Amplification-free electrochemiluminescence biosensors based on peptide-templated gold nanocluster and CRISPR-Cas12a for Mycobacterium tuberculosis IS6110 detection.

BACKGROUND

Tuberculosis (TB) nucleic acid diagnosis urgently requires rapid, amplification-free methods to overcome limitations of quantitative real-time polymerase chain reaction (qPCR), including instrument dependency, prolonged time, and contamination risks from nucleic acid amplification.

RESULTS

Here, an amplification-free electrochemiluminescence (ECL) biosensor based on peptide-templated gold nanoclusters and the clustered regularly interspaced short palindromic repeats-Cas12a system (CRISPR-Cas12a) has been constructed for the detection of Mycobacterium tuberculosis (MTB)-specific IS6110 sequences. Peptide-templated gold nanoclusters with low background and high ECL response can be used as sensitive signal probes. When CRISPR-Cas12a recognizes the target IS6110 DNA, it exhibits non-specific cleavage activity, repeatedly cleaving ferrocene-labelled DNA. This results in the restoration of ECL signals quenched by ferrocene, thereby achieving signal amplification. There is a linear relationship between the signal and the target concentration range from 10 CFU/mL to 104 CFU/mL, with a detection limit of 7 CFU/mL (S/N = 3). Clinical validation (n = 40) showed strong agreement with qPCR (κ = 0.90).

SIGNIFICANCE: Critically, this amplification-free strategy eliminates the need for temperature cycling equipment, reduces detection time to 1 h, and completely avoids the risk of amplicon contamination, providing an ideal solution for rapid screening of highly infectious diseases such as TB.