Addressable Label-Free Photoelectric Sensor Array with Self-Calibration for Detection of Neuron Specific Enolase

An addressable label-free photoelectric immunosensor array was designed for detection of neuron specific enolase (NSE) based on TiO₂/CdS as substrate materials. In this work, the hydrothermal synthesized TiO₂ nanorod film is evenly grown on the surface of the fluorine-doped tin oxide (FTO), and then CdS with a narrow band gap is added for sensitization through successive ionic layer adsorption reactions. The obtained TiO₂/CdS composite materials with matched energy band structures promote the rapid electron transfer and effectively reduce the recombination of electron hole pairs, which greatly enhance the visible light absorption and increased photocurrent intensity. In order to construct a suitable sensor array, the sensitized FTO electrode is divided into multiple regions of equal size by insulating stickers, and then the addressable and continuous detection of multiple samples can be achieved. Because multiple detection regions are prepared and tested under the same conditions, the difference effectively reduces, and the sensor can realize self-calibration and obtain more accurate results. Under optimal conditions, this sensor array can detect NSE in the linear range of 0.01-100 ng mL^-1 with a detection limit of 2.49 pg mL^-1 (S/N = 3). The sensor array has good selectivity, stability, and reproducibility, making it a viable approach for real sample detection.