Dual amplification for PEC ultrasensitive aptasensing of biomarker HER-2 based on Z-scheme UiO-66/CdIn2S4 heterojunction and flower-like PtPdCu nanozyme.

As an important prognostic indicator in breast cancer, human epithelial growth factor receptor-2 (HER-2) is of importance for assessing prognosis of breast cancer patients, whose accurate and facile analysis are imperative in clinical diagnosis and treatment. Herein, photoactive Z-scheme UiO-66/CdIn2S4 heterojunction was constructed by a hydrothermal method, whose optical property and photoactivity were critically investigated by a range of techniques, combined by elucidating the interfacial charge transfer mechanism. Meanwhile, PtPdCu nanoflowers (NFs) were fabricated by a simple aqueous wet-chemical method, whose peroxidase (POD)-mimicking catalytic activity was scrutinized by representative tetramethylbenzidine (TMB) oxidation in H2O2 system. Taken together, the UiO-66/CdIn2S4 based photoelectrochemical (PEC) aptasensor was established for quantitative analysis of HER-2, where the detection signals were further magnified through catalytic precipitation reaction towards 4-chloro-1-naphthol (4-CN) oxidation (assisted by the PtPdCu NFs nanozyme). The PEC aptasensor presented a broader linear range within 0.1 pg mL-1-0.1 µg mL-1 and a lower limit of detection of 0.07 pg mL-1. This work developed a new PEC aptasensor for ultrasensitive determination of HER-2, holding substantial promise for clinical diagnostics.

Integration of CuS/ZnIn2S4 flower-like heterojunctions and (MnCo)Fe2O4 nanozyme for signal amplification and their application to ultrasensitive PEC aptasensing of cancer biomarker.

Vascular endothelial growth factor 165 (VEGF165) is a crucial regulator of angiogenesis and works as a major protein biomarker of cancer metastasis. Therefore, its quantitative detection is pivotal in clinic. In this work, CuS/ZnIn2S4 flower-like heterojunctions had strong and stable photocurrents, which behaved as photoactive material to construct a photoelectrochemical (PEC) aptasensor for detecting VEGF165, combined by home-prepared (MnCo)Fe2O4 nanozyme-mediated signal amplification. The interfacial photo-induced electron transfer mechanism was chiefly discussed by UV-vis diffuse reflectance spectroscopy in details. Specifically, the (MnCo)Fe2O4 modified VEGF165 aptamer was released from the PEC aptasensing platform for its highly specific affinity to target VEGF165, which terminated the color precipitation reaction, ultimately recovering the PEC signals. The developed sensor displayed a wider linear range from 1 × 10-2 to 1 × 104 pg mL-1 with a smaller limit of detection (LOD) of 0.1 fg mL-1. This study provides some valuable insights for building other ultrasensitive aptasensors for clinical assays of cancer biomarkers in practice.