Guizheng Zou

Nanoluminophores are promising candidates for monochromatic emission; however, the commercial and quantitative applications of nanoluminophores are hindered by their undefined molar mass, limited storage stability, and lack of reproducibility in fabrication. Here, we propose a 1,4-boron–nitrogen (1,4-BN)-embedded multiresonance structure (CzBNs) to design molecular luminophores with electrochemiluminescence (ECL) emission tunable in waveband and monochromaticity, which is comparable to the ECL luminophores of deliberately designed nanomaterials and superior to the commercial ECL luminophores based on conventional molecules. Moreover, the molecular luminophore CzBN-Ph–COOH can be utilized as an ECL tag in a sandwich-type immunosensor to accurately determine carcinoembryonic antigen (CEA) at the 10 pg/mL level without the inherent limitations of nanomaterials.

Near-infrared (NIR) electrogenerated chemiluminescence (ECL) offers superior tissue penetration and reduced background for bioimaging, yet stable, efficient NIR luminophores remain rare. This study investigates the photophysical dynamics and ECL mechanisms of two donor–acceptor–donor platinum–acetylide oligomers, Pt2DTB and Pt2BTDEDOT. Using femtosecond transient absorption spectroscopy, we identify an ultrafast intersystem crossing process (τISC ≈ 0.5–1.2 ps) driven by strong spin–orbit coupling, which establishes a robust triplet reservoir. Temperature-dependent TRPL and oxygen-quenching measurements support a triplet-mediated delayed-emission channel, while density functional theory calculations reveal large singlet–triplet energy gaps, ΔEST > 0.6 eV, that disfavor efficient TADF. These observations are consistent with a Singlet-Initiated ISC–Triplet pathway involving Triplet–Triplet Annihilation (SIT–TTA). While electrochemical analysis shows that the radical anions of these oligomers are unstable, leading to weak annihilation ECL, the use of tripropylamine (TPrA) as a coreactant bypasses this instability, enhancing ECL intensity by 2–3 orders of magnitude. The resulting emission is significantly red-shifted, indicating a stabilized lower-energy emissive manifold. These findings provide critical design principles for organometallic NIR emitters, demonstrating that coreactant strategies are essential for leveraging triplet reservoirs in high-sensitivity optoelectronics.

Nanoparticles (NPs) are alternative chemiluminescence (CL) luminophores to molecular luminophores and are strongly anticipated to extend molecular luminophore-tagged commercial CL immunoassays (CLIA) with wavebands beyond the eye-visible region and sensitivity beyond the pg/mL level. Herein, a surficial bond-involved repetitive excitation strategy for near-infrared CL with enhanced photons per luminophore is proposed by exploiting l-methionine (l-Met)-capped gold NPs (AuNPs) as luminophores. The surficial Au–S bonds of l-Met@AuNPs can be involved in the procedure of NP core excitation via oxidation, and bring out defect-involved CL around 830 nm. Because there are plenty of Au–S bonds on every AuNP core, l-Met@AuNPs can be repetitively excited over a hundred times and give off greatly enhanced CL photons per luminophore than all molecular CL luminophores. CL of l-Met@AuNPs/(NH₄)₂S₂O₈ can directly enable automatic near-infrared CLIA for myoglobin (MYO) determination on in vitro diagnostic instruments, with a limit of detection of 10 fg/mL (S/N = 3), which significantly surpasses the threshold of molecular luminophores. This Au–S bond-triggered AuNP CL strategy not only offers an alternative to molecular CL strategies with improved sensitivity and to II–VI NP CL strategies with fewer toxic concerns, but also indicates that exploiting the surficial bond energy of NPs could be an alternative to designing NPs with unique morphology, structure, and composition in the CL domain.

Quantum dots (QDs) are attractive electrochemiluminescence (ECL) luminophores because of their quantum confinement and tunable band structures; however, QD-based ECL is often limited by low efficiency and inadequate operational stability. Here, low-toxic CuInS₂ QDs (CIS) are assembled into an aerogel through a facile in situ gelation strategy to enhance ECL emission. The aerogel architecture strengthens interparticle electronic coupling, lowers the interparticle charge-transfer barrier, and facilitates charge separation and transport. As a result, the CIS aerogel delivers a 76-fold enhancement in ECL intensity compared with individual CIS QDs. Notably, the in situ gelation strategy is scalable, producing 0.54 g of CIS aerogel per batch, which supports practical use in ECL sensing. As a proof-of-concept, the CIS aerogel is integrated into an ECL immunosensor for carcinoembryonic antigen (CEA), affording a satisfactory linear range of 1 pg mL^-1 to 100 ng mL^-1 and a detection limit of 0.34 pg mL^-1 (S/N = 3). The immunosensor also exhibits excellent selectivity and reproducibility. This work highlights interparticle charge transport as an effective lever for boosting QD-based ECL and underscores the potential of QD aerogels for advanced ECL biosensing.

