Selectivity optimization of real-time and continuous sensing of endogenous H₂S in biological fluids

In the direct electrochemical sensing of endogenous hydrogen sulfide, the utilization of triple-pulse amperometry (TPA) enables the delivery of distinct cleaning and measurement pulses, effectively mitigating electrode surface passivation due to sulfur deposition. In order to further improve the sensor's sensitivity and selectivity, gold nanoparticles(nano-Au), platinum nanoparticles (nano-Pt), and poly(3,4-ethylenedioxythiophene) (PEDOT) were separately employed to modify electrodes for constructing electrochemical sensors. Their performance in detecting hydrogen sulfide was evaluated using constant potential amperometry (CPA) alongside TPA. Selectivity coefficients were determined based on current responses to hydrogen sulfide as well as four major interfering substances: ascorbic acid (AA), dopamine (DA), uric acid (UA), and epinephrine (EP). After quantitative comparison, the optimal solution for direct electrochemical sensing of hydrogen sulfide involved employing a PEDOT/nano-Au composite film in conjunction with TPA technology. The sensor responds to hydrogen sulfide in the concentration range 3.0-24.0 µM with a detection limit of 0.035 µM. Furthermore, the sensor demonstrates excellent repeatability and stability, rendering it suitable for continuous electrochemical monitoring of hydrogen sulfide in simulated real biological environments.