A novel disposable electrochemical biosensor based on DNA-gated metal–organic frameworks and isothermal amplification for sensitive pathogen gene detection

Abstract

To address the urgent need for rapid and ultrasensitive detection of foodborne pathogens, this study introduces a novel electrochemical biosensing platform that integrates DNA-gated metal-organic frameworks (MOFs) with rolling circle amplification (RCA) for enhanced signal output. This is the first reported biosensor to employ MOFs as nanocarriers for signal molecules in conjunction with RCA, offering a powerful and innovative strategy for nucleic acid-based molecular diagnostics. A pathogenic gene from Staphylococcus aureus (S. aureus), a major foodborne pathogen capable of producing enterotoxins, was selected as the model target. In the proposed sensing mechanism, MOFs are pre-loaded with methylene blue (MB), which is confined within the porous structure via hybridized blocker DNA. Upon recognition of the target gene, RCA is initiated to produce long, repetitive DNA strands that displace the blocker DNA, effectively unsealing the MOFs and releasing MB to generate a strong electrochemical signal. The synergy between the high signal amplification efficiency of RCA and the superior cargo-loading capacity of MOFs results in a highly sensitive detection performance, achieving an ultralow detection limit of 1.89 fM and a broad dynamic range from 1 pM to 10 nM—surpassing the sensitivity of most existing biosensors. Furthermore, this platform offers modularity and flexibility; by simply altering the probe sequence, it can be adapted to detect a variety of targets. This study not only demonstrates a novel method for detecting the pathogenic gene of S. aureus, but also establishes a broadly applicable biosensing platform with great potential for food safety monitoring and clinical diagnostics.