Ultra-sensitive photoelectrochemical aptasensor based on a CdIn2S4/ZnSnO3 composite for the detection of adenosine triphosphate

Abstract

Adenosine triphosphate (ATP) is an important extracellular signaling molecule in the human body. Its abnormal expression is closely related to the occurrence and development of various diseases, and accurate detection is of great significance for early disease diagnosis. However, conventional photoelectrochemical (PEC) sensors still suffer from low visible-light utilization, serious recombination of photogenerated carriers and limited detection sensitivity, making it difficult to achieve accurate detection of low-abundance ATP. In this work, an enzyme-catalyzed PEC aptasensor based on a CdIn2S4/ZnSnO3 (CIS/ZSO) heterojunction was constructed. The heterojunction significantly enhances visible-light absorption and promotes the separation and transport of photogenerated carriers, with a photocurrent response approximately 10 times higher than that of pure CdIn2S4. In the presence of 3,3'-diaminobenzidine (DAB) and hydrogen peroxide (H2O2), the amino-functionalized MnFe2O4 (MnFe2O4-NH2) nanozyme with outstanding peroxidase-like activity catalyzes the production of insoluble ox-DAB precipitates. The precipitate hinders interfacial electron transfer via steric hindrance and decreases the photocurrent. With specific recognition of ATP, the amount of MnFe2O4-NH2 on the electrode surface was reduced, the photocurrent was recovered and a signal-on detection mode was achieved. The aptasensor exhibits a linear range from 10-12 to 10-7 g/mL with a detection limit of 0.33 pg/mL, together with satisfactory reproducibility, stability and practical applicability. This work provides a new strategy for the efficient detection of low-abundance biological small molecules and a new approach for early clinical monitoring and diagnosis of diseases.