Characterization of Electrodeposited Chitosan Films by Atomic Force Microscopy and Raman Spectroscopy

Abstract

Chitosan has served as a robust and reproducible scaffold for biological reactions by electrodeposition at specific sites in microfluidic channels. However, its growth and properties are not well understood as a function of deposition parameters. To better understand the materials and process science, in-vitro characterization techniques and post-deposition measurements of air-dried films were performed. AFM images of dried films depicted variable, rough morphology not directly correlated to deposition conditions while hydration increased surface homogeneity. Dry roughness increased logarithmically with thickness supporting growth by nucleation. In-vitro fluorescence images showed fairly smooth distribution of chitosan, whereas dried films were much rougher, indicating non-uniform collapse of structure during drying. Raman spectroscopy revealed the presence of primary amine groups active in biofunctionalization and served as a technique for evaluating the spatial selectivity of chitosan by electrodeposition. Further study of hydrated films is needed to fully understand chitosan as a platform for biotechnology applications.