Photoinduced Electron Transfer Modulated Photoelectric Signal: Toward an Organic Small Molecule-Based Photoelectrochemical Platform for Formaldehyde Detection

Photoelectrochemical (PEC) sensing has been rapidly evolvinginrecent years, while the introduction of small molecules with specificrecognition functions into the sensing interface remains a nascentarea of study. In this work, we reported a PEC biosensor for formaldehyde(FA) detection based on photoinduced electron transfer (PET)-gatedelectron injection between organic small molecules and inorganic semiconductingsubstrates. Specifically, an FA-responsive probe (NA-FA-COOH) andTiO(2) nanoarrays were integrated to construct a PEC platform(NFC/TiO2) via a coordination bond. NFC served simultaneouslyas a target-specific recognition element and a modulator of photoinducedelectron injection. Treatment of NFC/TiO2 by FA would suppressthe intramolecular PET process, with the quenched photocurrent signaldue to the changed carrier transfer pathway, thus establishing thePEC platform for FA based on effective PET modulation. The proposedPEC system exhibited high selectivity and sensitivity, with a lowdetection limit of 0.071 mu M. This study presents a novel perspectiveon the use of organic small molecules with a PET effect for advancedPEC bioanalysis.