Enhanced electrochemiluminescent brightness and stability of porphyrins by supramolecular pinning and pinching for sensitive zinc detection
Ultrasensitive electrochemiluminescence (ECL) detection can benefit substantially from the rational configuration of emitter−enhancer stereochemistry. Here, using zinc(II) meso-5,10,15,20-tetra(4-sulfonatophenyl)porphyrin (ZnTSPP) as a model, we demonstrate that both the ECL intensity and the photostability of this emitter were significantly improved when it was trapped in pyridyl-bridged β-cyclodextrin dimer (Py(CD)2); a synthetic enhancer that is ECL inactive. Through NMR characterization, we confirmed that ZnTSPP formed a clam-like inclusion complex involving pinning and pinching forces from the biocompatible container Py(CD)2. Up to a threefold increase in the ECL brightness of ZnTSPP was witnessed when it was encapsulated in β-CD. Absorption and emission spectroscopic data revealed that both the extended excitation lifetime and the restricted mobility of the guest contributed to the observed improvement in signal transduction within the host molecule. This bioinspired entrapment also led to a marked boost in ECL stability. With the aid of the newly identified coreactant H2O2, the hollow TSPP@Py(CD)2 system was employed to create a Zn2+-selective probe that was capable of sensitive and accurate zinc detection. The observed increase in ECL conversion and enhanced photophysical properties of this compact supramolecular assembly render it a novel template for enhancing ECL in analytical applications.
KeywordsECL-active porphyrins Cyclodextrin dimer Host–guest inclusion Axial ligation Coreactant Zinc-specific sensor
This research was supported by the National Natural Science Foundation of China (grant nos. 21775072, 21874071), Outstanding Youth Foundation of Jiangsu Province (BK20170093), Qing Lan Project of Jiangsu Province, and the Fundamental Research Funds for the Central Universities (30916011201, 30916011204, 309171A8803). We express our appreciation to Dr. Yi Lu (Fasteur Biotechnology Corporation, Beijing) for kindly providing technical support for the instrumentation.
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Conflict of interest
The authors have no conflict of interest. This research did not involve any human participants or animals. All authors have been informed about this paper and consented to its publication.
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