Sensitive Fluorescent Sensor for Recognition of HIV-1 dsDNA by Using Glucose Oxidase and Triplex DNA

A sensitive fluorometric sensor for Ag+ based on the hybridization chain reaction coupled with a glucose oxidase dual-signal amplification strategy

In this work, an efficient and sensitive fluorometric sensor was developed to detect silver ions (Ag⁺). It is based on the cytosine–Ag⁺–cytosine (C–Ag⁺–C) structure via a dual-signal amplification strategy using glucose oxidase (GOx) and the hybridization chain reaction (HCR). A silver-coated glass slide (SCGS) acts as an ideal material for separation. Cytosine rich (C-rich) capture DNA (C-DNA) assembled themselves on the SCGS via Ag–S bonds and hybridized with signal DNA (S-DNA) to trigger the HCR. With specific base-pairing, the S-DNA and HCR products bind on the SCGS. Then, the GOx–biotin–streptavidin (SA) complexes bind to the HCR products through SA–biotin interactions. Owing to the formation of a particular C–Ag⁺–C structure between two neighboring C-rich C-DNA on the SCGS, the C-DNA/S-DNA/HP1-GOx/HP2-GOx complex gradually moved away from the SCGS as the concentration of Ag⁺ increased and the combined GOx fell into the buffer. H₂O₂ could be generated during the oxidation of glucose, catalyzed by GOx in the buffer. Afterward, H₂O₂ could oxidize the substrate (3-(p-hydroxyphenyl)-propanoic acid) when Horseradish peroxidase was present, giving rise to blue fluorescence. The proposed strategy reached a limit of detection (LOD) of 1.8 pmol L⁻¹ with a linear detection range of 5 to 1000 pmol L⁻¹ for Ag⁺. Moreover, this assay has been commendably used for the detection of Ag⁺ in actual samples with fairly good results.

An assay for Ag⁺ based on a C–Ag⁺–C structure by utilizing a HCR/GOx dual-signal amplification strategy and SCGS as an ideal separation material.

Sensitive fluorometric determination of platelet-derived growth factor BB and avian influenza A virus DNA via dual signal amplification using the hybridization chain reaction and glucose oxidase assisted recycling

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.