Light-addressable photoelectrochemical Immunosensing of neuron-specific enolase using Bi2O3/Bi2S3/Ag2S Nanodendrites on a single ITO electrode

In this work, a sensitive and reliable photoelectrochemical (PEC) sensor array integrated on a single electrode was developed for the spatially addressable detection of neuron-specific enolase (NSE), using Bi 2 O 3 /Bi 2 S 3 /Ag 2 S nanodendrites as the substrate electrode material. The Bi 2 O 3 /Bi 2 S 3 structure was grown in situ on an indium tin oxide (ITO) electrode to form large-area nanoarrays, whose uniform distribution helps minimize performance variations across different regions and enables light-addressable detection. Furthermore, Ag 2 S, a narrow-bandgap semiconductor with excellent photoelectric properties, was incorporated into the Bi 2 O 3 /Bi 2 S 3 system to enhance the photoelectrochemical response. The resulting Bi 2 O 3 /Bi 2 S 3 /Ag 2 S-modified ITO electrode was partitioned into five independent regions using insulating stickers, allowing addressable and continuous detection of multiple samples. Since the entire sensor array was fabricated in a single preparation step, inter-regional variability was significantly reduced, enabling the application of a self-calibration strategy to further improve sensitivity and accuracy. Under optimal conditions, the PEC sensor array detected NSE over a concentration range of 0.01–100 ng/mL, with a detection limit of 2.0 pg/mL (S/N = 3). The sensor also exhibited high selectivity, stability, and reproducibility, demonstrating its strong potential for real-sample applications.