Aptamer-mediated colorimetric and electrochemical detection of Pseudomonas aeruginosa utilizing peroxidase-mimic activity of gold NanoZyme

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.