Preparation of poly(N,N-dimethylacrylamide) and poly(acrylamide) grafted chitosan hydrogels and their use for DNA adsorption

In this study, comb-type graft hydrogels composed of crosslinked chitosan network and grafted poly(N, N-dimethlyacrylamide) or poly(acrylamide) were prepared. Semitelechelic polymers with carboxylic acid end group were synthesized by free radical polymerization technique using mercaptoacetic acid as the chain transfer agent. The structure of the telechelic polymers and grafted hydrogels was confirmed by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FT-IR). Surface morphplogy of the hydrogels was examined by Scanning Electron Microscopy (SEM). In additon, surface energy components of these hydrogels were also calculated by contact angle measurements. It was observed that the grafted hydrogels have higher surface energies than that of crosslinked chitosan networks. Swelling behaviors of the hydrogels were investigated as a function of pH and temperature. It was observed that all the hydrogels have highest swelling ratios at low temperature and pH?s. Comb-type grafted hydrogels were used as sorbents for DNA adsorption. DNA adsorption capacities of the hydrogels were vii determined against the amount of grafting, time and DNA concentration at 4 ºC and 37 ºC. The hydrogels with higher amount of DMA and AAm exhibited higher equilibrium DNA adsorption capacity. The maximum adsorption capasities of these hydrogels were observed at 37 ºC in all conditions. DNA release characteristics were studied to observe if the hydrogels could reuse for biomedical applications. Key Words :DNA adsorption, chitosan, Comb type grafted, poly(acrylamide), poly(N,N-dimethylacrylamide)