Ultrasensitive and On-Site Detection of Carbaryl Pesticides via Dual-Mode Nanosensors Utilizing Portable Devices

High-efficiency detection technologies of carbaryl residues are significant due to their adverse effects on the environment and human health. To achieve accurate in situ analysis, we designed a portable device integrated with a smartphone sensing platform for rapid, visual quantitative determination of carbaryl via colorimetric and fluorescent signals. Amino-modified gold nanoparticles (AuNPs), blue-emitting silicon quantum dots (Si QDs), and red-emitting cadmium telluride quantum dots (CdTe QDs) were used as opto-sensing centers. The carbaryl triggered the agglomeration of the as-synthesized AuNPs by an electrostatic effect, resulting in a specific change in UV–vis absorption. The blue fluorescence of Si QDs recovered, while the red fluorescence of CdTe QDs quenched, enabling fluorescence color variation from red to blue for visual monitoring. The ratiometric fluorescent signals are available for quantitative analysis in the range of 6 to 200 μM, with a limit of 16.3 nM for fluorescence detection and 49.6 nM for colorimetric sensitivity detection. Coupling widely used three-dimensional print and application software, we constructed the smartphone platform to output the ratio of red and blue channel values of captured fluorescence images to meet the needs of on-site analysis in real samples. This work imposed great improvement in ratiometric sensing for carbamate pesticide residues and broadened the portable quantitative sensing device in chemical sensing applications.