Low-Triggering-Potential and Narrow-Potential-Window Electrochemiluminescence of Silver Nanoclusters for Gene Assay

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.

Silver Nanocluster-Tagged Electrochemiluminescence Immunoassay with a Sole and Narrow Triggering Potential Window

The commercialized electrochemiluminescence (ECL) immunoassay is carried out by holding luminophore Ru(bpy)32+ at a given potential. Designing an electrochemiluminophore with a narrow triggering potential window is strongly anticipated to decrease the electrochemical cross-talk and improve the flux of the commercialized ECL immunoassay in a potential-resolved way. Herein, L-penicillamine-capped silver nanoclusters (LPA-AgNCs) are facilely synthesized and utilized as tags to perform the ECL immunoassay with a sole and narrow triggering potential window of 0.24 V by employing hydrazine (N2H4) as a coreactant. The maximum ECL emission of the LPA-AgNCs/N2H4 system is located ca. +1.27 V. Upon immobilizing LPA-AgNCs onto the electrode surface via forming a sandwich immunocomplex, the ECL of LPA-AgNCs/N2H4 can be utilized to sensitively and selectively determine human carcinoembryonic antigen from 0.5 to 1000 pg/mL with a low limit of detection of 0.1 pg/mL (S/N = 3). This work might open a way to screen electrochemiluminophores for the multiple ECL immunoassay in a potential-resolved way.

Intrareticular Charge Transfer Triggered Self-Electrochemiluminescence of Zirconium-Based Metal-Organic Framework Nanoparticles for Potential-Resolved Multiplex Immunoassays with Isolated Coreactants

In this work, a potential-resolved electrochemiluminescence (ECL) multiplex immunoassay (MIA) was developed using zirconium-based metal-organic framework (MOF) nanoparticles with intense self-ECL as an anodic ECL tag and CdTe nanocrystals (NCs) as a cathodic ECL tag. ECL luminophore 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H₄ADIP) and coreactant hexamethylenetetramine (HMT) bound to zirconium nodes in the MOF, giving Zr-ADIP-HMT nanoparticles. Benefiting from the intrareticular charge transfer (ICT) between the oxidized ligands of H₄ADIP and HMT via hydrogen bonds, the intense self-ECL from Zr-ADIP-HMT was applied to the potential-resolved ECL MIA without an exogenous anodic coreactant, which can eliminate detrimental effects of multiplex coreactants and anodic ECL emission from CdTe NCs. The ICT within Zr-ADIP-HMT nanoparticles could shorten the electron transport path and reduce the complexity of radical intermediate transport. The ECL intensity from Zr-ADIP-HMT was 18.6-fold that from the mixture of H₄ADIP and HMT. In potential-resolved ECL MIA, two lung cancer biomarkers, carcinoembryonic antigen and neuron-specific enolase, were adopted as model analytes, with detection limits of 18 and 5.3 fg·mL^-1, respectively. The dual-ligand Zr-ADIP-HMT nanoparticles provide a proof of concept using ICT-based self-ECL luminophores for potential-resolved ECL MIAs with isolated coreactants.

Dual-potential encoded electrochemiluminescence for multiplexed gene assay with one luminophore as tag

Multiplexed gene assay for simultaneously detecting the multi-targets of nucleic acids is strongly anticipated for the accurate diseases diagnosis and prediction, and all commercial available gene assays for IVD are a kind of single-target assay. Herein, a dual-potential encoded and coreactant-free electrochemiluminescence (ECL) strategy is proposed for the multiplexed gene assay, which can be conveniently carried out by directly oxidizing the same luminescent tag of dual-stabilizers-capped CdTe nanocrystals (NCs). The CdTe NCs linked with sulfhydryl-RNA via Cd-S bond merely exhibits one ECL process around 0.32 V with a narrow triggering-potential-window of 0.35 V, while CdTe NCs linked with amino-RNA via amide linkage solely gives off one ECL process around 0.82 V with a narrow triggering-potential-window of 0.30 V. Multiplexing ECL of both sulfhydryl-RNA-functionalized CdTe NCs and amino-RNA-functionalized CdTe NCs can be utilized to simultaneously detect the open reading frame 1ab (ORF1ab) and the nucleoprotein (N) genes without crosstalk, in which ECL of sulfhydryl-RNA-functionalized CdTe NCs can dynamically determine ORF1ab from 200 aM to 10 fM with a limit of detection (LOD) of 100 aM, while ECL of amino-RNA-functionalized CdTe NCs can linearly detect N gene from 5 fM to 1 pM with a LOD of 2 fM. Post-engineering CdTe NCs with RNA in a labeling-bond engineering way would provide a potential-selective and encoded ECL strategy for multiplexed gene assay with one luminophore.

