Voltage-programmable biofunctionality in MEMS environments using electrodeposition of a reactive polysaccharide

The amino-polysaccharide chitosan has distinct properties that make it an attractive interface material for the assembly of biomolecules onto microfabricated surfaces. Chitosan has pH-responsive electrostatic and solubility properties that allow it to be deposited and retained on cathode surfaces. Deposition is shown to be spatially controllable at /spl mu/m levels by "templating" the chitosan onto micropatterned gold cathodes. Temporal control of deposition can be achieved depending on when the micropatterned electrodes are polarized. Chitosan also has nucleophilic amine groups that can be easily reacted using standard, amine-specific chemistries. Studies show that the sequence of chitosan deposition and chemical modification is repeatable. Finally, standard chemistries can be exploited to couple biomolecules onto chitosan films that have been "templated" onto the micropatterned gold cathodes. Specifically, we used glutaraldehyde activation to assemble the model protein, green fluorescent protein (GFP) onto a chitosan deposit. These studies demonstrate that chitosan has unique properties that allow it to serve as an interface material for the assembly of biomolecules onto microfabricated surfaces.