ABSTRACT
The aggravation of antibiotic resistance genes (ARGs) in the environment has posed a significant global health crisis. Accurate evaluation of ARGs levels in a facile manner is a pressing issue for environmental surveillance. Here, we demonstrate a unique dumbbell-shaped cascade nanozyme for visual/photoelectrochemical (PEC) dual-mode detection of ARGs. Gold nanoparticles (AuNPs) with tunable exposed facets are controllably anchored onto ZIF-8 dodecahedrons, exhibiting glucose oxidase (GOx)-like (ZIF-8@Au/G) and peroxidase (POD)-like (ZIF-8@Au/P) activities. Upon the occurrence of ARGs, an asymmetric cascade-amplified "dumbbell" configuration is spontaneously generated via target-induced DNA hybridization, comprising GOx-like ZIF-8@Au/G with capture DNA on one side and POD-like ZIF-8@Au/P with signal DNA on the opposite side. Such a cascade nano-system can efficiently oxidize colorless 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) into its green oxidation state and synergistically decompose H2O2, realizing colorimetric/PEC dual-mode ARGs detection with a detection limit of 0.112 nM. The applicability of the present bioassay is validated through measuring ARGs in real sludge samples. This work suggests the possibility to rationally design task-specific nanozymes and develop target-responsive nano-cascade assays for environmental monitoring.
Subject(s)
Biosensing Techniques , Colorimetry , Electrochemical Techniques , Gold , Metal Nanoparticles , Gold/chemistry , Biosensing Techniques/methods , Metal Nanoparticles/chemistry , Electrochemical Techniques/methods , Drug Resistance, Microbial/genetics , Hydrogen Peroxide/chemistry , Glucose Oxidase/chemistry , Limit of Detection , Peroxidase/chemistry , Metal-Organic Frameworks/chemistry , Zeolites/chemistryABSTRACT
As emerging contaminants in the environment, antibiotic resistance genes (ARGs) have aroused a global health crisis and posed a serious threat to ecological safety and human health. Thus, efficient and accurate onsite detection of ARGs is crucial for environmental surveillance. Here, we presented a colorimetric-photoelectrochemical (PEC) dual-mode bioassay for simultaneous detection of multiple ARGs by smartly incorporating rolling circle amplification (RCA) into a stimuli-responsive DNA nanoassembly, using the tetracycline resistance genes tetA and tetC as models. The tailored DNA nanoassembly containing RCA amplicons hybridized with specific signal probes: CuO nanoflowers-anchored signal DNA1 and HgO nanoparticles-anchored signal DNA2, respectively. Upon exposure to an acidic stimulus, numerous Cu2+ and Hg2+ were released, serving as the reporting agent of colorimetric/PEC dual-mode assay. The released Cu2+ and Hg2+ induced localized surface plasmon resonance shifts in Au nanorods and triangular Ag nanoplates through an etching process, respectively, enabling visual analysis of ARGs with distinguishing color changes. Meanwhile, numerous Cu2+ and Hg2+ triggered the amplified PEC variations via reacting with the photoactive layers of CuS/CdS and ZnS, respectively. Thus, a rapid and ultrasensitive colorimetric/PEC dual-mode detection of multiple ARGs was achieved with the detection limit down to 17.2 aM. Furthermore, such dual-mode bioassay could discriminate single-base mismatch and successfully determine ARGs in E. coli plasmids and sludge samples, holding great promise for point-of-care genetic diagnostics.
