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.

POSS/gelatin‐polyglutamic acid hydrogel composites: Preparation, biological and mechanical characterization

“…No statistically significant changes were observed when the pH of the equilibrating buffer solution changed from 7.4 to 10. According to the literature, in neutral and alkaline conditions, carboxylate anions coming from protein chains and residual polyglutammic acid determine electrostatic repulsion allowing the aqueous solution to get inside the network 29…”

Efficacy of sonically, ultrasonically and laser‐activated irrigation in removing a biofilm‐mimicking hydrogel from an isthmus model

“…The hydrogel was fabricated by dissolving 3 g of gelatine (Merck, Whitehouse Station, NJ, USA) and 0.03 g of hyaluronan (sodium hyaluronate 95%; Fisher, Waltham, MA, USA) in 22.5 mL of deionized water at 50 °C (Jătariu Cadinoiu et al . ), with addition of a red dye and hollow glass spheres (0.1 g; average diameter of 10 μm, density 1100 kg m − ³; Sigma Aldrich, Bornem, Belgium). The hydrogel was mixed with dentine debris in a 70/30 ratio (w/w), to obtain a more viscous substance, resembling hard tissue debris accumulation in the isthmus during canal preparation.…”

Localized removal of layers of metal, polymer, or biomaterial by ultrasound cavitation bubbles

“…A biofilm was mimicked with a hydrogel, created by dissolving 1 g gelatin (Merck, Whitehouse Station, NJ, USA), 0.02 g hyaluronan (sodium hyaluronate 95%, Fisher, Waltham, MA, USA), and 0.1 g red food color (KTC, Wednesbury, UK) in 45 ml warm water. 40 Hollow glass spheres with a mean diameter of 10 lm (Sphericel, Potters Industries, South Yorkshire, UK) were added as tracer particles. The final density of the hydrogel was 1:07ð60:07Þ Á 10 3 kg=m 3 .…”