Electrochemiluminescence drug detection with nanoparticle-encapsulated luminophore on screen-printed electrodes

The unprecedented demand for point-of-care testing devices has intensified research interests in developing miniature and cost-effective electroanalytical devices such as electrochemiluminescence (ECL) sensors. Here, we report a simple-structured and disposable ECL sensor platform for drug sensing applications. Our ECL sensor platform consists of screen-printed electrodes using an in-house formulated graphite-based ink, fabricated on flexible polyimide substrates. Silica (SiO2) nanoparticles with sizes of ∼100 nm are synthesized via an inverse microemulsion method, which encapsulates the ECL luminophore tris(2,2′-bipyridyl)ruthenium (II) chloride (Ru(bpy)3Cl2) in situ. The resulting Ru(bpy)32+@SiO2 nanocomposite helps to immobilize the ECL luminophore on the porous surface of screen-printed electrodes. The interface effect introduced by nanoparticles also enhances the ECL efficiency of the resultant sensor significantly by 33% (defined as thearbitrary unit per number of luminophores). The optimized flexible sensor is used for an ECL-based assay of a local anesthetic lidocaine and achieves a wide response range (0 −3.69 mM) and a respectable limit of detection (2.6 μM, S/N ≥ 3). We demonstrate a combination of nanotechnology with readily-available technology in designing scalable, low-cost, and miniature sensor platforms with excellent analytical performance. It serves as a firm foundation for developing point-of-care/in-field testing and wearable sensors for illicit drug detection, water and food security assessment, among other biosensing applications.