A "signal-on" photoelectrochemical sensor based on hierarchical titanium dioxide nanowires/microflowers decorated graphite-like carbon nitride quantum dots for glutathione detection

Glutathione (GSH) is a bioactive tripeptide with important physiological functions in animals, plants, and microorganisms. GSH participates in various biochemical reactions in vivo and is known for its antioxidant, anti-allergy, and detoxification properties. This study introduces an innovative photoelectrochemical (PEC) method for GSH detection, leveraging a fluorine-doped tin oxide (FTO) electrode enhanced by TiO₂ nanoflowers and graphitic carbon nitride quantum dots (g-CNQDs). This design formed a type-II heterojunction, which facilitated efficient charge separation and transport. Furthermore, incorporating TiO₂ nanoflowers increases the surface area, while adding g-CNQDs led to a narrowing of the semiconductor bandgap. The fabricated electrode exhibits highly attractive photo-electrocatalytic activity towards GSH detection in neutral media at a low potential bias. The developed PEC sensor demonstrates a wide linear range of 1.0 × 10^-13 to 5 × 10^-5 mol L^-1, a low detection limit of 5.0 fmol L^-1, and high sensitivity. These remarkable analytical characteristics highlight the potential of this PEC platform for sensitive and selective GSH detection in various biomedical and environmental applications.