Photoelectrochemical detection of tumor markers based on a CdS quantum dot/ZnO nanorod/Au@Pt-paper electrode 3D origami immunodevice

Abstract

A 3D origami photoelectrochemical (PEC) immunodevice based on CdS quantum dot (QD)-sensitized ZnO nanorods (ZNRs) as a photoactive matrix and glucose oxidase (GOx) functionalized nanoporous silver (NPS) as a label was established for sensitive detection of tumor markers. The ZNRs were grown on a porous Au@Pt core–shell nanoparticle modified paper working electrode (Au@Pt-PWE) via an in situ growth method. The coupling of CdS QDs and the ZNR/Au@Pt-PWE resulted in an enhanced excitation and photo-to-electric conversion efficiency. The large amount of GOx loading on the NPS in situ generated more H₂O₂ in the glucose substrate for electron donation, which amplified the photocurrent signals. And the good biocompatibility of the Au@Pt-PWE retained good stability for the sandwich-type immunoassay. A 3D origami photoelectrochemical immunodevice for the detection of carcinoembryonic antigen (CEA) and α-fetoprotein (AFP) was successfully developed with linear ranges of over 4 orders of magnitude and with detection limits down to 0.3 pg mL⁻¹ and 0.5 pg mL⁻¹. This proposed amplification strategy exhibited excellent stability and reproducibility in real human serum assay, and could be applied in point-of-care testing of other cancer markers.