title: Tunable thermo-responsive hydrogels: synthesis, structural analysis and drug release studies.
abstract: Thermo-responsive hydrogel films, synthesized by UV-initiated radical polymerization, are proposed as delivery devices for non-steroidal anti-inflammatory drugs (Diclofenac sodium and Naproxen). N-isopropylacrylamide and N,N'-ethylenebisacrylamide were chosen as thermo-sensitive monomer and crosslinker, respectively. Infrared spectroscopy was used to assess the incorporation of monomers into the network, and the network density of hydrogel films was found to strictly depend on both feed composition and film thickness. Calorimetric analyses showed negative thermo-responsive behaviour with shrinking/swelling transition values in the range 32.8-36.1°C. Equilibrium swelling studies around the LCST allowed the correlation between the structural changes and the temperature variations. The mesh size, indeed, rapidly changed from a collapsed to a swollen state, with beneficial effects in applications such as size-selective permeation or controlled drug delivery, while the crosslinking degree, the film thickness, and the loading method deeply influenced the drug release profiles at 25 and 40°C. The analysis of both 3D-network structure, release kinetics and diffusional constraints at different temperatures was evaluated by mathematical modelling.
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cirillo
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy.
authors.forename: Tania
authors.initials: T
authors.lastname: Spataro
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Curcio
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy. Electronic address: g.spizzirri@unical.it.
authors.forename: U Gianfranco
authors.initials: UG
authors.lastname: Spizzirri
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy.
authors.forename: Fiore Pasquale
authors.initials: FP
authors.lastname: Nicoletta
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy.
authors.forename: Nevio
authors.initials: N
authors.lastname: Picci
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edificio Polifunzionale, Rende, CS 87036, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Iemma
mesh_terms: D000178:Acrylamides; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000493:pharmacokinetics; D003692:Delayed-Action Preparations / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics; D004008:Diclofenac / Q000737:chemistry / Q000493:pharmacokinetics; D006358:Hot Temperature; D020100:Hydrogels / Q000138:chemical synthesis / Q000737:chemistry; D009288:Naproxen / Q000737:chemistry / Q000493:pharmacokinetics; D014466:Ultraviolet Rays
chemical_list: D000178:Acrylamides; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003692:Delayed-Action Preparations; D020100:Hydrogels; D004008:Diclofenac; D009288:Naproxen; C067295:N-isopropylacrylamide
keywords: Drug delivery systems; Radical polymerization; Structural analysis; Thermo-responsive hydrogels