2,3-Dihydroxynaphthalene invoked surface oxygen vacancy effect on Fe2O3 nanorods for photoanodic signal transduction tactic

The state-of-art signal transduction mechanism of anodic photoelectrochemistry is constrained to the hole oxidation reaction, which greatly hinders its application for prospective biosensing applications. Herein, we present an innovative strategy for signal transduction by exploiting the in situ formation of surface oxygen vacancies (VOs) on Fe2O3 nanorods (NRs) through the self-coordination of 2,3-dihydroxynaphthalene (2,3-DHN) on their surfaces. The 2,3-DHN was connected with Fe(III) on the surface of Fe2O3 NRs vis the formation of the fivemembered ring structures accompanied by the generation of VOs. And the generated VOs introduced a new defect energy level for trapping the photogenerated holes, which enhanced the charge separation and realized the enhancement of photocurrent signal. The developed signal transduction strategy was validated by the first photoelectrochemical (PEC) sensing platform for & beta;-glucoside (& beta;-Glu) and lipase (LPS), which can catalyze the hydrolysis of 3-hydroxy-2-naphthalenyl-& beta;-D-glucoside and naphthalene-2,3-diol diacetate, respectively, to produce 2,3-DHN for signal stimuli. The & beta;-Glu and LPS were detected with linear ranges of 0.01-10.0 U/mL and 0.001-5.0 mg/mL, respectively. Detection limits of 3.3 x 10-3 U/mL and 0.32 & mu;g/mL (S/N = 3) were achieved, for & beta;-Glu and LPS, respectively. The present study not only provides a new strategy for spontaneous induction of VOs in situ for n-type semiconductors, but also innovates the anodic PEC signal transduction strategy with broadened biosensing applications.