Ratiometric upconversion-luminescence in-situ sampling aptasensing platform integrated with smartphone-based device for visual detection of 17β-estradiol

Rapid initial screening of health markers and food hazards are crucial indicators for ensuring human well-being. Hence, an upconversion-luminescence based aptasensing platform for the in-situ sampling of hazards has been proposed with portable equipment for point-of-care testing (POCT). The aptasensing platform consists of a polymethylmethacrylate needle and a paper-based microfluidic strip patterned with a sacrificial valve, paraffin barriers, and three independent detection zones. The detection zones were assembled with a luminescence resonance energy transfer system constructed by the core/shell/shell structure of upconversion nanoparticles (UCNPs) as the donor, SYBR Green Ⅰ as the acceptor with an aptamer bridge. The biosensing platform has been extended for 17β-estradiol to validate its feasibility in a dual-mode signal readout system based on smartphone imaging and spectrometer. Under the optimal conditions, good linear relationships were achieved based on images (0.05–200 ng/mL) and ratiometric spectra (0.02–200 ng/mL), respectively. Thus, the biosensing platform with portable equipment might provide an economic and viable route for POCT.