InGaN/GaN nanowires as a new platform for photoelectrochemical sensors - detection of NADH

InGaN/GaN nanowire heterostructures are presented as nanophotonic probes for the light-triggered photoelectrochemical detection of NADH. We demonstrate that photogenerated electron-hole pairs give rise to a stable anodic photocurrent whose potential- and pH-dependences exhibit broad applicability. In addition, the simultaneous measurement of the photoluminescence provides an additional tool for the analysis and evaluation of light-triggered reaction processes at the nanostructured interface. InGaN/GaN nanowire ensembles can be excited over a wide wavelength range, which avoids interferences of the photoelectrochemical response by absorption properties of the compounds to be analyzed by adjusting the excitation wavelength. The photocurrent of the nanostructures shows an NADH-dependent magnitude. The anodic current increases with rising analyte concentration in a range from 5µM to 10mM, at a comparatively low potential of 0mV vs. Ag/AgCl. Here, the InGaN/GaN nanowires reach high sensitivities of up to 91µAmM^-1cm^-2 (in the linear range) and provide a good reusability for repetitive NADH detection. These results demonstrate the potential of InGaN/GaN nanowire heterostructures for the defined conversion of this analyte paving the way for the realization of light-switchable sensors for the analyte or biosensors by combination with NADH producing enzymes.