Detection of Photosystem I Reaction Centers using Chemically Derivatized High Electron Mobility Transistor

This paper presents for the first time a micro-sensor for detecting Photosystem I (PS I) reaction centers. In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers, Photosystems I and II (PS I and PS II). Photon capture triggers rapid charge separation and the conversion of light energy into an electric voltage across the nanometer-scale (~6 nm) reaction centers. AlGaN/GaN based high electron mobility transistors (HEMTs) show high current throughputs and greater sensitivity to surface charges. PS I molecules were chemically immobilized on the HEMT device and significant changes in the transistor characteristics were noticed. With zero gate bias and 5 V at drain terminal, drain current changes by about 5 mA for 6muL drop of PS I solution. The difference between light and dark measurements is ~0.8 mA. Test results demonstrate that this approach is a potential candidate for detection and characterization of biomolecular photodiodes -PS I reaction centers.