Quasi-Photonic Crystal Light-Scattering Signal Amplification of SiO2‑Nanomembrane for Ultrasensitive Electrochemiluminescence Detection of Cardiac Troponin I

Signal amplification for electrochemiluminescence (ECL) plays a significant role in ultrasensitive detection of disease biomarkers. We report herein a new signal amplification strategy–quasi-photonic crystal nanomembrane-based light scattering enhancement for ECL signal amplification, via fabricating a novel close-packed monolayered SiO2-nanomembrane as solid-state ECL electrodes. In the system, the quasi-photonic crystal structure of the monolayered SiO2-nanomembrane led to intense light scattering within the nanofilm, which significantly increases the photon flux and then definitely improves the excitation number of the luminescent molecules (Ru­(bpy)3 2+). Reinforced by the nanostructured electrode surface of the nanomembrane, the as-prepared ECL electrode exhibited significant ECL enhancement, ∼77-fold enhancement in the classic Ru­(bpy)3 2+-TPrA system. We further constructed a sandwich-type SiO2-nanomembrane based solid-state ECL immunobiosensor for ultrasensitive detection of cardiac troponin I (cTnI). Under optimal conditions, the immunobiosensor exhibited a very low limit of detection (LOD) of 5.6 fg mL–1 for cTnI. Due to the cheap and easy availability of the materials, this study and findings not only provide an efficient way to improve the ECL intensity but also benefit the design of novel ECL electrodes for various biomarker detections.