In2O3/CdS heterojunction-based photoelectrochemical sensor for therapeutic drug monitoring of rifampicin in clinical samples.
Rapid and reliable determination of rifampicin (RIF) is important for dose optimization and therapeutic drug monitoring during tuberculosis treatment. Herein, In2O3/CdS heterojunctions were fabricated through calcination followed by in situ CdS growth and employed as an efficient photoactive interface for photoelectrochemical RIF sensing. The In2O3/CdS heterojunction enhanced photoinduced charge separation and provided an amplified photocurrent background, while RIF induced a concentration-dependent photocurrent quenching response for signal-off PEC quantification. Under optimized conditions, the proposed sensor showed a linear response to RIF over the concentration range of 0.010-75 μM, with a detection limit of 1.45 nM (S/N = 3). The sensor exhibited satisfactory selectivity against common coexisting substances, as well as good repeatability and storage stability. Accurate RIF quantification was further achieved in spiked human serum, urine, and pharmaceutical capsule samples, affording recoveries of 97.73% and 103.49% with relative standard deviations below 4.1%. This work provides a sensitive and reliable PEC platform for RIF determination in complex biological and pharmaceutical matrices.