Opto-sensing of sotalol using parafilm and poly(methyl methacrylate) micro-plates decorated by silver nanoparticles: state-of-the-art for one-drop pharmaceutical analysis†

Sotalol is an antiarrhythmic drug with a narrow therapeutic index and potential adverse effects, including hypotension and heart block, requiring continuous and precise blood-level monitoring. In this study, an innovative optical sensor was developed using silver nanoparticle (AgNP)-functionalized parafilm (PF)- and poly methyl methacrylate (PMMA) for the trace-level detection of sotalol in human blood plasma. The detection was performed using CMYK-based colorimetric digital image analysis via the Color Picker software app, achieving a low limit of quantification of 1 μM and a linear range of 0.001 to 20 mM. The selectivity of the sensor was also validated in the presence of potentially interfering cardiovascular drugs. Nanoparticle characterization revealed a shift in zeta potential (Z_p) from −14.5 to −6.16 mV, confirming a strong interaction between sotalol and AgNPs, as the optical probe. The sensor offers an innovative, cost-effective, portable, and rapid (5-min analysis time) approach for detecting sotalol in blood plasma. This sensor holds significant potential for point-of-care diagnostics and on-site drug monitoring, providing a reliable alternative to conventional, lab-dependent analytical methods for therapeutic drug monitoring.