Combining Aptamers And Antibodies: Lateral Flow Quantification For Thrombin And Interleukin-6 With Smartphone Readout

Modern strategies in precision medicine require diagnostic tools for fast assessment of biomarkers. A popular and well-established assay format for the rapid detection of disease markers directly at the point of care is the lateral flow assay, which enables medical staff to directly use body fluids such as blood or urine for diagnosis, without the need for a professional laboratory environment. Interleukin-6 and thrombin are clinically relevant biomarkers that are associated with infectious diseases, inflammation, and blood coagulation, and can provide valuable information on the status and treatment responses of patients with COVID-19. This work presents a novel method for the quantification of these biomarkers by using fluorescent green and red quantum dots as labels for interleukin-6 antibodies and thrombin binding aptamers, respectively. For readout, a 3D printed smartphone imager with a built in UV-LED light source is used. Through separation of RGB-channels, the acquired images can be processed to achieve a fully functional duplex lateral flow assay for simultaneous quantification of interleukin-6 and thrombin on the same test line (optical multiplexing). Furthermore, the assay performs well in complex samples (10 % serum samples). In conclusion, this novel combination of antibody and aptamer-based detection in a single lateral flow assay reduces turnaround time, and the user-friendly smartphone imager facilitates availability, particularly in low resource settings.