The concept of using alumina nanoporous filters (AAO) modified with DNA for "label-free" detection and separation/purification of the target ss-DNA is demonstrated. The high surface density of DNA (4 x 10(12) cm(2)) and high efficiency of hybridization (ca. 70%) in combination with increased effective surface area make this system very attractive for development of various ss-DNA (or RNA) detection methods. Moderate transparency of AAO in the UV and IR regions allows direct detection of DNA hybridization by optical and IR absorption. Close to the quantitative efficiency of binding the target ss-DNA from solution using a single pass through the modified filter is observed.