Dual-Channel Photoelectrochemical Ratiometric Aptasensor with up-Converting Nanocrystals Using Spatial-Resolved Technique on Homemade 3D Printed Device

A near-infrared light-activated ratiometric photoelectrochemical aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF₄:Yb,Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A₁) and capture DNA (CA) were modified onto two working photoelectrodes (WP₁ and WP₂) through covalent binding, respectively, and then gold nanoparticle-labeled CEA aptamer 2 (Au NP-A₂) was immobilized on the surface of functional WP₂ for the formation of double-stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP₁, whereas the binding of the CEA with Au NP-A₂ could be released from the WP₂ thanks to the highly affinity of CEA toward A₂. The dual signal readout with the "signal-off" of WP₁ and "signal-on" of WP₂ were employed for the spatial-resolved PEC (SR-PEC) strategy to detect CEA as an analytical model. Combining NaYF₄:Yb,Er UCNPs@CdTe nanocrystals with spatial-resolved model on 3D printing device, the PEC ratiometric aptasensor based on steric hindrance effect and exciton-plasmon interactions (EPI) exhibited a linear range from 10.0 pg mL^-1 to 5.0 ng mL^-1 with a limit of detection of 4.8 pg mL^-1 under 980 nm illumination. The SR-PEC ratiometric strategy showed acceptable stability and reproducibility with a superior anti-interference ability. This approach can provide the guidance for the design of ratiometric, multiplexed, and point-of-care biosensors.