An ultrasensitive electrochemical DNA sensor based on gold nanoparticle/ionic liquid–carbon nanotube nanocomposite for detecting vancomycin resistance genes in water

First electrochemical DNA sensor for detecting vancomycin resistance genes vanA / vanB . • Synergistic AuNPs/IL-CNT nanocomposite boosts signal amplification and probe loading. • Wide linear range (0.1 pM-10 nM) with an ultra-low detection limit of 0.1 pM. • Validation in real water samples shows 96.4–106.9% recovery and correlates with qPCR. • High specificity, good stability (RSD < 2.17%), detects variable-length fragments. The widespread occurrence of antibiotic resistance genes (ARGs) has become a severe global threat to environmental and public health. The detection of vancomycin resistance genes (VRGs) is particularly critical, given vancomycin's role as a last-line agent against multidrug-resistant Gram-positive bacteria. In this study, we developed a novel electrochemical DNA sensor for the ultrasensitive detection of VRGs, representing a novel electrochemical approach for VRG detection with significant performance advantages over existing methods for ARGs. The sensor incorporated a rationally designed layered interface. This interface was formed by immobilizing ionic liquid-functionalized carbon nanotubes (IL-CNT) onto a glassy carbon electrode to form a highly conductive substrate, which facilitated electron transfer and served as an ideal platform for the subsequent electrodeposition of gold nanoparticles (AuNPs). The resulting AuNPs/IL-CNT nanocomposite significantly increased the electroactive surface area and provided abundant sites for anchoring thiolated van A-specific single-stranded DNA probes. This synergistic multi-component architecture significantly enhanced both probe loading capacity and electrochemical signal transduction efficiency. The sensor demonstrated outstanding performance, including an exceptionally low detection limit of 0.1 pM, a short assay time of 40 min, high reproducibility (RSD < 1.18%), excellent selectivity, and good stability (RSD < 2.17%). Furthermore, results from detecting van A in various water samples were highly consistent with quantitative real-time polymerase chain reaction. Hence, this work presents a rapid, reliable, and highly sensitive platform for monitoring ARGs in real-world aquatic environments. Download: Download high-res image (128KB) Download: Download full-size image