Xuwen Gao

Rapid and efficient detection of dopamine is crucial for disease prevention and clinical diagnosis. Herein, ZnCoP nanopolyhedra synthesized via a metal–organic framework (MOF)‐derived phosphidation route are employed as an electrocatalyst for electrochemical dopamine sensing. The constructed sensor exhibits outstanding analytical performance, featuring a wide linear range (0.5–1500 μM), high sensitivity (1038 μA mM ⁻¹ cm ⁻² ), and a low detection limit of 0.19 μM. Additionally, the sensor demonstrates excellent selectivity, long‐term stability, and reliable repeatability. The superior performance is attributed to the well‐defined polyhedral architecture inherited from the MOF precursor, which offers abundant electroactive sites and facilitates efficient electron transfer. These results establish ZnCoP nanopolyhedra as a promising sensing platform for dopamine detection, with strong potential for applications in medical diagnostics and bioanalytical monitoring.

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.

All of the commercialized electrochemiluminescence (ECL) immunoassays are automatically conducted at +1.40 V (vs Ag/AgCl) in the coreactant route. To alleviate the exogenous effect of coreactants and simplify the operation procedures, herein, a sulfur-vacancy-involved and free electron strategy is proposed to exploit Au nanoclusters (NCs) as anodic electrochemiluminophores and perform a coreactant-free immunoassay. The deficient coordination between the sulfhydryl of Met and the Au core might induce the departure of partial S atoms and enable Met-capped AuNCs (Met-AuNCs) with a sulfur-vacancy-involved electron-rich nature. The electron-rich nature tends to endow Met-AuNCs with unpaired endogenous free electrons, which can directly combine exogenous holes for light emitting. Coreactant-free ECL at around +0.86 V is consequently and conveniently achieved by merely oxidizing Met-AuNCs at the anode. The coreactant-free ECL is qualified to determine human carcinoembryonic antigen from 10 to 5000 pg/mL with a limit of detection of 5 pg/mL. Electron paramagnetic resonance provides clear evidence that endogenous free electrons within Met-AuNCs play an important role in the generation of coreactant-free ECL. This sulfur-vacancy-involved and free electron strategy is promising for designing nanoelectrochemiluminophores with improved immunoassay performance.

Chemiluminescence (CL), especially commercialized CL immunoassay (CLIA), is normally performed within the eye-visible region of the spectrum by exploiting the electronic-transition-related emission of the molecule luminophore. Herein, dual-stabilizers-capped CdTe nanocrystals (NCs) is employed as a model of nanoparticulated luminophore to finely tune the CL color with superior color purity. Initialized by oxidizing the CdTe NCs with potassium periodate (KIO₄), intermediates of the reactive oxygen species (ROS) tend to charge CdTe NCs in both series-connection and parallel-connection routes and dominate the charge-transfer CL of CdTe NCs. The CdTe NCs/KIO₄ system can exhibit color-tunable CL with the maximum emission wavelength shifted from 694 nm to 801 nm, and the red-shift span is over 100 nm. Both PL and CL of each of the CdTe NCs are bandgap-engineered; the change in the NCs surface state via CL reaction enables CL of each of the CdTe NCs to be red-shifted for ∼20 nm to PL, while the change in the NCs surface state via labeling CdTe NCs to secondary-antibody (Ab₂) enables CL of the CdTe NCs-Ab₂ conjugates to be red-shifted for another ∼20 nm to bare CdTe NCs. The CL of CdTe753-Ab₂/KIO₄ is ∼791 nm, which can perform near-infrared CL immunoassay and semi-automatically determined procalcitonin (PCT) on commercialized in vitro diagnosis (IVD) instruments.

A low-triggering potential and a narrow-potential window are anticipated to decrease the electrochemical interference and cross talk of electrochemiluminescence (ECL). Herein, by exploiting the low oxidative potential (0.82 V vs Ag/AgCl) of dihydrolipoic acid-capped sliver nanoclusters (DHLA-AgNCs), a coreactant ECL system of DHLA-AgNCs/hydrazine (N₂H₄) is proposed to achieve efficient and oxidative-reduction ECL with a low-triggering potential of 0.82 V (vs Ag/AgCl) and a narrow-potential window of 0.22 V. The low-triggering-potential and narrow-potential-window nature of ECL can be primarily preserved upon labeling DHLA-AgNCs to probe DNA and immobilizing DHLA-AgNCs onto the Au surface via sandwiched hybridization, which eventually enables a selective ECL strategy for the gene assay at +0.82 V. This gene assay strategy can sensitively determine the gene of human papillomavirus from 10 to 1000 pM with a low limit of detection of 5 pM (S/N = 3) and would open a way to improve the applied ECL bioassay.

The low-triggering-potential and potential-selective electrochemiluminescence for a highly selective immunoassay by exploiting AgInS ₂ /ZnS nanocrystals as a tag and N ₂ H ₄ as a coreactant.