title: Grafted thermo-responsive gelatin microspheres as delivery systems in triggered drug release.
abstract: In this paper, a novel class of microspheric hydrogels was synthesized by grafting of N-isopropyacrylamide (NIPAAm) with gelatin. The possibility of inserting commercial gelatin in a crosslinked structure bearing thermo-sensitive moieties, by radical process, represents an interesting innovation that significantly improves the device performance, opening new applications in biomedical and pharmaceutical fields. This synthetic approach allows a modification of the polymeric network composition, producing hydrogels with suitable physico-chemical properties and a transition temperature higher than NIPAAm homopolymers. The incorporation of monomers into the network was confirmed by infrared spectroscopy, and the composition of the polymerization feed was found to strictly influence the network density and the shape of hydrogels. Thermal analyses showed negative thermo-responsive behaviour with shrinking/swelling transition values in the temperature range 34.6-34.8 degrees C, according to the amount of the hydrophilic portions in the network. In order to test the preformed materials as drug carriers, diclofenac sodium salt was loaded into the spherical microparticles. After the determination of the drug entrapment percent, drug release profiles in media at different temperature were analysed. By using semi-empirical equations, the release mechanism was extensively studied and the diffusional contribution was evaluated.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università della Calabria, Arcavacata di Rende (CS), Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Curcio
authors.forename: U
authors.initials: U
authors.lastname: Gianfranco Spizzirri
authors.forename: Francesca
authors.initials: F
authors.lastname: Iemma
authors.forename: Francesco
authors.initials: F
authors.lastname: Puoci
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cirillo
authors.forename: Ortensia I
authors.initials: OI
authors.lastname: Parisi
authors.forename: Nevio
authors.initials: N
authors.lastname: Picci
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D004008:Diclofenac / Q000737:chemistry*; D004058:Diffusion; D004337:Drug Carriers; D004339:Drug Compounding; D004355:Drug Stability; D005780:Gelatin / Q000737:chemistry*; D020100:Hydrogels; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D008956:Models, Chemical; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013678:Technology, Pharmaceutical / Q000379:methods; D044366:Transition Temperature
chemical_list: D000178:Acrylamides; D000894:Anti-Inflammatory Agents, Non-Steroidal; D004337:Drug Carriers; D020100:Hydrogels; D004008:Diclofenac; D005780:Gelatin; C067295:N-isopropylacrylamide