Enhanced Photon Emission of Chemiluminescent Luminophore for Ultra-Fast and Semi-Automatic Immunoassay toward Single Molecule Detection

Optical single molecule detection is normally achieved via amplifying the total emission of photons of luminophores and is strongly anticipated to extend the commercialized application of chemiluminescence (CL). To overcome the limited CL photons of molecule luminophores, herein, a nanocrystal (NC) luminophore self-amplified strategy is proposed to repetitively excite CL luminophores for amplifying the total CL photons per luminophore, which can be exploited to perform CL immunoassays (CLIAs) toward single molecule detection via employing KMnO₄ as the CL triggering agent and the dual-stabilizer-capped CdTe NCs as the CL luminophore. KMnO₄ can oxidize the S element from each stabilizer of mercaptopropionic acid (MPA) and release enough energy to excite the CdTe core for flash CL. The substantial MPA around each CdTe core enables every CdTe luminophore to be repetitively excited and give off amplified total CL photons in a self-enhanced way. The CL of CdTe NCs/KMnO₄ can release all photons rapidly, and the collection of all these photons can be utilized to determine the model analyte of thyroid-stimulating hormone antigen (TSH) with a limit of detection of 5 ag/mL (S/N = 3), which is corresponding to about 2-4 TSH molecules in a 20 μL sample. The whole immunologic operating process can be terminated within 6 min. This strategy of repetitively breaking the CL reaction involving chemical bonds within one luminophore is promising for semi-automatic as well as fully automatic single molecule detection and extends the commercialized application of CL immunodiagnosis.

Luminophore-Surface-Engineering-Enabled Low-Triggering-Potential and Coreactant-Free Electrochemiluminescence for Protein Determination

Coreactant-free electrochemiluminescence (ECL) is promising for removing the exogenous effects of coreactant and simplify the operation procedures and setups of commercialized ECL bioassays. Herein, an electrosterically involved strategy for achieving a low-triggering-potential (+0.21 V vs Ag/AgCl) and coreactant-free ECL from dual-stabilizer-capped CdTe nanocrystals (NCs) is proposed with mercaptopropionic acid (MPA) and hexametaphosphate (HMP) as the capping agents of luminophores. Upon employing the CdTe NCs as the ECL tag for the immunoassay, all the tags in the bioconjugates of the CdTe NCs and the secondary antibody (Ab₂|CdTe) as well as in the final achieved sandwich-type immunocomplexes can exhibit efficient coreactant-free ECL with an electrosterically involved triggering potential nature. The bioconjugates of Ab₂|CdTe with Ab₂ no more than 30 kDa, such as the thyroid stimulating hormone (30 kDa) and the recombinant pro-gastrin releasing peptide (ProGRP, 14 kDa), merely exhibit coreactant-free ECL around +0.24 V, while bioconjugates of Ab₂|CdTe with an Ab₂ beyond 30 kDa only give off coreactant-free ECL around +0.82 V. Due to the further enhanced electrosteric effect in sandwich-type immunocomplexes, only the ECL immunosensor with ProGRP as the target can give off coreactant-free ECL around +0.24 V. The electrosterically involved and coreactant-free ECL of CdTe NCs is consequently utilized to sensitively and selectively determine the molecular protein ProGRP, which demonstrates a wide linearity range from 0.1 to 2000 pg/mL and a low limit of detection at 0.05 pg/mL (S/N = 3). This low-triggering-potential and coreactant-free combined ECL platform indicates that engineering the surface of CdTe NCs with a protein can improve the performance of ECL tags in a protein-weight-involved electrosterical way.

Surface-Defect-Involved and Eye-Visible Electrochemiluminescence of Unary Copper Nanoclusters for Immunoassay

