Nanoparticle-enhanced in-line potentiometric ion sensor for point-of-care diagnostics for tropicamide abuse in biological fluid.

Fares, M. Y., N. S. Abdelwahab, M. A. Hegazy, M. M. Abdelrahman, A. M. Mahmoud, and G. M. El-Sayed, "Nanoparticle-enhanced in-line potentiometric ion sensor for point-of-care diagnostics for tropicamide abuse in biological fluid.", Analytica chimica acta, vol. 1192, pp. 339350, 2022.


Point of care (POC), also identified as on-site testing, has evolved as a rapid and accurate technique for drug of abuse screening and analysis. The aim of this work is to detect tropicamide (TPC) abuse in biological fluids; we selected rat plasma as example. We developed a disposal miniaturized, portable, green, and budget-friendly POC solid-state electrochemical sensor based on potentiometric transduction. To attain that, an innovative microfabricated electrode modified with conducting polymer poly(3-octylthiophene) (POT) has been placed on sensitized printed circuit board (PCB). A two-stage optimization process was implemented to develop the fabricated electrode. The first stage of the optimization process depends on screening various ionophores in order to enhance the sensor selectivity towards tropicamide. Copper nanoparticles exhibited the highest selectivity towards TPC. The second stage was utilizing a polymer as an ion-to-electron transducer layer between the copper nanoparticles impregnated ion sensing membrane and the microfabricated solid-contact ion-selective electrode. This polymer was added to boost the stability of the potential drift (1.2 mV/h) due to the hydrophobic behavior of the POT, which precludes the formation of an aqueous layer at the Cu electrode/polymeric membrane interface and improve the limit of detection (1.1 × 10 M). Nernstian potentiometric response was accomplished for TPC with a slope of 58.46 ± 0.43 mV/decade and E ∼ 189.39 ± 2.12 over the concentration range 1.0 × 10 to 1.0 × 10 M. The suggested sensor's intrinsic figure of merits include a quick response time (13 ± 2 s) and long life time (45 days). The proposed sensor has been successfully employed in the selective determination of TPC in pharmaceutical formulations, and biological fluids. When the results were compared to those of the official approach, there was no statistically significant difference. The Eco-Scale tool assessed and measured the greenness profile of the established method.