Covalent organic frameworks as micro-reactors: confinement-enhanced electrochemiluminescence

• Published in: Chemical science (Cambridge) Vol. 11; no. 21; pp. 541 - 5414
• Main Authors: Zeng, Wei-Jia, Wang, Kun, Liang, Wen-Bin, Chai, Ya-Qin, Yuan, Ruo, Zhuo, Ying
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.06.2020; The Royal Society of Chemistry
• Subjects: Aflatoxin M1; Aqueous solutions; Chemistry; Confinement; Electrochemical oxidation; Electrochemiluminescence; Hydrophobicity; Lipophilicity; Microreactors; Nanochannels; Reactors; Ruthenium; Ruthenium compounds; Stability
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d0sc01817a

Electrochemiluminescence (ECL) micro-reactors with enhanced intensity and extreme stability were first established by the assembly of tris(2,2′-bipyridyl) ruthenium( ii ) (Ru(bpy) 3 2+ ) onto covalent organic frameworks (COFs), in which a type of imine-linked COF (denoted as COF-LZU1) was employed as a model for ECL micro-reactors. Compared with the dominant ECL system of Ru(bpy) 3 2+ /tri- n -propylamine (TPrA) (TPrA as a co-reactant), the intensity of the COF-LZU1 micro-reactor-based electrode was significantly increased nearly 5-fold under the same experimental conditions, which is unprecedented in other Ru(bpy) 3 2+ -based ECL systems. This enhancement can be attributed to the large surface area, delimited space, and stable and hydrophobic porous structure of COF-LZU1, which not only enabled a huge amount of Ru(bpy) 3 2+ to be loaded in/on COF-LZU1, but also enriched a large amount of TPrA from the aqueous solution into its inner hydrophobic cavity due to the lipophilicity of TPrA. More importantly, with its hydrophobic porous nanochannels, COF-LZU1 could act as micro-reactors to provide a delimited reaction micro-environment for the electrochemical oxidation of TPrA and the survival of TPrA&z.rad;, achieving significant confinement-enhanced ECL. To prove this principle, these Ru@COF-LZU1 micro-reactors were developed to prepare an ECL aptasensor for aflatoxin M1 (AFM1) detection with a wide detection range and a low detection limit. Overall, this work is the first report in which ECL micro-reactors are constructed with COFs to enhance the intensity and stability of the Ru(bpy) 3 2+ -based ECL system, and opens a new route to the design of other ECL micro-reactors for bioanalysis applications. The electrochemiluminescence (ECL) micro-reactors with enhanced intensity and extreme stability were firstly established, unravelling the mechanism of ECL micro-reactors using COF-LZU1 assembled Ru(bpy) 3 2+ as a case study.