Issue 41, 2023

Tetrahedral DNA nanostructure-corbelled click chemistry-based large-scale assembly of nanozymes for ratiometric fluorescence assay of DNA methyltransferase activity

Abstract

Ligation efficiency in a surface-based DNA click chemistry (CuAAC) reaction is extremely restricted by the orientation and density of probes arranged on a heterogeneous surface. Herein, we engineer DNA tetrahedral nanostructure (DTN)-corbelled click chemistry to trigger a hybridization chain reaction (HCR) assembling a large-scale of nanozymes for ratiometric fluorescence detection of DNA adenine methyltransferase (Dam). In this study, a DNA tetrahedron structure with an alkynyl modifying pendant DNA probe (Alk-DTN) is designed and assembled on a magnetic bead (MB) as a scaffold for click chemistry. When a CuO NP-encoded magnetic nanoparticle (CuO-MNP) substrate was methylated by Dam, CuO NPs were released and turned into a mass of Cu+. The Cu+ droves azido modifying lDNA (azide-lDNA) to connect with the Alk-DTN probe on the MB through the click reaction, forming an intact primer to initiate the HCR. The HCR product, a rigid structure double-stranded DNA, periodically assembles glucose oxidase mimicking gold nanoparticles (GNPs) into a large-scale of nanozymes for catalyzing the oxidation of glucose to H2O2. NH2-MIL-101 MOFs, a fluorescent indicator and a biomimetic catalyst, activated the product H2O2 to oxidize o-phenylenediamine (oPD) into visually detectable 2,3-diaminophenazine (DAP). The change of the signal ratio between DAP and NH2-MIL-101 is proportional to the methylation event corresponding to the MTase activity. In this study, the DTN enhances the efficiency of the surface-based DNA click reaction and maintains the catalytic activities of gold nanoparticle nanozymes due to the intrinsic nature of mechanical rigidity and well-controlled orientation and well-adjusted size. Large-scale assembly of nanozymes circumvents the loss of natural enzyme activity caused by chemical modification and greatly improves the amplification efficiency. The proposed biosensor displayed a low detection limit of 0.001 U mL−1 for Dam MTase due to multiple amplification and was effective in real samples and methylation inhibitor screening, providing a promising modular platform for bioanalysis.

Graphical abstract: Tetrahedral DNA nanostructure-corbelled click chemistry-based large-scale assembly of nanozymes for ratiometric fluorescence assay of DNA methyltransferase activity

Supplementary files

Article information

Article type
Paper
Submitted
09 Aug. 2023
Accepted
28 Sept. 2023
First published
03 Okt. 2023

J. Mater. Chem. B, 2023,11, 9912-9921

Tetrahedral DNA nanostructure-corbelled click chemistry-based large-scale assembly of nanozymes for ratiometric fluorescence assay of DNA methyltransferase activity

G. Cao, H. Jia, S. Xu, E. Xu, P. Wang, Q. Xue and H. Wang, J. Mater. Chem. B, 2023, 11, 9912 DOI: 10.1039/D3TB01795H

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