A single-stabilizer-capped strategy is proposed for achieving highly efficient and surface-defect-involved electrochemiluminescence (ECL) from unary copper nanoclusters (NCs) via employing l-cysteine (Cys) as a capping agent of luminophore. The Cys-capped CuNCs (Cys-CuNCs) can be electrochemically injected with valence band (VB) holes and exhibit eye-touchable ECL processes around +0.95 and +1.15 V upon employing TPrA as a coreactant. Both accumulated ECL spectra and spooling ECL spectra demonstrated that the two ECL processes are of the same single waveband and spectrally identical to each other with the same maximum emission wavelength of 640 nm. Promisingly, ECL of the Cys-CuNCs/TPrA system is obviously red-shifted for ∼150 nm to PL of Cys-CuNCs, indicating that the bandgap-engineered routes for ECLs of Cys-CuNCs are completely blocked. The oxidative-reduction ECL process of the Cys-CuNCs/TPrA system is a kind of highly efficient, eye-visible, and single-color emission in surface-defect-involved route. The capping agent of Cys can enable the CuNCs/TPrA system with a stronger ECL than other thiol capping agents, so that Cys-CuNCs are utilized as ECL tags for sensitive and selective immunoassays, which exhibit a wide linear response range from 0.05 pg/mL to 0.5 ng/mL and a limit of detection of 0.01 pg/mL (S/N = 3) with carcinoembryonic antigen as the analyte. Moreover, both the luminophore Cys-CuNCs and conjugates Ab₂-CuNCs can be safely stored in aqueous media without any protector, which is promising for the evolution and clinic application of metal NC ECL in the surface-defect-involved route.

Valence-State-Engineered Electrochemiluminescence from Au Nanoclusters

To determine the intrinsic effects of body elements on the electrochemiluminescence (ECL) of metal nanoclusters (NCs), herein, a valence-state engineering strategy is developed to adjust the NCs' ECL with bovine serum albumin (BSA)-stabilized AuNCs as a model, in which engineering the valence state of the Au body element, i.e., Au(0) and Au(I), is performed via successively reducing the precursor AuCl₄^- to Au(I) and Au(0) with BSA. The obtained BSA-AuNCs/N₂H₄ system leads to three anodic ECL processes at 0.37 (ECL-1), 0.85 (ECL-2), and 1.45 V (ECL-3). ECL-1 is generated from the BSA-Au(0) section of BSA-AuNCs in a surface-defect-involved route and is much stronger and red-shifted compared to ECL-2 and ECL-3, which are generated from the BSA-Au(I) section of BSA-AuNCs in the band-gap-engineered route. Each of the anodic ECL processes can be selectively generated and/or suppressed via adjusting the Au(I)/Au(0) ratio of BSA-AuNCs, tunable ECL generation route, and triggering potential, and the emission intensity and waveband of metal NCs are conveniently achieved in body-element-involved valence-state engineering.

Interparticle Charge-Transport-Enhanced Electrochemiluminescence of Quantum-Dot Aerogels

Electrochemiluminescence (ECL) represents a widely explored technique to generate light, in which the emission intensity relies critically on the charge-transfer reactions between electrogenerated radicals. Two types of charge-transfer mechanisms have been postulated for ECL generation, but the manipulation and effective probing of these routes remain a fundamental challenge. Here, we demonstrate the design of quantum dot (QD) aerogels as novel ECL luminophores via a versatile water-induced gelation strategy. The strong electronic coupling between adjacent QDs enables efficient charge transport within the aerogel network, leading to the generation of highly efficient ECL based on the selectively improved interparticle charge-transfer route. This mechanism is further verified by designing CdSe-CdTe mixed QD aerogels, where the two mechanistic routes are clearly decoupled for ECL generation. We anticipate our work will advance the fundamental understanding of ECL and prove useful for designing next-generation QD-based devices.

Pathogen Identification: Ultrasensitive Nucleic Acid Detection via a Dynamic DNA Nanosystem-Integrated Ratiometric Electrochemical Sensing Strategy

Sensitively determining trace nucleic acid is of great significance for pathogen identification. Herein, a dynamic DNA nanosystem-integrated ratiometric electrochemical biosensor was proposed to determine human immunodeficiency virus-associated DNA fragment (HIV-DNA) with high sensitivity and selectivity. The dynamic DNA nanosystem was composed of a target recycling unit and a multipedal DNA walker unit. Both of them could be driven by a toehold-mediated strand displacement reaction, enabling an enzyme-free and isothermal amplification strategy for nucleic acid determination. The target recycling unit could selectively recognize HIV-DNA and activate the multipedal DNA walker unit to roll on the electrode surface, which would lead to bidirectional signal variation for ratiometric readout with cascade signal amplification. Benefiting from the synergistic effect of the dynamic DNA nanosystem and the ratiometric output mode, the ultrasensitive detection of HIV-DNA was achieved in a wide linear range of 6 orders of magnitude with a limit of detection of 36.71 aM. The actual usability of the proposed sensor was also verified in complex biological samples with acceptable performance. This dynamic DNA nanosystem-integrated ratiometric sensing strategy might be promising in the development of reliable point-of-care diagnostic devices for highly sensitive and selective pathogen identification.

