Despite of various advancements in biosensing, a rapid, accurate, and on-site detection of a bacterial pathogen is a real challenge due to the lack of appropriate diagnostic platforms. To address this unmet need, we herein report an aptamer-mediated tunable NanoZyme sensor for the detection of Pseudomonas aeruginosa, an infectious bacterial pathogen. Our approach exploits the inherent peroxidase-like NanoZyme activity of gold nanoparticles (GNPs) in combination with high affinity and specificity of a Pseudomonas aeruginosa–specific aptamer (F23). The presence of aptamer inhibits the inherent peroxidase-like activity of GNPs by simple adsorption on to the surface of GNPs. However, in the presence of cognate target (P. aeruginosa), owing to the high affinity for P. aeruginosa, the aptamer leaves the GNP surface, allowing GNPs to resume their peroxidase-like activity, resulting in oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). As TMB is an electrochemically active species, we have been able to translate the NanoZyme-based method into an ultrasensitive electrochemical assay using disposable carbon screen-printed electrode. This approach is highly sensitive and allows us to rapidly detect P. aeruginosa with a low-end detection limit of ~ 60 CFU/mL in water within 10 min. This generic aptamer-NanoZyme-based electrochemical sensing strategy may, in principle, be applicable for the detection of various other bacterial pathogens.
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The authors acknowledge the generous support provided by Prof. Jaya S. Tyagi and Dr. H.K. Prasad in providing laboratory access to handle the bacterial cultures.
T.K.S. is thankful to THSTI Core grant and the Department of Biotechnology Govt. of India for Innovation Award and Innovative Young Biotechnologist Award (BT/010/IYBA/2016/10). V.B. thanks the Australian Research Council (ARC) for a Future Fellowship (FT140101285) and research support through an ARC Discovery (DP170103477) grant. V.B. also recognizes the generous support of the Ian Potter Foundation toward establishing the Sir Ian Potter NanoBioSensing Facility at RMIT University. A.D. is thankful to the Indian Council for Medical Research for providing Senior Research Fellowship.
Compliance with ethical standards
This research does not involve any human participant or animals.
Conflict of interest
The authors declare that they have no conflict of interest.
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