Ratiometric-enhanced G-Quadruplex Probes for Amplified and Mix-to-Read Detection of Mercury Pollution in Aquatic Products

Abstract

Mercury, as a global toxic pollutant, is easy to be accumulated in aquatic products and poses a great threat to human health. In this work, we proposed a mix-to-read, label-free, and robust assay for detecting mercury pollution in aquatic products by engineering a ratiometric-enhanced G-quadruplex probe. The transformation from the G-quadruplex to a hairpin-like structure allows us to confer a ratiometric and leveraged response to Hg 2+ , amplifying the signal-to-background ratio for Hg 2+ detection. Hg 2+ response was further improved by screening parallel-and antiparallel-, single-, and multiple-stranded G-quadruplex structures. Compared to the common aptamer probes, the ratiometric-enhanced G-quadruplex probe increased the sensitivity for Hg 2+ detection by 4.7 times. This proposed sensing system allowed a simple and one-tube homogenous detection of Hg 2+ at room temperature using a single unlabeled DNA sequence. Its application for Hg 2+ detection in fish and shrimp conferred satisfactory recovery rates ranging from 98.5 to 105.9%. The label-free and mix-to-read assay is promising for the onsite detection of mercury pollution and facilitating food safety of aquatic products.

G-Quadruplex-Probing CRISPR-Cas12 Assay for Label-Free Analysis of Foodborne Pathogens and Their Colonization In Vivo

“…We first optimized the assaying conditions of G-CRISPR-Cas including the G-quadruplex probes and gRNA, which correlated with signal output and cleavage efficiency. Typical G-quadruplex probes structured using single strand (TBA, PS2.M, and G3T6), two strands (ARGO 100) and four strands (T4G4) were tested. ,− The oligonucleotide sequences of different G-quadruplex probes are showed in Table S3 in the Supporting Information. As shown in Figure S2 in the Supporting Information, fluorescence intensity indicated that the G3T6 probe would yield a highest background-to-signal ratio.…”

“…The recognition and trans -cleavage activity of CRISPR-Cas12a could eliminate non-specific amplification signals derived from LAMP . A G-quadruplex and its specific dye ( N -methyl mesoporphyrin IX, NMM) are introduced to serve as the reporter of CRISPR-Cas12a, thus reducing the utilization of chemically labeled probes. The G-CRISPR-Cas assay can be carried in one test tube at a constant temperature, which is promising for on-site diagnosis of the infection or contamination of foodborne pathogens outside the laboratories.…”

Ag-β-Cyclodextrin-Graphene Oxide Ternary Nanostructures with Peroxidase-Mimicking Activity for Hg2+ Detection

“…In addition, it expresses a lower LOD or larger linear range for Hg 2+ detection than those reported previously by similar colorimetric analyses (Table S4). ,− …”

Advances in aptamer screening and aptasensors’ detection of heavy metal ions

“…The oxidase substrate 3,3′,5,5′-tetramethylbenzidine generates colored products under aerobic conditions, and the detection limit for Hg 2+ was 10.5 nM. Wu et al [ 98 ] designed an aptasensor based on G-quadruplex structure switching and T-Hg 2+ -T mismatch pair, and amplified the signal with two kinds of fluorescent dyes. Caglayan [ 99 ] applied SPR in another study to detect Hg 2+ and made a SPR aptasensor with a detection limit of 26 pM.…”