Arginine-modified black phosphorus quantum dots with dual excited states for enhanced electrochemiluminescence in bioanalysis

The electrochemiluminescence (ECL) is generally emitted via radiative transition of singlet or triplet excited state (S₁ or T₁). Herein, an ECL mechanism with the transitions of both S₁ and T₁ of black phosphorus quantum dots (BPQDs) is found, and an arginine (Arg) modification strategy is proposed to passivate the surface oxidation defects of BPQDs, which could modulate the excited states for enhancing the ECL efficiency of BPQDs. The Arg modification leads to greater spatial overlap of highest and lowest occupied molecular orbitals, and spectral shift of radiative transitions, and improves the stability of anion radical of BPQDs. To verify the application of the proposed mechanism, it is used to construct a sensitive method for conveniently evaluating the inhibiting efficiency of cyclo-arginine-glycine-aspartic acid-d-tyrosine-lysine to cell surface integrin by using Arg containing peptide modified BPQDs as signal tag. The dual excited states mediated ECL emitters provide a paradigm for adjustable ECL generation and extend the application of ECL analysis.

Surface Defect-Involved and Single-Color Electrochemiluminescence of Gold Nanoclusters for Immunoassay

Single-color electrochemiluminescence (ECL) of nanoparticles is normally achieved in a bandgap engineered route via passivating the nanoparticle surface. Herein, when linear mercaptoalkanoic acids are employed as the thiol-capping agent of unary Au nanoclusters (NCs), a single-stabilizer-capped strategy is proposed to achieve surface defect-involved and single-color ECL from the AuNCs with hydrazine (N2H4) as the coreactant. The carbon skeleton of the linear mercaptoalkanoic acids exhibits important effects on the ECL of the AuNCs, and efficient oxidative-reductive ECL is achieved with 8-mercaptooctanoic acid (MOA), 11-mercaptoundecanoic acid (MUA), and 12-mercaptododecanoic acid (MDA) capped AuNCs, respectively. The ECL of these AuNCs not only exhibits similar ECL intensity-potential profiles with the same maximum emission potential of ∼1.20 V (vs Ag/AgCl), but also demonstrates almost identical spectral ECL profiles of the same maximum emission wavelength around 713 nm as well as the same fwhm of 64 nm. The ECL of AuNCs/N2H4 is obviously red-shifted to the photoluminescence of AuNCs, which not only provides unambiguous evidence that bandgap-engineered ECL of these AuNCs is quenched but also manifests that the capping agent of linear mercaptoalkanoic acid is promising for the achievement of surface defect-involved and single-color ECL from AuNCs. The MUA capped AuNCs can be utilized as an ECL tag for a sensitive and selective immunoassay, which exhibits a broad linear range from 0.5 mU/mL to 1 U/mL with a low limit of detection of 0.1 mU/mL (S/N = 3) with CA125 as the model analyte. This work provides a promising alternative to the traditional surface-passivating strategy for the achievement of single-color ECL from nanoparticle luminophores.

Coreactant-free and Near-Infrared Electrochemiluminescence Immunoassay with n-Type Au Nanocrystals as Luminophores

The electrochemiluminescence (ECL) bioassay is prominently carried out with the involvement of the coreactant. To remove the detrimental effects of the coreactant on the ECL of luminophores, herein, a promising ECL immunoassay strategy with biocompatible nanoparticles as the luminophore is proposed, which involves directly and electrochemically oxidizing the luminophore methionine-capped Au (Met@Au) nanocrystals (NCs) without the participation of any coreactant. Met@Au NCs are a kind of n-type nanoparticles, and they can be electrochemically injected with valence band (VB) holes around +0.80 and +1.10 V (vs Ag/AgCl). The electrochemically injected exogenous VB hole can recombine with the endogenous conduction band electron of Met@Au NCs and eventually bring out two coreactant-free and near-infrared ECL processes around 0.80 V (ECL-1) and 1.10 V (ECL-2). The intensity of coreactant-free ECL is primarily determined by the electrochemical oxidation-induced hole-injection process. ECL-2 is considerably stronger than ECL-1 and can be exploited for determining the carcinoembryonic antigen (CEA) in a sandwich immunoassay procedure with a linear range from 0.1 to 50 pg/mL as well as a limit of detection of 0.03 pg/mL (S/N = 3).

