Specific oligonucleotide-modified QDs as a powerful platform for SARS Cov-2 virus detection by FRET-based biosensors

FRET-based nano-bioconjugate sensors (nano-biosensors) could be examined in coronavirus disease (COVID-19) diagnosis. In this work, a nano-biosensor for SARS Cov-2 virus detection was established based on fluorescence resonance energy transfer (FRET) between oligonucleotide-modified CdTe/ZnS quantum dots (QDs) as a donor and Cy3 as an acceptor. UV-visible spectrophotometry, FT-IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to characterize the chemical and physical structures of the nano-biosensor. Under optimized conditions, the detection limit of complementary target DNA (ctDNA) was 2.19 x 10(-9) mu M. The linear equation and regression were y = 181.8x + 1 and R-2 = 0.9762. In addition, capture DNA/QDs ratios were modified under different conditions. Finally, under optimal conditions, the feasibility of the current nano-biosensor evaluated for monitoring SARS Cov-2 in real samples.