Chitosan to electroaddress biological components in lab-on-a-chip devices

Chitosan offers a unique set of properties that suggest its potential for interfacing biological components into electronic devices for lab-on-a-chip (LOC) applications. Specifically, chitosan's pH-responsive film-forming properties allow it to be electrodeposited as a stable thin film in response to localized cathodic signals. In addition, the electrodeposited chitosan film can be electrochemically activated for protein conjugation by applying an anodic potential to the chitosan-coated electrode while it is immersed in an aqueous solution containing NaCl. Together electrodeposition and electrochemical protein conjugation allow proteins to be electroaddressed to electrode surfaces quickly and without the need for reactive reagents. On-going efforts aim to extend protein electroaddressing from patterned chips to microfluidic LOC devices. Additional efforts are beginning to show the potential for integrating chitosan with sensor technology to transduce chemical and biological events (e.g., molecular recognition) into device-compatible optical, electrical and mechanical signals. Highlights of the progress in using chitosan as the bio-device interface are reviewed.