Label-Free and Enzyme-Free Colorimetric Detection of Pb²⁺ Based on RNA Cleavage and Annealing-Accelerated Hybridization Chain Reaction

Abstract

A label-free and enzyme-free colorimetric sensor for rapid detection of Pb2+ is reported, which is based on the strategy of DNAzyme-mediated RNA cleavage combined with an annealing-accelerated DNA hybridization chain reaction (HCR). As a trigger DNA, the substrate strand (STM) of DNAzyme can initiate HCR effectively. However, when it is cleaved by DNAzyme in the presence of Pb2+, the separation of DNA functional domains leads to a serious decrease in HCR efficiency. As a result, the difference in Pb2+ concentration converts into the difference of DNA assembly, which eventually leads to the color change of colloidal gold nanoparticles (AuNPs). In this work, a DNA strand (cGR5) completely complementary to the catalytic strand (GR5) of DNAzyme is used to improve the dissociation of STM to enhance the HCR efficiency. In addition, the simple operation of DNA annealing is first used to accelerate the HCR process, enabling the Pb2+ detection to be completed in about 30 min. As advantages of high sensitivity, good selectivity, strong anti-interference ability, and good practical performance are achieved, it is anticipated that the cheap and simple colorimetric sensor will be helpful for on-site detection of environmental and food samples.

An Autonomous Nonenzymatic Concatenated DNA Circuit for Amplified Imaging of Intracellular ATP

“…Meanwhile, some enzyme-free amplification strategies are explored with satisfactory performance for intracellular assay, including catalytic nucleic acid, − catalyzed hairpin assembly, − and hybridization chain reaction (HCR) circuits. − HCR involves the analyte-motivated self-assembly of hairpin reactants to generate long dsDNA nanowires . The successive and continuous cross-hybridization features of HCR amplifier enabled its extensive application in detecting various nucleic acids − and small molecules. − However, these enzyme-free ATP aptasensors are always confronted with comparably lower amplification capacity. Thus, it is essentially important to design more aptasensing strategies with higher signal gain for in situ monitoring the varied ATP expressions in living cells.…”

Gold nanoparticle-based optical nanosensors for food and health safety monitoring: recent advances and future perspectives

“… 147 Besides, the interaction between DNAzyme and Pb 2+ also attract researchers' concern for anti-aggregation approach. 148 In the presence of Pb 2+ , DNAzyme would cleavage the target sequence. Therefore, this phenomenon was employed to separate AuNPs and graphene quantum dots in a 2018 study, resulting in fluorescence recovery ( Fig.…”

Design Strategies of Gold Nanoparticles‐Based Biosensors Coupled with Hybridization Chain Reaction or Catalytic Hairpin Assembly

“…In contrast, without Pb 2 + , HCR was triggered by the initiator strand and the AuNPs aggregated after adding salt. [26] Another approach is by using AuNPs functionalised with capture probes to hybridize with target. The immobilized target forms elongated HCR concatemers upon reacting with individual hairpins and results in dendrimer-like HCR products surrounding the AuNPs (Scheme 2B).…”