Low-Triggering-Potential Single-Color Electrochemiluminescence from Bovine Serum Albumin-Stabilized Unary Au Nanocrystals for Immunoassays

Herein, low-triggering-potential (LTP) electrochemiluminescence (ECL) with an onset around 0.0 V (vs Ag/AgCl) is proposed with bovine serum albumin (BSA)-stabilized Au nanocrystals (BSA-AuNCs) as a luminophore and hydrazine hydrate (N₂H₄) as a coreactant. The BSA-AuNCs/N₂H₄ system can exhibit efficient LTP-ECL around 0.37 V with the luminophore of both monodispersed and surface-confined states. The LTP-ECL of BSA-AuNCs/N₂H₄ is a kind of single-color emission with a maximum emission wavelength around 740 nm, which is obviously red-shifted for 80 nm from that of BSA-AuNCs PL, and indicates that the ECL is generated in a surface-defect-involved route instead of the band-gap-engineered route. Importantly, BSA-AuNCs can be utilized as ECL tags to perform sandwich-type immunoassays with acceptable sensitivity and selectivity, which exhibits a wide linear response for determining CA125 from 0.5 to 1000 mU/mL and a limit of detection of 0.05 mU/mL (S/N = 3).

A General Route for Chemiluminescence of n-Type Au Nanocrystals

The photoluminescence, electroluminescence, and electrochemiluminescence from nanocrystals (NCs) have been extensively exploited for both fundamental and applied investigation over two decades, while the understanding of chemiluminescence (CL) from NCs is still far from clear by now. Herein, a general route for triggering CL from NC luminophore is proposed by extensively exploiting the charge transfer between n-type NCs and oxidants. Oxidants, such as K₂S₂O₈, H₂O₂, KMnO₄, and NaClO, can chemically inject the hole onto the valence band (VB) of methionine-capped n-type AuNCs (Met@AuNCs) and enable the occurrence of efficient radiative-charge-recombination between the chemically injected exogenous VB hole and the pre-existed endogenous conduction band (CB) electron, which eventually results in single-color and defect-involved CL with the maximum emission wavelength around 824 nm. The CL of Met@AuNCs/oxidant is qualified for ultrasensitive CL immunoassay in a similar procedure to the biotin-avidin and magnetic separation involved commercial CL immunoassay and exhibits acceptable performance for linearly determining carcinoembryonic antigen from 50 pg/mL to 100 ng/mL with a limit of detection of 10 pg/mL (S/N = 3). This strategy provides a general route to develop nanoparticulate CL luminophores and might eventually enable CL multiplexing assay via extensively exploiting the CL of different wavebands.

POS0259 A RANDOMIZED CLINICAL TRIAL OF 2-WEEK METHOTREXATE DISCONTINUATION IN RHEUMATOID ARTHRITIS PATIENTS VACCINATED WITH INACTIVATED SARS-COV-2 VACCINE

Background

Patients with rheumatoid arthritis (RA) on methotrexate have reduced vaccine responses. Temporary discontinuation has improved immunogenicity of anti-influenza vaccine, but this strategy has not been evaluated in anti-SARS-CoV-2 vaccines.

Objectives

To evaluate the effect on immunogenicity and safety of 2-week methotrexate (MTX) discontinuation after each dose of the Sinovac-CoronaVac vaccine versus MTX maintenance in rheumatoid arthritis (RA) patients.

Methods

This was a single-center, prospective, randomized, investigator-blinded, intervention study (#NCT04754698, CoronavRheum), including adult RA patients (stable CDAI≤10, prednisone ≤7.5mg/day), randomized (1:1) to withdraw MTX (MTX-hold) for 2 weeks after each vaccine dose or maintain MTX (MTX-maintain), evaluated at D0, D28 and D69. Co-primary outcomes were anti-SARS-CoV-2 S1/S2 IgG seroconversion(SC) and neutralizing antibody (NAb) positivity at D69. Secondary outcomes were geometric mean titers (GMT) and flare rates. For immunogenicity analyses, we excluded patients with baseline positive IgG/NAb, and, for safety reasons, those who flared at D28 (CDAI>10) and did not withdraw MTX twice.

Results

Randomization included 138 patients with 9 exclusions (5 COVID-19, 4 protocol violations). Safety evaluation included 60 (MTX-hold) and 69 (MTX-maintain) patients. Further exclusions: 27 patients [13 (21.7%) vs. 14 (20.3%), p=0.848] with positive baseline IgG/NAb and 10 patients (21.3%) in MTX-hold with CDAI>10 at D28. At D69, MTX-hold (n=37) had a higher rate of seroconversion than MTX-maintain (n=55) group [29 (78.4%) vs 30 (54.5%), p=0.019], with parallel augmentation in GMT [34.2 (25.2-46.4) vs 16.8 (11.9-23.6), p=0.006]. No differences were observed for NAb positivity [23 (62.2%) vs 27 (49.1%), p=0.217]. At D28 flare, rates were comparable in both groups (CDAI, p=0.122; DAS28-CRP, p=0.576), whereas CDAI>10 was more frequent in MTX-hold at D69 (p=0.024).

