Tomography Electrogenerated Chemiluminescence Imaging from Magnetic Microbeads

Electrogenerated chemiluminescence (ECL) bioassay has witnessed remarkable growth in biosensing and diagnostics. An understanding of the reaction mechanism within ECL is important for improving and designing sensitive ECL methods. Herein, a sidelong ECL microscopy and finite element simulation are developed for tomography imaging from single magnetic microbeads and deciphering reaction mechanism within bead-based coreactant ECL system. Ruthenium derivative labeled magnetic beads (Ru1-Mag@MB) and tri-n-propylamine are chosen as typical coreactant ECL systems. ECL emissions from Ru1-Mag@MB in different conditions are imaged via the sidelong ECL microscopy, which can allow the spatially resolved measurement of the ECL emitting layer from single microbeads in the vertical direction of the electrode surface. Surface-confined ECL emissions are mainly observed at or near the interface between the electrode surface and the Ru1-Mag@MB. The surface distribution plots of ECL intensity, and tomography ECL, across single Ru1-Mag@MB display "first increase and then decrease" phenomena. The ECL intensity and emission extension are varied with the change of the radical lifetime, the kinetics of chemical reactions, and the optical parameters of microbeads. The sidelong ECL microscopy with the tomography of the ECL emitting layer can provide a promising way for insightful mechanistic information within a bead-based ECL system.