title: Stimuli-responsive chitosan/poly (N-isopropylacrylamide) semi-interpenetrating polymer networks: effect of pH and temperature on their rheological and swelling properties.
abstract: The aim of this work was to synthesize semi-interpenetrating polymer networks (semi-IPNs) by free radical polymerization of N-isopropylacrylamide [poly (NIPAAm)], in the presence of chitosan (CHI), and to study the effect of pH and temperature changes on their rheological and swelling properties. The semi-IPNs are thermally stable up to about 400 °C and the presence of CHI increases the thermal degradation rate compared to bare poly (NIPAAm). The prepared systems presents a well-defined porosity and proved to be non-toxic, in vitro, on human embryonic skin fibroblast, thus offering appropriate support for cell proliferation. The semi-IPNs present, at physiological pH, swelling degrees well below those of the pure poly (NIPAAm). Differently, at acidic pH, the CHI macromolecules are protonated and become much more permeable to the diffusion of water giving a swelling degree that approaches that of bare poly (NIPAAm). The viscoelastic moduli of the semi-IPNs increase as a function of pH while the LCST remain unchanged. Moreover, the semi-IPNs viscoelastic moduli increase with the increase of CHI content and, in particular, the difference between the elastic modulus before and after the sol/gel transition is higher for the semi-IPN than for bare poly (NIPAAm) just at about physiological conditions.
authors.affiliation: Institute of Polymer Science and Technology, CSIC, Juan de la Cierva 3, 28006, Madrid, Spain.|CIBER-BBN, Monforte de Lemos 3-5, pabellón 11 planta 0, 28029, Madrid, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Fernández-Gutiérrez
authors.affiliation: CRIB@IIT - Istituto Italiano Tecnologia, P.le Tecchio, 80, 80125, Naples, Italy.
authors.forename: Sabato
authors.initials: S
authors.lastname: Fusco
authors.affiliation: Dipartimento di Farmacia, Università di Napoli Federico II, Via D. Montesano 49, Naples, Italy.|Interdisciplinary Research Centre on Biomaterials - CRIB, Università di Napoli Federico II, P.le Tecchio, 80, Naples, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Mayol
authors.affiliation: Institute of Polymer Science and Technology, CSIC, Juan de la Cierva 3, 28006, Madrid, Spain.|CIBER-BBN, Monforte de Lemos 3-5, pabellón 11 planta 0, 28029, Madrid, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: San Román
authors.affiliation: Institute for Polymers, Composites and Biomaterials (IPCB), National Research Council, Mostra d'Oltremare Pad. 20, Viale J. F. Kennedy 54, 80125, Naples, Italy. bassunta@unina.it.
authors.forename: Assunta
authors.initials: A
authors.lastname: Borzacchiello
authors.affiliation: Institute for Polymers, Composites and Biomaterials (IPCB), National Research Council, Mostra d'Oltremare Pad. 20, Viale J. F. Kennedy 54, 80125, Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ambrosio
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002448:Cell Adhesion; D049109:Cell Proliferation; D002470:Cell Survival; D048271:Chitosan / Q000737:chemistry*; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D012212:Rheology; D012867:Skin / Q000166:cytology; D013696:Temperature
chemical_list: D000180:Acrylic Resins; C052970:poly-N-isopropylacrylamide; D048271:Chitosan