A procedure for immobilization of well-defined quantities of oligodeoxyribonucleotides (ODNs) to a versatile nylon support is described. The solid support, a nylon-6/6 bead, is covalently coated with poly(ethyleneimine) to provide a reactive spacer-arm for attachment of ODNs. 5'-Aminohexyl-tailed ODNs are selectively activated using 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride) and then covalently attached to the bead via the triazine moiety. The modified nylon support has a low level of binding of nonspecific nucleic acid and efficiently captures both RNA and DNA targets.