Functionalized Quantum Dot-Based Portable Sensor for Dual Detection of Stress Biomarkers in Blood Serum and Saliva

This work reports on the simultaneous detection of cellular stress biomarkers in blood and saliva, using a portable sensor. We expanded the application of our optical measurement system, the Transilluminated Quantum Dot (TIQD) imager, paired with a low-cost biochip for minimally invasive biomolecule detection. Streptavidin functionalized quantum dots (Sav-QDs) were conjugated with biotinylated antibodies (Ab) against stress biomarkers heat shock protein (Hsp). The presence of biomarkers in biological samples was indicated by the fluorescence masking of Sav-QDs, based on their binding to the Abs conjugated to Sav-QDs, resulting in reduced fluorescence. The decrease in fluorescence directly correlates with biomarker concentration. We have successfully detected Hsp90 and Hsp70 spiked in artificial blood serum. The limit of detection (LoD) was around 50 nM for Hsp90 and 96 nM for Hsp70. Our portable sensor addresses the need for reliable point-of-care (PoC) stress diagnosis by enabling robust, multiple biomarkers detection in diverse biological samples.