An ultrasensitive alloyed near-infrared quinternary quantum dot-molecular beacon nanodiagnostic bioprobe for influenza virus RNA.

Conventional techniques used to diagnose influenza virus face several challenges, such as low sensitivity, slow detection, false positive results and misinterpreted data. Hence, diagnostic probes that can offer robust detection qualities, such as high sensitivity, rapid detection, elimination of false positive data, and specificity for influenza virus, are urgently needed. The near-infrared (NIR) range is an attractive spectral window due to low photon absorption by biological tissues, hence well-constructed fluorescent biosensors that emit within the NIR window can offer an improved limit of detection (LOD). Here, we demonstrate the use of a newly synthesized NIR quinternary alloyed CdZnSeTeS quantum dots (QDs) as an ultrasensitive fluorescence reporter in a conjugated molecular beacon (MB) assay to detect extremely low concentrations of influenza virus H1N1 RNA. Under optimum conditions, two different strains of influenza virus H1N1 RNA were detected based on fluorescence enhancement signal transduction. We successfully discriminated between two different strains of influenza virus H1N1 RNA based on the number of complementary nucleotide base pairs of the MB to the target RNA sequence. The merits of our bioprobe system are rapid detection, high sensitivity (detects H1N1 viral RNA down to 2 copies/mL), specificity and versatility (detects H1N1 viral RNA in human serum). For comparison, a conventional CdSe/ZnS-MB probe could not detect the extremely low concentrations of H1N1 viral RNA detected by our NIR alloyed CdZnSeTeS-MB probe. Our bioprobe detection system produced a LOD as low as ~1 copy/mL and is more sensitive than conventional molecular tests and rapid influenza detection tests (RIDTS) probes.