Gelatin/nanocellulose hydrogels: A potential materials for biomedical applications.

ALDANA PIZZANOA; MELINA BRACONE; JIMENA GONZÁLEZ; MARÍA FERNANDA HORST; VERONICA LASSALLE; VERA ALVAREZ

Montevideo

Workshop; Workshop on Insights and Strategies Towards a Bio-Based Economy; 2016

Nanocellulose is an attractive emerging material for biomedical applications due to its renewable nature, anisotropic shape, excellent mechanical properties, and good biocompatibility, among others. It is possible find three types of materials: i) cellulose nanocrystals (CNs) or nanocrystalline cellulose or cellulose nanowhiskers, ii) cellulose nanofibrils, and iii) bacterial cellulose. Different approaches are used to extract nanoparticles from cellulose sources, resulting in particles with varied crystallinities, surface chemistries, and mechanical properties. Due to its chemical structure nanocellulose can interact with others components through: electrostatic interactions, hydrogen bonds or van der Waals interactions and/or uneven exposure of chemical functions on the crystal faces resulting in hydrophobic or hydrophilic in nature faces. Hydrogels are soft materials with high amount of water, they are ideal materials for many biomedical applications. In particular, gelatin hydrogels are biocompatible and non-toxic. However they lack in mechanical properties. In this context, nanocomposites have been introduced to improve mechanical stiffness and durability. Moreover, hydrogel composites with nanocellulose seems to be promising biomaterials. The main objective of this study is to synthetize gelatin based hydrogels modified with nanocellulose for biomedical applications. The nanocellulose was obtained from a commercial microcellulose (Sigma Aldrich). The gelatin/nanocellulose hydrogel was synthetized from freeze-thawing technique. In brief, an amount of gelatin and gum arabic (crosslinked agent) were dispersed in distilled water. The addition of aqueous dispersion of nanocellulose was performed and the mixture was allowed swell at 6°C during 24 h. Then, the temperature was increased to 50°C and maintained for an hour. After that, the solution was filled in disposable molds, allowing the formation of the hydrogel. Different amounts of nanocellulose content from 2 to 10% wt were evaluated. In this study cellulose nanowhiskers was obtained by ultrasonication in distilled water. The SEM images observed displayed average diameter of 37.50 ± 6.09 nm and 240 nm lengths. FTIR spectroscopy showed the stretching vibration of free ? OH at 3320 cm-1 and the stretching vibration of C-H at 2892 cm-1. Thermogravimetric measurements displayed a degradation temperature at 333 °C and the obtained nanocellulose have a crystallinity index, IC% of 64.95 (determined by DRX). The dispersion property of nanocellulose was tested in water, ethanol/water, acetone/water and acetone. Besides, the average diameter determined by Dynamic Light Scattering was measured in those three media. The values of hydrodynamic diameter in aqueous dispersion were broad in the range of 1-2 and the nanocellulose was not well dispersed. Moreover diameters around 800 nm were obtained in acetone/water dispersion. Meanwhile for acetone dispersion the hydrodynamic values were in the range of 500 nm. The later media was the better media where nanocellulose can disperse. Furthermore z potential measurements resulted in negative values for all the dispersions analyzed. The hydrogel synthetized is being characterized by FTIR, DRX, swelling, TGA and SEM. Finally the application perspective of the hydrogel is for wound dressing. For this adsorption of bovine serum albumin (BSA) as model protein has been selected.