An interpenetrating polymer network (IPN) containing natural DNA was prepared by cross-linking polyvinyl alcohol (PVA) with a glutaraldehyde (GA) reagent and then cross-linking DNA with UV irradiation. This DNA/PVA IPN structure could selectively bind chemicals with affinity for DNA, and adsorb L-tryptophan (L-Trp) with a high chiral-selectivity over D-Trp. More than ten times more L-Trp was adsorbed on the DNA/PVA IPN membrane than D-Trp. This readily available adsorbent has high prospects in diverse practical applications, such as the removal of pollutants from water, purification of medicines, as well as separation of enantiomers.