A signal-off photoelectrochemical sandwich-type immunosensor based on WO3/TiO2 Z-scheme heterojunction

• Published in: Mikrochimica acta (1966) Vol. 190; no. 10; p. 384
• Main Authors: Pei, Fubin, Feng, Shasha, Hu, Wei, Hao, Qingli, Liu, Bing, Mu, Xihui, Lei, Wu, Tong, Zhaoyang
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.10.2023; Springer Nature B.V
• Subjects: Analytical Chemistry; Antibodies; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Electron paramagnetic resonance; Electron spin; Electrons; Gold; Heterojunctions; Immunosensors; Labels; Microengineering; Microspheres; Nanochemistry; Nanoparticles; Nanotechnology; Open circuit voltage; Original Paper; Photoelectric effect; Photoelectricity; Spin resonance; Titanium dioxide; Titanium oxides; Tungsten oxides; WO; TiO; Z-scheme heterojunction; Sandwich-type PEC immunosensor; Cs@Au NPs
• ISSN: 0026-3672; 1436-5073; 1436-5073
• DOI: 10.1007/s00604-023-05954-1

A sandwich “signal-off” type photoelectrochemical (PEC) immunosensor was fabricated based on a composite heterojunction of tungsten oxide/titanium oxide microspheres (WO 3 /TiO 2 ) acting as signal amplification platform and carbon microspheres loaded by gold nanoparticles (Cs@Au NPs) utilized as the label for detecting antibody. WO 3 /TiO 2 had excellent photoelectric performance, and the results of Mott-Schottky plots, open-circuit voltage, and electron spin resonance spectroscopy indicated that it belonged to the Z-scheme heterojunction transfer mechanism of photogenerated carriers. To achieve the sensitization of PEC immunosensor, Cs@Au NP–labeled immunocomplex can effectively reduce the photocurrent signal. The PEC immunosensors were fabricated under the optimal conditions of 1:1 WO 3 /TiO 2 (molar ratio), 2.0 mg mL −1 WO 3 /TiO 2 , and 1.5 mg mL −1 Cs@Au NPs. Through comparison of the detection results of label-free and sandwich-type PEC immunosensors for nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we found that the sensitivity of the sandwich type was 2.53 times the label-free type, and the limit of detection was 0.006 ng mL −1 , i.e., 3.17 times lower than the label-free type. This demonstrates that the developed sandwich-type PEC immunosensor will have a brighter application prospect. Graphical Abstract