Assesment of the suitability of xylan/chitosan based hydrogels for potential biomedical applications

M.V. GALVÁN; G.E. RAMELLA; C. N. SCHNELL; M. A. ZANUTTINI.; P. MOCCHIUTTI

Espoo

Congreso; Congreso Iberamericano de Investigación en Celulosa y Papel (CIADICYP).; 2016

CIADICYP

Hydrogels have had growing interest in medical and industrial applications, such as in transdermal drug delivery system. They are defined as cross-linked polymer networks that have the ability to swell without dissolving in water. Particularly, natural hydrogels have the advantages of being ecological, biocompatible and biodegradable. In this work, hydrogels were obtained from natural polyelectrolyte complexes (PECs) containing high amount of xylan (Xyl) and chitosan (Ch) (70 wt% Xyl / 30 wt% Ch). To improve the performance of them, citric acid/sodium citrate was used as a non-toxic cross-linking agent. Hydrogels were prepared by casting/evaporation the suspensions of PECs (at pH 5.0 and low ionic strength), washed in water to eliminate salts, and dried again. When the cross-linked agent was added, the washed films were then immersed in citric acid/sodium citrate (from 1% w/v to 7 %w/v) for 1 h and 4°C, and washed again. All films were characterized by using Fourier transform infrared (FTIR) spectroscopy. It was found that the spectra have clearly changed in the region 1400-1724 cm-1 when the crosslinking agent was added, indicating the effective ionic interaction between the chitosan and sodium citrate. The swelling capacity and solubility of the hydrogels were determined by immersing them in a phosphate buffer saline (PBS) solution at pH 7.4 and up to 24 h. The swelling of the non cross-linked hydrogel was up to 220%, while cross-linked hydrogels showed even higher results. On the other hand, solubility also increased, but only up to 20%. The higher the amounts of cross-linked agent, the higher were the wet mechanical properties. Cross-linked Xyl/Ch hydrogels have about 150% higher wet-stress at break, and 100% higher wet-strain at break than non cross-linked hydrogels. Finally, the rate of diclofenac sodium drug release from hydrogels was performed by immersing them in PBS solution and incubating on a shaking water-bath at 37°C. At different time intervals, an aliquot of PBS was withdrawn and the amount of drug was determined by measuring at 275 nm in a UV?vis spectrophotometer. It was found that the drug was absorbed on the hydrogels and gradually released it up to 48 h. It can be concluded that biodegradable hydrogels based on xylan and chitosan cross-linked with sodium citrate are an interesting alternative for potential biomedical applications.