A 3D miniaturized solid-state chemiluminescence sensor based on ruthenium functionalized polymeric monolith for the detection of pharmaceutical drugs

Abstract: For the first time, a 3D network of poly(methacrylic acid-co-ethylene dimethacrylate (poly(MAA-co-EDMA)) monolith is used as a solid support for a miniaturized solid-state chemiluminescence (CL) system. The positively charged Ru(bpy)₃²⁺ complex was electrostatically linked to the negatively charged monolith to form Ru(bpy)₃²⁺-poly(MAA-co-EDMA). The Ru(bpy)₃²⁺-poly(MAA-co-EDMA) was thoroughly studied using Fourier-transform infrared spectroscopy (FTIR), surface area measurement, isoelectric point, scanning electron microscopy (SEM), UV–Vis, fluorescence and microwave plasma-atomic emission spectrometer (MP-AES). The results showed the successful formation of the 3D structure and the linkage of Ru(bpy)₃²⁺ onto its surface. Surface area measurements showed a drastic decrease in the surface area of the monolith from 80.9 to 5.58 m² g⁻¹ upon the introduction of Ru(bpy)₃²⁺ due to its incorporation within the micropores of the monolith. The 3D miniaturized solid-state CL platform was optimized by studying the effect of the concentration of the oxidant, the concentration of H₂SO₄ and the flow rate using oxalate as a model analyte. The optimized platform was then used for the detection of oxalate and two pharmaceutical drugs, namely methapyrilene and imipramine, for clinical and forensic applications. Under optimal conditions, the calibration curves of both methapyrilene and imipramine pharmaceutical drugs are linear over the range from 5 to 50 pM, with limits of detection of 6.8 and 8.2 pM, respectively. The limits of quantification of methapyrilene and imipramine were 20.6 and 24.7 pM, respectively. The developed Ru(bpy)₃²⁺-poly(MAA-co-EDMA) platform is disposable, cost-effective, highly sensitive and can be portable. Graphic abstract: [Figure not available: see fulltext.].