Adsorption and Desorption Behaviors of Bovine Serum Albumin on Gelatin/Chitosan Sponge

Abstract

Gelatin (Gel) and chitosan (CTS) have several biomedical applications because of their biodegradability and biocompatibility. Crosslinking of Gel and Gel/CTS systems was evaluated using N-acetyl-D-glucosamine (GlcNAc) formed into sponges by lyophilization. The prepared sponges were used to study the adsorption and desorption of fluorescein isothiocyanate (FITC) labeled bovine serum albumin (BSA) as a model instead of a growth factor. The effect of FITC-BSA concentration and temperature on the adsorption behavior of Gel/CTS sponges was investigated. The Langmuir adsorption isotherm model was used on the basis of the assumption that monolayer adsorption occurs on the surface; the results fit with the experiment data. The adsorption constants were 5.77 and 9.68 mL/mg for Gel and Gel/CTS sponges, respectively. The adsorption thermodynamic constants were found; adsorption onto sponges was an exothermic reaction. In particular, Gibbs free energy (ΔG) exhibited negative values in the range of 283 - 343 K for both Gel and Gel/CTS sponges, demonstrating the spontaneous nature of adsorption reaction. In addition, desorption behavior was evaluated for different concentrations and pH values of the FITC-BSA solution. The high adsorbed amounts of FITC-BSA on sponge resulted in high desorbed amounts in sponge, up to 55% from 3.5 mg/mL adsorbed concentration (around 1.5 mg from 3 mg adsorb amount). Desorption decreased following the buffer solution pH decrease, from 7.4 to 4 and 2 in Gel and Gel/CTS sponges, respectively. Based on the results of this preliminary study, these composite sponges could have significant application in biomedical materials.