The adsorption of an anti-domoic acid single-chain Fv ( scFv) antibody fragment onto a range of mesoporous silicate supports was investigated. The scFv fragment adsorbed to all materials investigated, and pI had an apparently large effect on coating, with the greatests-and fastest-adsorption found on the most negatively charged silicates. Maximal coating levels attainable did not reflect the pore diameters of the materials. The immobilized antibody was functional on all materials and bound its antigen, a naturally occurring neurotoxin produced by shellfish, in a rapidly saturating manner that suggested the antibody adsorbed in a multilayer on the mesoporous particles. The antigen: antibody ratio decreased from 1: 1.3 to < 1: 10 with increasing concentration of immobilized antibody, and the immobilized scFv exhibited no detectable reduction in domoic acid binding over a 42-day incubation period.