Bis-tridentate Iridium(III) Complex with the N-Heterocyclic Carbene Ligand as a Novel Efficient Electrochemiluminescence Emitter for the Sandwich Immunoassay of the HHV-6A Virus.

Human herpesvirus type 6A (HHV-6A) can cause a series of immune and neurological diseases, and the establishment of a sensitive biosensor for the rapid detection of HHV-6A is of great significance for public health and safety. Herein, a bis-tridentate iridium complex (BisLT-Ir-NHC) comprising the N-heterocyclic carbene (NHC) ligand as a novel kind of efficient ECL luminophore has been unprecedently reported. Based on its excellent ECL properties, a new sensitive ECL-based sandwich immunosensor to detect the HHV-6A virus was successfully constructed by encapsulating BisLT-Ir-NHC into silica nanoparticles and embellishing ECL sensing interface with MXene@Au-CS. Notably, the immunosensor illustrated in this work not only had a wide linear range of 102 to 107 cps/µL but also showed outstanding recoveries (98.33-105.11%) in real human serum with an RSD of 0.85-3.56%. Undoubtedly, these results demonstrated the significant potential of the bis-tridentate iridium(III) complex containing an NHC ligand in developing ECL-based sensitive analytical methods for virus detection and exploring novel kinds of efficient iridium-based ECL luminophores in the future.

Ultrasensitive Electrochemiluminescence Biosensor to Detect Ampicillin Resistance Gene (ARGAMP) Based on a Novel Near-Infrared Ruthenium Carbene Complex/TPrA/PEI Ternary ECL System.

The establishment of rapid target identification and analysis methods for antibiotic resistance genes (ARGs) is urgently needed. In this study, we unprecedently designed a target-catalyzed hairpin assembly (CHA) electrochemiluminescent (ECL) biosensor for the ultrasensitive detection of ampicillin resistance genes (ARGAMP) based on a novel, efficient near-infrared ruthenium carbene complex/TPrA/PEI ternary ECL system with low oxidation potential. The ternary NIR-ECL system illustrated in this work displayed double ECL intensity in comparison with their corresponding traditional binary ECL system. The as-prepared ECL biosensor illustrated in this work demonstrates highly selective and sensitive determination of ARGAMP from 1 fM to 1 nM and a low detection limit of 0.23 fM. Importantly, it also exhibits good accuracy and stabilities to identify ARGAMP in plasmid and bacterial genome DNA, which demonstrates its excellent reliability and great potential in detecting ARGAMP in real environmental samples.

Novel Electrochemiluminescent Biosensor to Ultrasensitively Detect U94 Gene in Human Herpesvirus 6 Using Metal-Organic Framework-Based Nanoemitters Comprising Iridium(III) Complexes via One-Pot Coordination Reaction Strategy.

The detection of the U94 gene in human herpesvirus 6 is crucial for early diagnosis of HHV-6 infections, which could induce acute febrile illness in infants. In this work, the first ultrasensitive electrochemiluminescence (ECL) biosensor for detecting U94 gene in Human Herpesvirus 6 was successfully designed by utilizing efficient novel metal-organic framework (MOF)-based ECL nanoemitters comprising iridium(III) complexes (Ir-ZIF-8-NH2) synthesized via one-pot coordination reaction strategy as an ECL indicator and a target-catalyzed hairpin assembly (CHA) signal amplification strategy. The as-prepared ECL indicator Ir-ZIF-8-NH2 exhibited an approximately 2.7-fold ECL intensity compared with its small molecular analogue of emissive iridium(III) complex named IrppymIM formed by in situ coordination reaction between iridium(III) solvent complex and imidazole ligands. In addition, a target-catalyzed hairpin assembly (CHA) strategy was employed to further improve the sensitivity of the proposed ECL biosensor, which demonstrated a wide linear range from 1 fM to 1 µM and the limit of detection as low as 0.113 fM (S/N = 3). Significantly, this biosensor was successfully applied to detect U94 gene in plasmids and real virus samples. The recoveries were in the range of 97.0-109.0% for plasmids and 95.7-107.5% for real virus samples with a relative standard deviation (RSD) of 1.87-2.53%. These satisfactory experimental results from the proposed ECL biosensor in this work would inevitably promote the development of new time/cost-effective and sensitive methods to detect HHV-6 with a major global health threat and substantial burden on healthcare in the future.

A novel efficient intramolecular self-enhanced water-soluble iridium-based electrochemiluminescence reagent and its analytical application in aptamer sensor.

In order to overcome the poor solubilities of iridium-based ECL luminophores and explore self-enhanced ECL luminophores, polyethyleneimine (PEI) covalently linked with iridium complex via amide bonds (abbreviated as Ir-PEI) as a new novel intramolecular self-enhanced water-soluble ECL reagent has been unprecedently designed and successfully synthesized in this work. The chemical structure data, FT-IR spectra, photophysical, electrochemical and electrochemiluminescence of this new ECL reagent have been well characterized. In addition, in order to investigate its properties in the real applications, a corresponding new sensitive and specific ECL-based aptasensor to monitor tetracycline (TET) residues in honey and lake water has been further constructed based on this novel self-enhanced reagent of Ir-PEI in this work. This as-prepared intramolecular self-enhanced water-soluble of Ir-PEI illustrated in this work would pave a new avenue to promote the analytical applications of iridium-based ECL luminophores in the future.

Singlet Oxygen Generation via an Electrochemical Reduction Method Assisted by a Ruthenium(II) Complex.

In this work, singlet oxygen (1O2) is unprecedently recorded in the electrochemical reduction of tris(2,2'-bipyridine)ruthenium(II) [Ru(bpy)32+] in an acetonitrile solution with dissolved oxygen, which is well characterized by the specific probe of Singlet Oxygen Sensor Greens and the technique of electron-spin resonance in this work. Importantly, this new electrochemical method to produce 1O2 shows higher efficiency than the conventional photodriven method. Furthermore, taken together with the inherent advantages of electrochemical techniques compared with the photochemical/chemical-driven method, this electrochemical method would inevitably show great promise in reactive-oxygen-species-related studies in the future.

Iridium tetrazolato complexes as efficient protein staining agents.

In this work, three iridium(III) tetrazolato complexes have been designed and successfully synthesized. Beside photophysical properties, their performances in protein staining have been comprehensively investigated in this work for the first time. Notably, these iridium(III) tetrazolato complexes with high quantum efficiency exhibited much better protein staining properties than the commercial agent Coomassie Brilliant Blue (CBB) under the same experimental conditions, which may pave the way to explore new efficient iridium-based protein staining agents both for commercial markets and academic research in the future.