Figure 1.

Conclusion

We provide novel data that 2-week MTX withdrawal after each Sinovac-CoronaVac vaccine dose improves anti-SARS-CoV-2 IgG response. The increased flare rates after second MTX withdrawal may be attributed to the short-term interval between vaccine doses. This strategy requires close surveillance and shared decision making due to the possibility of flares.

References

[1]​​Jara A, Undurraga EA, González C, et al. Effectiveness of an inactivated SARS-CoV-2 vaccine in Chile. N Eng J Med. 2021 Sep 2;385(10):875-84. doi: 10.1056/NEJMoa2107715

[2]Furer V, Eviatar T, Zisman D, et al. Lb0003 Immunogenicity and Safety of the BNT162B2 mRNA Covid-19 Vaccine in Adult Patients with Autoimmune Inflammatory Rheumatic Diseases and General Population: a Multicenter Study. Ann Rheum Dis. 2021;80:200-201. doi: 10.1136/annrheumdis-2021-220647

[3]Medeiros-Ribeiro AC, Aikawa NE, Saad CG, et al. Immunogenicity and safety of the CoronaVac inactivated vaccine in patients with autoimmune rheumatic diseases: a phase 4 trial. Nat. Med. 2021 Jul 30:1-8. doi: 10.1038/s41591-021-01469-5.

[4]Park JK, Lee MA, Lee EY, et al. Effect of methotrexate discontinuation on efficacy of seasonal influenza vaccination in patients with rheumatoid arthritis: a randomised clinical trial. Ann Rheum Dis. 2017 Sep 1;76(9):1559-65. http://dx.doi.org/10.1136/annrheumdis-2017-211128

[5]Park JK, Lee YJ, Shin K, et al. Impact of temporary methotrexate discontinuation for 2 weeks on immunogenicity of seasonal influenza vaccination in patients with rheumatoid arthritis: a randomised clinical trial. Ann Rheum Dis. 2018 Jun 1;77(6):898-904. http://dx.doi.org/10.1136/annrheumdis-2018-213222

Acknowledgements

This protocol is part of a larger study of immunosuppressed patients with ARD (Clinicaltrials.gov#NCT04754698)

Disclosure of Interests

None declared

Glow and Flash Adjustable Chemiluminescence with Tunable Waveband from the Same CuInS2@ZnS Nanocrystal Luminophore

All commercial chemiluminescence (CL) assays are conducted with either glow or flash CL of eye-visible waveband from chemical luminophores. Herein, glow and flash, as well as waveband adjustable CL from the same nanoparticle luminophore of thiol-capped CuInS₂@ZnS nanocrystals (CIS@ZnS-Thiol), are proposed via extensively exploiting the differed redox nature of CL triggering reagents. Taking thiosalicylic acid (TSA) as the model thiol-capping agent, the electron-injection-initiated charge transfer between CIS@ZnS-TSA and reductant can bring out efficient glow CL while the hole-injection-initiated charge transfer between CIS@ZnS-TSA and oxidant can give off obvious flash CL under optimum conditions. The maximum emission wavelength for CL of CIS@ZnS-TSA is adjustable from 730 nm to 823 nm via employing different triggering agents. Promisingly, the coexistent reductant of N₂H₄·H₂O and oxidant of H₂O₂ can be employed as dual triggering reagents to trigger eye-visible and highly efficient flash CL from CIS@ZnS-TSA. The maximum emission intensity for flash CL of CIS@ZnS-TSA/N₂H₄-H₂O₂ is 101-fold greater than the glow CL of CIS@ZnS-TSA/N₂H₄ and 22-fold greater than the flash CL of CIS@ZnS-TSA/H₂O₂, respectively. The flash CL from CIS@ZnS-TSA/N₂H₄-H₂O₂ is qualified for highly sensitive and selective CL immunoassay in a commercialized typical procedure with the entire operating process manually terminated within 35 min.

