Sensitive detection of ascorbic acid and alkaline phosphatase activity by double-channel photoelectrochemical detection design based on g-C3N4/TiO2 nanotubes hybrid film

• Double-channel detection approach was design to improve the stability in photoelectrochemical sensor.
• The inner resistance of photoelectrochemical sensor was measuring in a two-electrode system.
• The interference from matrix effect was eliminated efficiently by the differential measurement strategy.

This work developed a simple double-channel detection approach to improve the stability and credibility in photoelectrochemical (PEC) sensors. The working principle is based on differential signal between the measuring and reference PEC cells. This measurement approach offers the advantage over established single-channel PEC mode in that the effect of the drift in the intensity of excitation source is diminished owing to the differentiating nature of the system, leading to better signal-to-noise ratio and hence higher measurement sensitivity. Additionally, the differential measurement scheme reduced the interference from matrix effect. Sensitive detection of ascorbic acid and alkaline phosphatase activity by the differential PEC mode based on g-C3N4/TiO2 nanotube array hybrid film was demonstrated. The as-prepared PEC sensor offeres signal-enhancement response to ascorbic acid in a concentration variation from 1 nM to 10 μM with a detection limit of 0.3 nM. The determination the activity of alkaline phosphatase in serum samples enabled a quantification range of 0.3 mU/L–1 U/L with a detection limit of 0.1 mU/L.

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