Coupling Self-Assembly Mechanisms to Fabricate Molecularly and Electrically Responsive Films.

Biomacromolecules often possess information to self-assemble through low energy competing interactions which can make self-assembly responsive to environmental cues and can also confer dynamic properties. Here we coupled self-assembling systems to create biofunctional multilayer films that can be cued to dis-assemble through either molecular or electrical signals.  To create functional multi-layers we: (i) electrodeposited the pH-responsive self-assembling aminopolysaccharide chitosan; (ii) allowed the lectin Concanavalin A (ConA) to bind to the chitosan-coated electrode (presumably through electrostatic interactions); (iii) performed layer-by-layer self-assembly by sequential contacting with glycogen and ConA; and (iv) conferred biological (i.e., enzymatic) function by assembling glycoprotein (i.e., enzymes) to the ConA-terminated multilayer.  Because the ConA tetramer dissociates at low pH, this multilayer can be triggered to dis-assemble by acidification.  We demonstrate two approaches to induce acidification: (i) glucose oxidase can induce multilayer dis-assembly in response to molecular cues; and (ii) anodic reactions can induce multilayer dis-assembly in response to electrical cues.