Fluorescent sensing platform based on two-dimensional layered double hydroxides and exonuclease I for DNA and microRNA detection

Interfacial and interlayer interactions between layered double hydroxides (LDHs) and nucleic acids offer LDHs great potential to absorb and detect nucleic acids. Herein, we demonstrate a simple, rapid, and versatile fluorescent sensing platform based on two-dimensional LDHs and exonuclease I (Exo I) for the selective analysis of DNA and microRNA. ZnNiAl-LDHs were utilized as quenchers for FAM labelled on single-stranded DNA (ssDNA) probes via dynamic quenching with high fluorescence quenching ability. The quenching mechanism was explored by means of spectral analysis, characterization experiments, DNA adsorption and desorption studies, zeta potential analysis, and molecular dynamics simulations. The driving forces for the adsorption of LDHs toward fluorophore-labelled nucleic acids were confirmed to be electrostatic interaction, van der Waals force, and anion exchange for the first time. In order to distinguish the formed target/probe duplexes from FAM-ssDNA probes, Exo I was introduced to specifically hydrolyze FAM-ssDNA probes. The fabricated fluorescent sensing platform for nucleic acids detection shows a low detection limit of 0.08 nM. Finally, this sensor was effectively utilized for the detection of DNA and microRNA in actual biological and environmental samples, achieving recoveries ranging from 96.4 % to 105 %, indicating high accuracy. This work proposed a promising sensing platform for sequence-specific nucleic acids detection, and provides a new perspective on two-dimensional LDHs as structural supports and biomolecular reservoirs for biomedical applications.