Selectively Lighting Up Singlet Oxygen via Aggregation-Induced Electrochemiluminescence Energy Transfer

Singlet oxygen (¹O₂) is an important reactive oxygen species (ROS) that is intensively involved in natural photochemical and photobiological processes. Herein, selectively lighting up ¹O₂ is achieved in the aggregation-induced emission (AIE) of electrochemiluminescence (ECL) from the Zn²⁺-mediated AIE assembly of Au nanoclusters (Zn²⁺-AIE-AuNCs). Zn²⁺-AIE-AuNCs can exhibit efficient AIE ECL and photoluminescence (PL) along with ¹O₂ generation in energy and charge transfer routes, respectively. The AIE ECL of the Zn²⁺-AIE-AuNCs/tripropylamine (TEA) system in carbonate buffer is located around 703 nm with the dimeric aggregate of ¹O₂ as an emitter because electrochemically oxidizing coexisted Zn²⁺-AIE-AuNCs and TEA in carbonate buffer would promote the oxygen vacancy (O_v) of Zn²⁺-AIE-AuNCs, which could selectively enable the generation of emissive singlet oxygen in the energy transfer route by effectively transferring the energy from excited singlet Zn²⁺-AIE-AuNCs to the triplet ground state of dissolved oxygen (³O₂). No emissive ¹O₂ is detected via electrochemically oxidizing the Zn²⁺-AIE-AuNCs in the case without either carbonate buffer or TEA, and the Zn²⁺-AIE-AuNCs/TEA system can only exhibit AIE ECL around 485 nm with Zn²⁺-AIE-AuNCs as the emitter in carbonate-free buffers. Photoexciting Zn²⁺-AIE-AuNCs merely brings out band-gap-engineered AIE PL around ∼485 nm with Zn²⁺-AIE-AuNCs as the emitter, which manifests that the ¹O₂ generated in the charge transfer route via photoexciting Zn²⁺-AIE-AuNCs is un-emissive. This work not only proposes an effective strategy for AIE with ¹O₂ as an emitter but also opens a promising way to selectively light up ¹O₂.

Wilcoxon-Mann-Whitney odds ratio: A statistical measure for ordinal outcomes such as EDSS

BACKGROUND

In many clinical situations, ordinal scales afford the primary method of semi-quantifying patient outcomes. In the field of multiple sclerosis, the primary ordinal scale is the Expanded Disability Status Scale. Predominant methods of ordinal scale statistical analysis provide a p-value without effect size or rely heavily on the assumption of proportionality of odds, subjecting them to lack of power and error. The Wilcoxon-Manny-Whitney Odds is a statistical method which provides significant information such as p-value, effect size, number needed to treat, confidence intervals, and is largely assumption-free. However, its utility has not been demonstrated in the field of multiple sclerosis.

METHODS

Three clinical studies in the field of multiple sclerosis were selected which utilized ordinal scale outcomes at group or individual levels. Data from these studies was extracted using WebPlotDigitizer, and a custom Wilxocon-Mann-Whitney Odds software was applied to each dataset to re-analyze the main outcomes of the studies.

RESULTS

Re-analysis of the manuscript by Muraro et al., 2017 demonstrated that autologous stem cell transplantation for relapsing remitting multiple sclerosis resulted in a 65% chance of improving from any Expanded Disability Status Scale category, although not significant. Re-analysis of the manuscript by Songthammawat et al., 2019 demonstrated chance of improvement with intravenous methylprednisolone and concurrent plasma exchange was 185% versus 32% in intravenous methylprednisolone with add-on plasma exchange, although not significant. Re-analysis of Kister et al., 2012 demonstrated the chances of mobility or cognition scores generally favored decline at every 5-year increment of study, and although statistically significant, these were smaller effect sizes ranging from an 11% chance of improvement to a 66% chance of decline over a 5-year interval.

DISCUSSION

The Wilcoxon-Mann-Whitney Odds simplifies ordinal data analysis with its robust largely assumption-free nature. In the place of numerous statistical tests, this single test provides effect size estimate, number needed to treat, p-values, and confidence intervals. Importantly, the Wilcoxon-Mann-Whitney Odds effect size calculation is intuitively applicable to both individual and population-levels. Further, the Wilcoxon-Mann-Whitney Odds allows intuitive description of the progression of large cohorts over time, and we were able to clearly convey the odds of mobility and cognitive decline over 30 years in a large multiple sclerosis cohort. Overall, the Wilcoxon-Mann-Whitney Odds is a powerful and robust statistical test with significant promise within the field of multiple sclerosis.

