PEGylation Improved Electrochemiluminescence Supramolecular Assembly of Iridium(III) Complexes in Apoferritin for Immunoassays Using 2D/2D MXene/TiO₂ Hybrids as Signal Amplifiers

Abstract

Dynamic self-assembly of iridium complexes in watersoluble nanocontainers is an important bottom-up process for fabricating electrochemiluminescence (ECL) bioprobes. PEGylated apoferritin (PEG-apoHSF) as the host offers a confined space to alter and modify the self-assembly of trans-bis(2-phenylpyridine)-(acetylacetonate)iridium(III) [Ir(ppy) 2 (acac)] based on a pH-dependent depolymerization/reassembly pathway, allowing the formation of ECL-active iridium cores in PEG-apoHSF cavities (Ir@PEG-apoHSF). With an improved encapsulation ratio in PEG-apoHSF, the coreactant ECL behavior of the fabricated Ir@PEG-apoHSF nanodots with tri-npropylamine (TPrA) was further demonstrated, exhibiting maximum ECL emission at 530 nm that was theoretically dominated by the band gap transition. The application of Ir@PEG-apoHSF as a bioprobe in a "signal-on" ECL immunosensing system was developed based on electroactive Ti 3 C 2 T x MXenes/TiO 2 nanosheet (Ti 3 C 2 T x /TiO 2 ) hybrids. Combining with the efficiently catalyzed electro-oxidation of TPrA and Ir(ppy) 2 (acac) by Ti 3 C 2 T x /TiO 2 hybrids, the developed immunosensor showed dramatically amplified ECL responses toward the target analyte of neuron-specific enolase (NSE). Under experimental conditions, linear quantification of NSE from 100 fg/mL to 50 ng/mL was well established by this assay, achieving a limit of detection (LOD) of 35 fg/mL. The results showcased the capability of PEGylated apoHSF to host and stabilize water-insoluble iridium complexes as ECL emitters for aqueous biosensing and immunoassays.

Ti3C2 MXene improved photoelectrochemical anode assembly of titanium dioxide nanoarrays for microcystin-LR detection

“…After the deposition of Ti 3 C 2 , its several diffraction peaks were found at 2 θ = 18.3°, 27.6°, 34.3°. 19 Moreover, other diffraction peaks of rutile TiO 2 were also found except for the (101) lattice plane, which can be explained by the incomplete oxidation of Ti 3 C 2 , after all, it is difficult to completely maintain its unstable structure during ultrasonic or heat treatment.…”

Aggregation-Induced Electrochemiluminescence Frame of Silica-Confined Tetraphenylethylene Derivative Matrixes for CD44 Detection via Peptide Recognition

“…To reduce nonradiative relaxation, researchers generally relied on schemes such as supramolecular assembly, the synthesis of TPE nanocrystals, and coordination induction-based metal–organic frameworks (MOFs) or coupling with other ligands. − Although signal amplification via tunable luminescence using the above-mentioned schemes has yielded satisfactory results, the quantitative encapsulation of AIECL molecules in a cavity carrier based on the effect of space limitation is a promising approach, especially when ECL emitter and sensing substrate are employed. This approach is in line with the use of novel ECL emitters for biosensing at the core of care, emphasizing the stability of labeled signal output …”

Rapid determination of SARS-CoV-2 nucleocapsid proteins based on 2D/2D MXene/P–BiOCl/Ru(bpy)32+ heterojunction composites to enhance electrochemiluminescence performance

“…For example, Yuan's group reports Ru-complex-grafted MXene nanosheets as an ECL indicator to fabricate ECL sensing platform for the tumor biomarker Mucin 1 (MUC1) [ 50 ]. Besides, Yang et al prepare electroactive and catalytic 2D/2D Ti 3 C 2 T x /TiO 2 hybrids to accelerate the electro-oxidation of TPA and Ir(ppy) 2 (acac), the developed immunosensor shows high ECL efficiency in the determination of neuron-specific enolase (NSE) [ 51 ]. Inspired by the above innovations, we speculate that MXene is a good scaffold for P–BiOCl, and the formation of rich terminating surface groups (i.e., =O, –OH, and –F) on MXene after exfoliation can help the P–BiOCl easily attach on MXene [ 40 , 52 , 53 ].…”