Portable aptasensor for smartphones using trimetallic PtPdAuNFs and triplex molecular switch for rapid detection of procymidone

In this study, we developed a portable aptasensor utilizing a triplex molecular switch (THMS). This system is integrated with a portable electrochemical workstation and smartphone imaging technology, enabling rapid and on-site detection of procymidone (PCM). This system employs screen-printed electrodes based on trimetallic nanomaterials (PtPdAuNFs) and PolyA, integrating a portable electrochemical workstation with smartphone imaging technology, enabling rapid and on-site detection of procymidone (PCM). PtPdAuNFs were employed as signal tag materials, offering numerous active sites for the loading of signaling molecule methylene blue (MB) as well as the aptamer. These signal tags were combined with PolyA probe to form a stable THMS structure, which was then immobilized onto the surface of screen-printed electrodes. The unique continuous adenine sequence at the end of the PolyA probe facilitated the binding to the electrode surface, enhancing both the stability and performance of the sensor. Upon the addition of the target to the assembled aptasensor, the target selectively binds to the aptamer, triggering the opening of the THMS structure. This conformational change causes the signal tag to detach from the platform, resulting in a detectable signal alteration. The smart portable aptasensor developed in this study enables on-site detection of PCM with a detection limit of 50 pg·mL⁻¹ and a detection range spanning from 500 pg·mL⁻¹ to 500 ng·mL⁻¹. The sensor demonstrates excellent specificity and reproducibility, and has been successfully applied to real samples, including tomato and leek, with satisfactory recovery rates (93% ∼ 107%). These results highlight the promising potential of the developed sensor for detecting PCM and other contaminants in fruits and vegetables. Moreover, by modifying the DNA design, the prepared sensor was applied to the detection of other target analytes (Fipronil and Profenofos), achieving excellent detection performance. This sensor offers a valuable tool for food safety monitoring.