Mechanism and Direct Visualization of Electrodeposition of the Polysaccharide Chitosan

Chitosan, a biocompatible and bioactive polysaccharide biopolymer that comes from the deacetylation of chitin, has attracted much attention recently due to its electro-responsive gelation property. Such a property allows chitosan hydrogel to be assembled from aqueous solution onto a cathode surface in response to an electrical signal. To in situ visualize and quantitatively characterize the electrodeposition of the chitosan hydrogel, we developed a unique transparent fluidic system with paired sidewall electrodes. Such a system allows us to demonstrate and directly measure the time dependent thickness and density of the deposited hydrogel. Based on the results, we explained the electrogelling mechanism and interpreted the dominant causes responsible for the formation and the density distribution of deposited chitosan hydrogel. This report provides important guidelines for pursuing applications of electrodeposited chitosan hydrogel in integrated biochips and bioelectronic devices.