RESUMEN
SARS-CoV-2, a highly transmissible and mutagenic virus, made huge threats to global public health. The detection strategies, which are free from testing site requirements, and the reagents and instruments are portable, are vital for early screening and play a significant role in curbing the spread. This work proposed a silver-coated glass slide (SCGS)/DNA walker based on a dual targets-triggering mechanism, enzyme-catalyzed amplification, and smartphone data analysis, which build a portable visual detection strategy for the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) gene. By this method, the detection was reflected by the ultraviolet absorbance changes and visible color changes to the naked eye which was analyzed by Red-Green-Blue (RGB) data analysis via smartphone within 30 min, simplifying the detection process and shortening the detection time. Meanwhile, the dual targets-triggering mechanism and dual signal amplification strategy ensured detection specificity and sensitivity. Further, the practicability was verified by the detection of the real sample which provided this method an application potential in SARS-CoV-2 rapid detection.
RESUMEN
A method is described for fluorometric determination of platelet-derived growth factor BB (PDGF-BB) and avian influenza A (H1N1) virus DNA. It is based on the use of the hybridization chain reaction (HCR) and of glucose oxidase (GOx) assisted dual-recycling amplification. A silver coated glass slide (SCGS) serves as an ideal material for separation. A signal DNA/initiator triggers the HCR and generates a cascade of hybridization to form a nicked double-helix polymer. Upon addition of the analytes (PDGF-BB or H1N1 DNA) and capture DNA immobilized on the SCGS, the nicked double-helix polymer binds on the surface of the SCGS through formation of a [capture DNA/analyte/signal DNA] sandwich structure. The GOx-biotin-streptavidin (SA) complexes were then attached to the nicked double-helix polymer through SA-biotin interaction. After cleavage by DNase I, the bound GOx is transferred into the buffer. Glucose is added and enzymatically oxidized to produce H2O2. The H2O2 formed oxidizes the substrate 3-(p-hydroxyphenyl)-propanoic acid to give a blue fluorescent product (with excitation/emission maxima at 320/416 nm) under the catalysis of horseradish peroxidase. Under optimal conditions, fluorescence increases linearly in the 0.5 to 70 pmol·L-1 PDGF-BB concentration range, and the detection limit is 191 fmol·L-1. For the H1N1 virus DNA, the respective data are 2.5 to 300 pmol·L-1 and 826 fmol·L-1. Graphical abstract Schematic presentation for detection of analytes (PDGF-BB or H1N1 virus DNA) based on the dual-signal amplification of Hybridization Chain Reaction (HCR) and glucose oxidase (GOx) using silver coated glass slide (SCGS) as separation material.