The unary nanocrystals (NCs) of copper are frequently employed as a catalyst, sensitizer, and energy transfer mediator of chemiluminescence (CL). Herein, the direct and defect-involved CL of copper NCs (CuNCs) for the semiautomatic immunoassay is proposed with bovine serum albumin (BSA)-stabilized CuNCs (BSA-CuNCs) as luminophores. The biocompatible BSA-CuNCs are a kind of n-type NC that can directly give off flash CL via charge annihilation between its endogenous electrons and exogenously injected holes by the coexisting oxidative activators. Potassium hexacyanoferrate(III) (K₃[Fe(CN)₆]) can trigger BSA-CuNCs with efficient CL around ∼701 nm, a waveband longer than all commercial-available CL reagent kits. The coexisting citric ion can also directly reduce the hole-injected BSA-CuNCs to further enhance CL emission. The CL of BSA-CuNCs/K₃[Fe(CN)₆] in citrate buffer is consequently utilized to detect myoglobin on the commercialized and semiautomatic IVD device, which exhibits improved determination performance compared to the commercially available CL reagent kits, with a wide linear response range from 0.25 to 1000 pg/mL and a limit of detection of 0.10 pg/mL (S/N = 3). BSA-CuNCs can be safely stored in pure water and label protein without unintended precipitation, which might provide an alternative to the molecule tagged CL reagent kits.

Schematic illustration of 1690-fold enhanced electrochemiluminescence of gold nanoclusters via Zn ²⁺ induced aggregation.

Amide bonds are most frequently utilized to form the bioconjugates of nanoclusters (NCs) and biomolecules; however, the amide bonds involved in the bioconjugation process tend to dramatically alter the functional group of NCs, decrease storage stability, and eventually block their practical bioapplication. With N-acetyl-l-cysteine (NAC)-capped AuNCs (NAC-AuNCs) as a model, we propose a biocompatible electrochemiluminescence (ECL) luminophore with thiol as a stabilizer and bioconjugate anchor. The NAC-AuNCs can exhibit a solely oxidative-reduction ECL process around +0.94 V with a maximum emission wavelength of around 824 nm. By immobilizing SH-modified probe hepatitis B virus (HBV) DNA (p-DNA) onto NAC-AuNCs via Au-S bonds, NAC-AuNCs can be used as ECL tags for gene assays with thiol as the anchor of bioconjugates, which provides an alternative to conventional bioconjugates and proves that ECL reagent kits can be developed in a 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide hydrochloride (EDC)-free way. The NIR ECL of NAC-AuNCs can be utilized to linearly determine HBV from 10 pM to 5 nM with a limit of detection (LOD) of 5 pM (S/N = 3). Notably, NAC-AuNCs can be safely stored for over four months without signal attenuation and can link the SH-modified gene without permanent precipitation.

The commercialized immunoassay of glow-type chemiluminescence (CL) is always performed in an enzyme-assisted and indirect CL way, with molecular luminophores as tags. Herein, dual-stabilizer-capped Au nanoclusters (NCs) are proposed as nanoparticulate glow-CL luminophores and perform automatic immunoassays on commercialized in vitro diagnosis (IVD) instruments in a direct and enzyme-free CL way. The thiosalicylic acid (TSA) and bovine serum albumin (BSA) stabilized AuNCs (TSA/BSA-AuNCs) are water-soluble, biocompatible, and n-type CL luminophores, which can give off dark-red and glow-type CL with the coexistence of both hydrazine hydrate (N₂H₄·H₂O) and hydrogen peroxide (H₂O₂). The glow-CL of TSA/BSA-AuNCs is generated in a combined route of bandgap-engineered CL (∼711 nm) and surface-defect-engineered CL (∼860 nm), and its total emission is strong enough to linearly determine procalcitonin (PCT) from 0.1 to 5000 pg/mL with a limit of detection of 0.05 pg/mL (S/N = 3), which is superior to the limit of detection for all of the commercialized CL immunoassays. Promisingly, TSA/BSA-AuNCs can be safely stored over 5 months and safely labeled to proteins without permanent precipitation and damage, which are strongly anticipated for the design of CL reagent kits with nanoparticles as tags and might initiate the commercialized application of NCs CL.

Mechanism study of dual ECL of p-PtBTD, driven by singlet and triplet excited states through RISC and TTA pathways.