Single-crystal gallium oxide-based biomolecular modified diode for nucleic acid sensing

A single-crystal gallium oxide (beta-Ga2O3) has been investigated for biosensing applications in the form of an electrolyte/ oxide diode. beta-Ga2O3, a transparent conducting oxide, has great potential to be used in upcoming bioelectronics technologies such as integrated biosensors. The surface of a beta-Ga2O3 substrate was silanized with 3-aminopropyl-triethoxysilane (APTES) and modified with N-succinimidyl-6-maleimidylhexanoate (EMCS) to immobilize the capture probe DNA (thiol-terminated single-stranded DNA). A bimolecular diode formed by interfacing electrolytes with this beta-Ga2O3 substrate can detect the increased threshold potential of the diode's forward bias current and the charge transfer resistivity resulting from the surface modification. The capture probe modified surface has been used for target detection, and complementary DNA sequences could be distinguished from noncomplementary DNA with a nearly twentyfold relative resistivity difference observed through the diode characteristics. The sensing mechanism and detection ability demonstrated indicate the feasibility of the development of Ga2O3-based integrated bioelectronics. (C) 2015 The Japan Society of Applied Physics