title: Covalent and ionic co-cross-linking--an original way to prepare chitosan-gelatin hydrogels for biomedical applications.
abstract: The first goal of this work was to develop a method for obtaining interpenetrating gelatin (G)-chitosan (CS) networks prepared by double cross-linking (covalent followed by ionic) that exhibit hydrogel character. The second goal was to modulate their properties as a function of the preparation parameters by using neural network models. This study was therefore carried out by experiment and simulation. The covalent cross-linking resulted from the reaction between the carbonyl groups of glutaraldehyde with amino groups belonging to both polymers; the ionic cross-linking is based on the interaction between tripolyphosphate anions and protonated amine groups (ammonium ions) of the polymers. The total cross-linking density (indirectly assessed by estimating the water swelling capacity) and the ability to include hydrosoluble bioactive principles are influenced by the following process parameters: the CS/G ratio, the amount of ionic cross-linker, and the ionic cross-linking time. The prepared hydrogels were characterized with respect to their structural, morphological, and some physical properties. The hydrogels ability to load high amounts of water-soluble drugs indicates their potential use as carriers for biologically active principles in the human body. A neural network methodology was applied to model the swelling degree and caffeine loading/release capacity depending on reaction conditions; in addition, applying this method, the optimal preparation conditions have been determined, targeting pre-established values for swelling degree or maximum caffeine value. The accuracy of the results obtained through this technique proves that the neural networks are suitable tools for modeling cross-linking processes taking place complex nonlinear polymers.
authors.affiliation: Technical University Gheorghe Asachi, Faculty of Chemical Engineering and Environmental Protection, Department of Natural and Synthetic Polymers, Iasi, Romania.
authors.forename: Anca N
authors.initials: AN
authors.lastname: Jătariu Cadinoiu
authors.forename: Marcel
authors.initials: M
authors.lastname: Popa
authors.forename: Silvia
authors.initials: S
authors.lastname: Curteanu
authors.forename: Cătălina A
authors.initials: CA
authors.lastname: Peptu
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002110:Caffeine / Q000008:administration & dosage; D048271:Chitosan / Q000737:chemistry*; D003198:Computer Simulation; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008956:Models, Chemical
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D004337:Drug Carriers; D020100:Hydrogels; D007477:Ions; D002110:Caffeine; D005780:Gelatin; D048271:Chitosan