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Turkish Journal of Chemistry

Abstract

Colorimetric biosensing devices represent an important class of point-of-care (POC) diagnostics due to their ability to provide visible test outputs, their ease of integration with smartphone-based sensing, and their portability for field testing. In the context of agrifood safety, there is a growing need for portable, robust, and cost-effective detection devices. Pesticide residues can be present in a wide range of environmental and food samples, from water resources to fruits and vegetables, resulting in an increasing global demand for on-site testing. Colorimetric assays, when combined with smartphone-based sensing, can effectively address these needs. In this work, the aggregation-induced color change response of aptamer–gold nanoparticle conjugates was exploited to design a lab-in-a-tube colorimetric assay for the detection of malathion. The performance of the assay was evaluated using both a conventional spectrophotometric method as a laboratory-based reference and a smartphone-based readout supported by color intensity analysis as a portable detection approach. Color responses were quantified using both a mobile application and computer software across different color channels. The smartphone-based readout yielded a limit of detection (LOD) of 5.14 mg/mL and a linear detection range of 0.02–100 mg/mL with a correlation coefficient (R2) of 0.9981 for the mobile application, while the computer software-based analysis exhibited an LOD of 0.88 mg/mL, a linear range of 0.02–50 mg/mL, and an R2 of 0.9789. In comparison, the spectrophotometric method showed an LOD of 1.67 mg/mL, a linear range of 0.02–100 mg/mL, and an R2 of 0.9948, confirming the reliability of the smartphone-based approaches. The results demonstrate that the colorimetric assay developed can be successfully integrated with smartphones for field-testing applications, while providing a competitive LOD comparable to laboratory-based methods.​

Author ORCID Identifier

EMİNE GÜLER ÇELİK: 0000-0003-2381-9775

DOI

10.55730/1300-0527.3902

Keywords

Colorimetric assays, point-of-care diagnostics, gold nanoparticle, aptamer, pesticide detection, smartphone sensing

First Page

359

Last Page

368

Publisher

The Scientific and Technological Research Council of Türkiye (TÜBİTAK)

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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