Smartphone-integrated colorimetric and microfluidic paper-based analytical devices for the trace-level detection of permethrin

[Display omitted] •Novel colorimetric sensing of permethrin is reported for the first time.•Metronidazole-functionalized silver nanoparticles are used as a sensing probe.•Smartphone color detection apps and microfluidic paper-based devices are combined.•The proposed system is applied for the onsite detection of permethrin.•Permethrin detection is compared with the USEPA-recommended UPLC method. Permethrin is a pyrethroid pesticide and insect repellent that prevents mosquito-borne infections like dengue and malaria in tropical areas. This work describes a new colorimetric sensor based on metronidazole-stabilized silver nanoparticles (MTZ-AgNPs) for the first rapid, sensitive, and selective permethrin detection. The MTZ-AgNPs-based colorimetric sensor has a limit of detection (LOD) of 0.0104 µM and a limit of quantification (LOQ) of 0.0348 µM, respectively. The sensor is further integrated with smartphone and microfluidic fabrication of paper-based analytical devices (µPADs) for real-time and on-site detection of permethrin. Under optimal settings, no potential environmental contaminants interfere with permethrin detection, confirming its high selectivity. Finally, the practical applicability of sensors is confirmed in real tomato and apple extract samples. The US environmental protection agency's recommended UPLC method validated the detection efficiency of the proposed colorimetric sensor. The % recoveries from UPLC and MTZ-AgNPs suggest that the present sensor can quantitatively analyze permethrin in real samples.