Role of N-vinyl-2-pyrrolidinone on the thermoresponsive behavior of PNIPAm hydrogel and its release kinetics using dye and vitamin-B12 as model drug.

Temperature-sensitive hydrogels hold great promise in biological applications as they can respond to changes in physiological temperature to produce a desired effect like controlled drug delivery. In this study, a series of poly(N-isopropylacrylamide-co-N-vinyl-2-pyrrolidinone) thermosensitive hydrogels were synthesized by radical copolymerization of NIPAm with 1-vinyl-2-pyrrolidinone (NVP). By altering the initial NIPAm/NVP mole ratios, copolymers were synthesized to have their own distinctive lower critical solution temperature which was established using differential scanning calorimetry. The swelling behavior of the hydrogel was analyzed gravimetrically and it was observed that reswelling rate increases with increasing NVP mole ratio. Further characterizations of the hydrogels were per-formed using Fourier transform infrared spectroscopy and scanning electron microscopy. Release kinetics with respect to temperature was studied using methy-lene blue dye solution and vitamin B12. Kinetic modeling of the release profile revealed that the release mechanism is a non-Fickian diffusion mechanism. These results suggested that this material has potential application as intelligent drug carri-ers. The quantities of residual monomers in the PIV4 hydrogel were determined by HPLC method, and the results show almost complete conversion. [ABSTRACT FROM AUTHOR]