Poly(N-isopropylacrylamide) based pH- and temperature-sensitive ampholytic hydrogels with tunable mechanical, swelling and drug release properties

Abstract

pH-/temperature-sensitive ampholytic poly(N-isopropylacrylamide) (PNIPAAm) hydrogels containing N-[3-(dimethylamino)propyl]methacrylamide-itaconic acid (DMAPMAAm-IA) and DMAPMAAm-AMPS (2-acrylamido-2-methylpropane sulfonic acid) comonomer pairs have been designed and then synthesized. The results showed that (i) disk diameters and transparencies in the range of pH 2–12 increased only with increasing content of AMPS in the ampholytic NIPAAm/DMAPMAAm/AMPS hydrogels containing 10.0 mol % of DMAPMAAm + AMPS mixtures; (ii) maximum compressive strengths of NIPAAm/IA (62.5 ± 10.0 kPa) was higher than NIPAAm/AMPS (26.9 ± 1.1 kPa) hydrogels in DDW at 37 °C. (iii) In case of DFNa release, the decreasing values of n (≈0.30–0.50) indicated that ampholytic PNIPAAm hydrogels served as diffusion barrier.