Gold-silver core-shell nanorods were deposited on a glass plate, and the plate was immersed in hydrogen peroxide solution to oxidize the silver shells. When catalase and horseradish peroxidase (HRP) were deposited on the plates, they decomposed the hydrogen peroxide at the surface and suppressed the oxidation of the silver shells. The surface densities of catalase and HRP were 3.1 mu g cm(-2) and 5 ng cm(-2), respectively, comparable to detection limits of conventional enzyme-linked immunosorbent assays. Our protocol has the potential for application in a sensitive and quantitative immunoassay.