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Aptasensor based on fluorophore-quencher nano-pair and smartphone spectrum reader for on-site quantification of multi-pesticides.

ABSTRACT: Current techniques for the detection of multi-pesticides are limited by technical complexity, sensitivity and cost. There is an urgent demand of developing new specific recognition elements and sensitive signal readouts for on-site monitoring. In this work, we developed a fluorescent aptamer-based lateral flow biosensor (apta-LFB) integrated with fluorophore-quencher nano-pairs and a smartphone spectrum reader to accomplish triple-target detection of chlorpyrifos, diazinon, and malathion. Aptamers serve as alternative recognition elements instead of antibodies in LFB, offering better specificity and stability. A novel fluorophore-quencher nano-pair (quantum dots nanobeads and gold nanostars) was implemented to perform "signal-on" instead of "signal-off". After optimization, detection limit of chlorpyrifos, diazinon, and malathion were determined to be 0.73 ng/mL, 6.7 ng/mL, and 0.74 ng/mL, respectively. Greatly increased sensitivity may come from the combination of improved signal and zero background. This innovative cascade strategy allowed to lower the detection limit of pesticides residue level in food, which is largely considered satisfactory. The accuracy and practicality of this design for effective on-site quantification of multi-pesticides were further confirmed using 12 vegetable and fruit samples. The estimated recoveries were between 82.4% and 112.8% in spiked vegetable samples, which indicated that the developed method is capable for detecting multi-pesticides in food samples. This sensitive handheld-system is promising to become a powerful tool for practical on-site application of multi-pesticide quantification procedures.

SUBMITTER: Cheng N

PROVIDER: S-EPMC8672368 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Water quality is undergoing significant deterioration due to bacteria, pollutants and other harmful particles, damaging aquatic life and lowering the quality of drinking water. It is, therefore, important to be able to rapidly and accurately measure water quality in a cost-effective manner using e.g., a turbidimeter. Turbidimeters typically use different illumination angles to measure the scattering and transmittance of light through a sample and translate these readings into a measurement based on the standard nephelometric turbidity unit (NTU). Traditional turbidimeters have high sensitivity and specificity, but they are not field-portable and require electricity to operate in field settings. Here we present a field-portable and cost effective turbidimeter that is based on a smartphone. This mobile turbidimeter contains an opto-mechanical attachment coupled to the rear camera of the smartphone, which contains two white light-emitting-diodes to illuminate the water sample, optical fibers to transmit the light collected from the sample to the camera, an external lens for image formation, and diffusers for uniform illumination of the sample. Including the smartphone, this cost-effective device weighs only ~350 g. In our mobile turbidimeter design, we combined two illumination approaches: transmittance, in which the optical fibers were placed directly below the sample cuvette at 180° with respect to the light source, and nephelometry in which the optical fibers were placed on the sides of the sample cuvette at a 90° angle with respect to the to the light source. Images of the end facets of these fiber optic cables were captured using the smart phone and processed using a custom written image processing algorithm to automatically quantify the turbidity of each sample. Using transmittance and nephelometric readings, our mobile turbidimeter achieved accurate measurements over a large dynamic range, from 0.3 NTU to 2000 NTU. The accurate performance of our smartphone-based turbidimeter was also confirmed with various water samples collected in Los Angeles (USA), bacteria spiked water samples, as well as diesel fuel contaminated water samples. Having a detection limit of ~0.3 NTU, this cost-effective smartphone-based turbidimeter can be a useful analytical tool for screening of water quality in resource limited settings.

Dataset Information

Aptasensor based on fluorophore-quencher nano-pair and smartphone spectrum reader for on-site quantification of multi-pesticides.

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