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Proceedings Paper

Photoresponsive hydrogel microvalve activated by bacteriorhodopsin proton pumps
Author(s): Khaled Al-Aribe; George K. Knopf
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Paper Abstract

A light driven microvalve activated by a thin organic photoelectric film that controls the expansion and shrinkage of a pH sensitive HEMA-AA hydrogel actuator is described in this paper. The self-assembled monolayer of oriented bacteriorhodopsin (bR) purple membrane patches are immobilized on a porous bio-functionalized gold (Au) surface using a biotin molecular recognition technique. When exposed to visible light, each bR molecule in the monolayer acts as a simple proton pump which transports hydrogen ions from the cytoplasmic to the extracellular side through a transmembrane ion channel that connects both sides of the membrane. The flow of ions from the photon activated bR changes the pH value of the ionic solution that surrounds the gel microactuator. The chargeable polymeric network undergoes a measureable geometric change when the pH of the ionic solution is shifted to the phase transition point pKa. The fabrication of the thin bR film and photo-responsive hybrid hydrogel are discussed. Preliminary experiments show that the 13nm self-assembled photoelectric layer can generate approximately 1.3mV/(mW·cm2) when exposed to an 18mW, 568nm light source. The photo-voltage produced by the monolayer is believed to be sufficient to change the pH of the surrounding ionic solution from its neutral state and trigger the swelling of the gel. Several design issues that need to be resolved before a fully functional light-driven microvalve can be created are identified and discussed.

Paper Details

Date Published: 30 March 2010
PDF: 12 pages
Proc. SPIE 7646, Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2010, 764611 (30 March 2010); doi: 10.1117/12.848769
Show Author Affiliations
Khaled Al-Aribe, The Univ. of Western Ontario (Canada)
George K. Knopf, The Univ. of Western Ontario (Canada)

Published in SPIE Proceedings Vol. 7646:
Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2010
Vijay K. Varadan, Editor(s)

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