Aggregation-Induced Electrochemiluminescence Bioconjugates of Apoferritin-Encapsulated Iridium(III) Complexes for Biosensing Application.

An intriguing aggregation-induced electrochemiluminescence (AIECL) bioconjugate was fabricated by encapsulating fac-tris(2-phenylpyridine)iridium(III) complexes [Ir(ppy)3] in the apoferritin (apoFt) cavity for biosensing application. Based on the unique pH-dependent disassembly/reassembly characteristic of apoFt, approximately 44.3 molecules of Ir(ppy)3 aggregated in the single cavity through both intermolecular π-π-stacking interactions and hydrogen bonds that efficiently restricted the intramolecular motions to trigger the AIECL effect. Compared to monomers, Ir(ppy)3 aggregates performed 5.3-fold-enhanced ECL emission using tri-n-propylamine (TPrA) as a coreactant. The fabricated Ir(ppy)3@apoFt bioconjugate was flexibly labeled with a detection antibody to act as a transducer for the immunosensor construction. To further catalyze the ECL reaction between the reductive TPrA• and the oxidative Ir(ppy)3+• radicals, a conductive and electroactive substrate of Fe2N and gold nanoparticle-codecorated reduced graphene oxide (Fe2N/rGO/Au) was established to incubate the capture antibody. Therefore, a "signal on" immunosensor was developed for sensitive assay of cytokeratin 19 fragment 21-1 (CYFRA 21-1), in which good linearity ranging from 1 pg/mL to 50 ng/mL with a low detection limit of 0.43 pg/mL (S/N = 3) was obtained. This study shares with an inspiration of using apoFt to design iridium(III)-based AIECL emitters, which will expand more possibilities of organic iridium(III) complexes in establishing innovative ECL immunoassays.

Citation

Lei Yang, Xu Sun, Dong Wei, Huangxian Ju, Yu Du, Hongmin Ma, Qin Wei. Aggregation-Induced Electrochemiluminescence Bioconjugates of Apoferritin-Encapsulated Iridium(III) Complexes for Biosensing Application. Analytical chemistry. 2021 Jan 26;93(3):1553-1560

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PMID: 33347268

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