Smart pH-Regulated Switchable Nanoprobes for Photoelectrochemical Multiplex Detection of Antibiotic Resistance Genes.

Antibiotic resistance, encoded via particular genes, has become a major global health threat and substantial burden on healthcare. Hence, the facile, low-cost, and precise detection of antibiotic resistance genes (ARGs) is crucial in the realm of human health and safety, especially multiplex sensing assays. Here, a smart pH-regulated switchable photoelectrochemical (PEC) bioassay has been created for ultrasensitive detection of two typical subtypes of penicillin resistance genes (target 1, labeled as T) and (target 2, labeled as T), whereby pH-responsive antimony tartrate (SbT) complex-grafted silica nanospheres are ingeniously adopted as signal DNA1 tags (labeled as S-SbT@SiONSs). The operations of the PEC bioassay depend on the switchable dissociation of the pH-responsive S-SbT@SiONSs complex under the external pH stimuli, thus initiating the pH-regulated release of ions pre-embedded in sandwich-type DNA nanoassemblies. At acidic conditions, the dissociation of S tags (ON state) triggers the release of the embedded SbO. Under alkaline conditions, the dissociation of S tags is inhibited (OFF state). The detection of T was achieved via DNA hybridization-triggered metal ion release. The unwinding of the introduced hairpin T-Hg-T fragment, hybridized with the second anchored signal DNA (S), ignites the release of Hg. The released SbO or Hg ions would trigger the formation of SbS/ZnS or HgS/ZnS heterostructure through ion-exchange with the photosensitive ZnS layer, giving rise to the amplified photocurrents and eventually realizing the ultrasensitive detection of penicillin resistance genes subtypes, and a. The as-fabricated pH-regulated PEC bioassay, smartly integrating the pH-responsive intelligent unit as S tags, pH-regulated release of embedded ions, and the subsequent ion-exchange-based signal amplification strategy, exhibits high sensitivity, specificity, low-cost, and ease of use for multiplex detection of ARGs. It can be successfully used for measuring and in real plasmids, demonstrating great promise for developing a new class of genetic point-of-care devices.