Graphitic-phase carbon nitride-based electrochemiluminescence sensing analyses: recent advances and perspectives

Abstract

Graphitic-phase carbon nitride (g-C₃N₄) materials are important polymeric and metal-free semiconductors, and have attracted extensive attention as emerging electrochemiluminescence (ECL) emitters due to their wonderful optical and electronic properties. The g-C₃N₄-based ECL sensing analysis, as a research hotspot in analytical chemistry, offers an exquisite pathway to monitor target analytes with the advantages of low background signal, high sensitivity, desirable controllability, and simple instrumentation. Herein, we briefly describe the current research status of g-C₃N₄-based ECL assays along with versatile signaling strategies, introduce the preparation methods and ECL emission mechanisms of g-C₃N₄-dependent emitters, summarize their ECL sensing applications from 2012 to now, highlighting with special examples of metal ion and small molecule detection, nucleic acid bioanalysis, immunoassay, protein sensing, and cell-related determination. Finally, the prospects and challenges for future work are also explored to design more advanced ECL biosensors.

Fig. 1. (A) Triazine and (B) tri-s-triazine as the basic structural units of g-C₃N₄. Reproduced from ref. 34 with permission from The American Chemical Society.

Fig. 2. Overview of g-C₃N₄-based materials for ECL sensing analysis.

Fig. 3. The preparation of DSP-decorated Au–g-C₃N₄ for highly selective ECL detection of DA based on dual-molecular recognition and PANI quenching. Reproduced from ref. 54 with permission from Elsevier.

Fig. 4. (A) The ECL responses of g-C₃N₄ NFF modified GCE in 0.1 M (a) air-saturated PBS of pH 7.0, nitrogen-saturated PBS of pH 7.0 containing (b) 0.258 mM H₂O₂ and (c) 0.258 mM K₂S₂O₈, and (B) the cathodic ECL emission mechanism for g-C₃N₄ NFF/R-O coreactant systems. Reproduced from ref. 63 with permission from The Royal Society of Chemistry.

Fig. 5. (A) The electronic band structure of CNNS and oxidation/reduction potentials of different metal ions; (B) the proposed ECL reaction pathways of CNNS in the presence of Ni²⁺; (C) ECL intensity of CNNS-modified GCE with different Ni²⁺ concentrations in the presence of K₂S₂O₈ at cathodic potential range and TEA at anodic potential range; and (D) the linear fitting of cathodic and anodic ECL quenching coefficients. Reproduced from ref. 68 with permission from The American Chemical Society.

Fig. 6. (A) The typical reaction path for the formation of full condensed CN; (B) the process of exfoliating CN-T (T = 400, 450, 500, 550, 600, 650); (C) TEM of (a) CNNS-400, (b) CNNS-500, and (c) CNNS-650. (d) XRD spectra of CNNS-650 and CN-650; and (D) ECL responses of (a) CNNS-500, (b) CNNS-650, and (c) CNNS-400 with various metal-ions at the cathodic potential range. Inset: calibration curves for monitoring (a) Ni²⁺, (b) Cd²⁺, and (c) Cu²⁺. Reproduced from ref. 76 with permission from The American Chemical Society.

Fig. 7. (A) The synthesis procedure of g-C₃N₄–CD–Fc-COOH. (B) Schematic diagram of the construction and response mechanism of ECL biosensor for OPs assay. Reproduced from ref. 79 with permission from The Royal Society of Chemistry.

Fig. 8. The ratiometric ECL biosensor for glucose detection by means of in situ production and conversion of coreactants caused by catalytic cascade reactions of GOx/Au–g-C₃N₄. Reproduced from ref. 81 with permission from Elsevier.

Fig. 9. Schematic diagram of a novel dual-wavelength ratiometric ECL-RET biosensor for the detection of microRNA. Reproduced from ref. 84 with permission from The American Chemical Society.

Fig. 10. (A) The general fabrication of m-CNNS based on simultaneous noncovalent modification and exfoliation process, and (B) the construction of ECL DNA biosensor using m-CNNS, and conventional CNNS as a control. Reproduced from ref. 85 with permission from The American Chemical Society.

Fig. 11. Schematic illustration of (A) the preparation process of multi-functionalized g-C₃N₄, and (B) the construction of proposed immunosensor for CA125 detection. Reproduced from ref. 87 with permission from Elsevier.

Fig. 12. The spatial-resolved ECL ratiometry for sensitive monitoring of PSA based on a closed BPE. Reproduced from ref. 91 with permission from Elsevier.

Fig. 13. Schematic illustration of (A) the novel permeability gate-mediated ECL aptasensors by means of target-responsive polyelectrolyte-aptamer films (reproduced from ref. 93 with permission from The Royal Society of Chemistry), and (B) the synthetic process of 3D-GR-AuNPs for the preparation of ECL biosensor (reproduced from ref. 95 with permission from Elsevier).

Fig. 14. The construction of a dual-potential ratiometric ECL biosensor for the monitoring CTCs and evaluating their surface glycan. Reproduced from ref. 99 with permission from Elsevier.

Jingjing Jiang

Xinyi Lin

Dong Ding

Guowang Diao