Chitosan functionalization of titanium and Ti6Al4V alloy with chloroacetic acid as linker agent.

In this work, a new covalent grafting of chitosan on titanium and Ti6Al4V alloy surfaces is reported using chloroacetic acid as linker agent. Good results were obtained both on titanium and on Ti6Al4V alloy. The effect of the surface acid pretreatments on the subsequent functionalization with chitosan is evaluated. The morphological aspect of acid etched metal surfaces before chitosan grafting has been characterized by scanning electron microscopy (SEM). The presence of carboxylic groups on metal surfaces and then the efficiency of chitosan covalent immobilization were detected by Fourier transformed infrared-Attenuated Total Reflectance (FTIR-ATR) and X-Ray photoelectron spectroscopy (XPS). Cyclic voltammetry tests, using the functionalized titanium and Ti6Al4V samples as electrodes, were conducted in different aqueous solutions, to detect the presence of the homogeneous overlayer of chitosan on the surface, and to evaluate the importance of the carboxyl groups as linker agent.

Functionalization of poly(ε-caprolactone) surface with lactose-modified chitosan via alkaline hydrolysis: ToF-SIMS characterization.

Functionalization of poly(ε-caprolactone) (PCL) was performed via hydrolysis and subsequent grafting of lactose-modified chitosan (chitlac) at two different degrees of derivatization (9% and 64%). Time of flight secondary ion mass spectrometry (ToF-SIMS) and multivariate analysis (principal component analysis) were successfully applied to the characterization of PCL surface chemistry, evidencing changes in the biopolymer surface following base-catalyzed hydrolysis treatment. ToF-SIMS analysis also confirmed positive EDC/NHS-catalyzed (EDC: N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide; NHS: N-hydroxysuccinimide) immobilization of chitlac onto activated PCL surface, with formation of amide bonds between PCL surface carboxyl groups and amine residues of chitlac. Yield of grafting reaction was also shown to be dependent upon the lactosilation degree of chitlac.