase by suitable chemistry [3-(mercaptopropyl)trimethoxysilane or 1,4-benzenedimethanethiol]. The resulting exposed SH moieties have been further used for binding anti-A, -B, and -D IgM molecules from goat sera via a thiol exchange reaction involving the J chain and other disulfide bonds present in the IgM molecular structure. Antibodies preserve their functional activity at the surface and appear to be able to bind specifically erythrocytes of the proper group in a fast and reliable way. These results can be generalized to the use of any kind of IgM antibody and can be valuable in surface biofunctionalization in the fields of biosensors and immunoassays.