Synthesis and characterization of chitosan membranes functionalized with amino acids and copper for adsorption of endoglucanase

Chitosan membranes were obtained and functionalized with amino acids and copper in order to improve adsorption selectivity of endoglucanase. The membranes were characterized by Fourier-transformed infrared spectroscopy with attenuated total reflectance device (FTIR-ATR) to monitor chemical changes. Scanning electron microscopy (SEM) was performed to compare the surface morphology of the membranes. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were carried out in order to analyze thermal stability of functionalized membranes and to identify the differences between functionalized chitosan membranes before and after endoglucanase adsorption. SEM results proved that functionalization had occurred since the surface of the chitosan membrane was modified. FTIR-ATR results confirmed an effective chemical modification of chitosan membranes with amino acids and copper and corroborated endoglucanase adsorption. The characteristic parameters of DSC and TGA also evidenced endoglucanase adsorption. The use of functionalized membranes as adsorbents increased 40-fold the percentage of endoglucanase adsorption as compared to unmodified membranes. Thus, chitosan membranes functionalized with amino acids and copper may represent a novel, low-cost adsorbent to be used in endoglucanase purification from complex systems.