Electrochemical plasmonic optical fiber probe for real-time insight into coreactant electrochemiluminescence

Electrochemical surface plasmon resonance (ESPR) is a powerful technique for defining dynamic changes in chemical composition and morphology of functional interfaces by correlating spectral information with voltammetric characteristics of the electrode processes. However, conventional Kretschmann prism-based surface plasmon resonance (SPR) configurations require sophisticated apparatus and complex optics. Here, we present a versatile flow injection ESPR device that incorporates a plasmonic and conductive fiber optic probe, for which a gold nanohole array film is integrated onto the endface of a conventional optical fiber via template transfer. The coreactant-based Ru(bpy)(3)(2+) / tripropylamine (TPrA) electrochemiluminescence (ECL) system, was chosen to + unravel electrochemically-induced real-time interfacial information, since such an approach is increasingly employed for clinical assay analysis and the associated ECL mechanism is an active area of investigation. The ESPR observations provide novel experimental evidence to support the proposition that the ECL reactions undergo an oxidative-reduction pathway. Moreover, the ESPR peak shift exhibits a broader linear detection range of TPrA concentration (0.02-20 mmol L-1, R-2 = 0.996), compared to the ECL and SPR techniques (< 10 mmol L-1). This study clearly demonstrates that the novel fiber optic ESPR device presents as a reliable and multimodal spectroelectrochemical platform to gain mechanistic insights into complicated chemical processes and provide sensing capabilities, while offering great simplicity, portability and miniaturization.