Photoelectrocatalytic detection of NADH on n-type silicon semiconductors facilitated by carbon nanotube fibers

TL;DR

This study presents a photoelectrochemical biosensor using n-type silicon and carbon nanotube fibers for sensitive NADH detection, enabling low-potential measurements upon light irradiation.

Contribution

It introduces a novel photoelectrode combining silicon and carbon nanotubes for NADH quantification with high sensitivity and selectivity.

Findings

Linear response to NADH from 50 μM to 1.6 mM

High sensitivity of 54 μA cm$^{-2}$ mM$^{-1}$

Effective suppression of background signals

Abstract

NADH is a key biomolecule involved in many biocatalytic processes as cofactor and its quantification can be correlated to specific enzymatic activity. Many efforts have been taken to obtain clean electrochemical signals related to NADH presence and lower its redox overpotential to avoid interferences. Suppression of background and secondary signals can be achieved by including a switchable electroactive surface, for instance, by using semiconductors able to harvest light energy and drive the excited electrons only when irradiated. Here we present the combination of a n-type Si semiconductor with fibers made of carbon nanotubes as electroactive surface for NADH quantification at low potentials only upon irradiation. The resulting photoelectrode responded linearly to NADH concentrations from 50 {\mu} M to 1.6 mM with high sensitivity (54 $\mu$ A cm$^{-2}$ mM${-1}$). This system may serve as a biosensing platform for detection and quantification of dehydrogenases activity.