Pyrene-Based Metal–Organic Frameworks with Coordination-Enhanced Electrochemiluminescence for Fabricating a Biosensing Platform
Yang Yang, Jun-Mao Wang, Wenbin Liang, Yan Li, Ruo Yuan, Dong‐Rong Xiao
Abstract
Enhancing the electrochemiluminescence (ECL) properties of polycyclic aromatic hydrocarbons (PAHs) is a significant topic in the ECL field. Herein, we elaborately chose PAH derivative luminophore 1,3,6,8-tetrakis( p -benzoic acid)pyrene (H 4 TBAPy) as the organic ligand to synthesize a new Ru-complex-free ECL-active metal–organic framework Dy-TBAPy. Interestingly, Dy-TBAPy exhibited a more brilliant ECL emission and higher ECL efficiency than H 4 TBAPy aggregates. On the one hand, TBAPy luminophores were assembled into rigid MOF skeleton via coordination bonds, which not only enlarged the distance between pyrene cores to eliminate the aggregation-caused quenching (ACQ) effect but also obstructed the intramolecular motions of TBAPy to diminish the nonradiative relaxation, thus realizing a remarkable coordination-enhanced ECL. On the other hand, the ultrahigh porosity of Dy-TBAPy was beneficial to the diffusion of electrons, ions, and coreactant (S 2 O 8 2– ) in the skeleton, which efficiently boosted the excitation of interior TBAPy luminophores and led to a high utilization ratio of TBAPy, further improving ECL properties. More intriguingly, the ECL intensity of the Dy-TBAPy/S 2 O 8 2– system was about 4.1, 87.0-fold higher than those of classic Ru(bpy) 3 2+ /TPrA and Ru(bpy) 3 2+ /S 2 O 8 2– systems. Considering the aforementioned fabulous ECL performance, Dy-TBAPy was used as an ECL probe to construct a supersensitive ECL biosensor for microRNA-21 detection, which showed an ultralow detection limit of 7.55 aM. Overall, our study manifests that coordinatively assembling PAHs into MOFs is a simple and practicable way to improve ECL properties, which solves the ACQ issue of PAHs and proposes new ideas for developing highly efficient Ru-complex-free ECL materials, therefore providing promising opportunities to fabricate high-sensitivity ECL biosensors.