question: 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 are lateral flow assays, which enable medical staff to directly use body fluids like blood or urine for diagnosis, without the need of a professional laboratory environment Interleukin-6 and thrombin are both clinically relevant biomarkers associated with infectious diseases, inflammation, and blood coagulation thus providing also valuable information on status and treatment-response of COVID-19 patients This work presents a novel method for the quantification of these biomarkers based on 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 was used Through separation of RGB-channels the acquired images can be processed to compose 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 while the use of our easy to compose smartphone imager ensures availability especially for low resource settings