In this study, poly(N,N-dimethylacrylamide) grafted chitosan (PDMAAm-g-CT) hydrogels were prepared for deoxyribonucleic acid (DNA) adsorption. Instead of directly grafting the N,N-dimethylacrylamide (DMAAm) monomer onto the chitosan (CT) chains, poly(N,N-dimethylacrylamide) with carboxylic acid end group (PDMAAm-COOH) was firstly synthesized by free-radical polymerization using mercaptoacetic acid (MAAc) as the chain-transfer agent and then grafted onto the CT having amino groups. The synthesis of PDMAAm-COOH and its grafting onto the CT chains were confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. From gel permeation chromatography measurements, the number-average molecular weight ((M) over bar (n)) and polydispersity index of PDMAAm-COOH were found as 2400 g/mol and 2.3, respectively. The PDMAAm-g-CT hydrogels were utilized as the adsorbents in DNA adsorption experiments conducted at +4 degrees C in a trisEDTA solution of pH 7.4. The hydrogels produced with higher PDMAAm-COOH content exhibited higher DNA adsorption capacity. The DNA adsorption capacity up to 4620 mu g DNA/g dry gel could be achieved with the PDMAAm-g-CT hydrogels prepared in 80.0 wt % PDMAAm-COOH feed concentration. This value is approximately seven times higher than that of CT alone. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1420-1425, 2011