Coreactant-Free and Direct Electrochemiluminescence from Dual-Stabilizer-Capped InP/ZnS Nanocrystals: A New Route Involving n-Type Luminophore

Electrochemiluminescence (ECL) is conventionally generated in either an annihilation or a coreactant route, and the overwhelming majority of ECL research is conducted in the coreactant route via oxidizing or reducing the coexisting coreactant and luminophore. The coreacant-free ECL generated via merely oxidizing the luminophore would break through the ceiling of coreactant ECL via excluding the detrimental effects of exogenous coreactant and dissolved oxygen. Herein, by exploiting the rich-electron nature of n-type nanocrystals (NCs), coreacant-free ECL is achieved via merely oxidizing 3-mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA) capped InP/ZnS NCs, i.e., InP/ZnS_MPA-MSA. The electron-rich InP/ZnS_MPA-MSA can be electrochemically injected with holes via two oxidative processes at around +0.75 and +1.37 V (vs Ag/AgCl), respectively, and the exogenous hole can directly combine the conduction band (CB) electron of InP/ZnS_MPA-MSA, resulting in two coreactant-free ECL processes without employing any exogenous coreactant. The deprotonation process for the carboxyl group of the capping agents can provide a negatively charged surface to InP/ZnS_MPA-MSA and enhance the coreactant-free ECL. The hole-injecting process at +1.37 is much stronger than that at +0.75 V and eventually enables an ∼2000-fold enhanced ECL at +1.37 V than that at +0.75 V. The ECL at +1.37 V can be utilized for coreactant-free ECL immunoassay with prostate-specific antigen (PSA) as analyte, which exhibits an acceptable linear response from 5 pg·mL^-1 to 1 ng·mL^-1 with a limit of detection of 0.3 pg·mL^-1. The coreactant-free ECL route would provide an alternative to both annihilation and coreactant routes, simplify the ECL assay procedure and deepening the ECL mechanism investigations.

Low-Triggering-Potential Electrochemiluminescence from Surface-Confined CuInS2@ZnS Nanocrystals and their Biosensing Applications

Electrochemiluminescence (ECL) of low triggering potential is strongly anticipated for ECL assays with less inherent electrochemical interference and improved long-term stability of the working electrode. Herein, effects of the thiol capping agents and the states of luminophores, i.e., the thiol-capped CuInS₂@ZnS nanocrystals (CuInS₂@ZnS-Thiol), on the ECL triggering potential of CuInS₂@ZnS-Thiol/N₂H₄·H₂O were explored on the Au working electrode. The thiol capping agent of glutathione (GSH) not only enabled CuInS₂@ZnS-Thiol/N₂H₄·H₂O with the stronger oxidative-reduction ECL than other thiol capping agents but also demonstrated the largest shift for the ECL triggering potential of CuInS₂@ZnS-Thiol/N₂H₄·H₂O upon changing the luminophores from the monodispersed state to the surface-confined state. CuInS₂@ZnS-GSH/N₂H₄·H₂O exhibited an efficient oxidative-reduction ECL around 0.78 V (vs Ag/AgCl) with CuInS₂@ZnS-GSH of the monodispersed state. Upon employing CuInS₂@ZnS-GSH as the ECL tag and immobilizing them onto the Au working electrode, the oxidative-reduction ECL of CuInS₂@ZnS-GSH/N₂H₄·H₂O was lowered to 0.32 V (vs Ag/AgCl), which was about 0.88 V lower than that of traditional Ru(bpy)₃²⁺/TPrA (typically ∼1.2 V, vs Ag/AgCl). The ECL of the CuInS₂@ZnS-GSH/N₂H₄·H₂O system with the luminophore of both monodispersed and surface-confined states was spectrally identical to each other, indicating that this surface-confining strategy exhibited negligible effect on the excited state for the ECL of CuInS₂@ZnS-GSH. A surface-confined ECL sensor around 0.32 V was fabricated with CuInS₂@ZnS-GSH as a luminophore, which could sensitively and selectively determine the K-RAS gene from 1 to 500 pM with a limit of detection at 0.5 pmol L^-1 (S/N = 3).

Hydrazine Hydrate and Dissolved Oxygen-Triggered Near-Infrared Chemiluminescence from CuInS2@ZnS Nanocrystals for Bioassays

The overwhelming majority of commercially available chemiluminescence (CL) assays are conducted in the eye-visible region. Herein, a near-infrared (NIR) aqueous CL strategy was proposed with CuInS₂@ZnS nanocrystals (CIS@ZnS NCs) as emitters. Hydrazine hydrate (N₂H₄·H₂O) could inject electrons into the conduction band of the CIS@ZnS NCs and simultaneously transformed to the intermediate radical N₂H₃^•. N₂H₃^• reduced dissolved oxygen (O₂) to O₂^-•, while the O₂^-• could inject holes into the valence band of the CIS@ZnS NCs. The recombination of electrons and holes at Cu⁺ defects in CIS@ZnS NCs eventually yielded efficient NIR CL at around 824.1 nm, which is the longest waveband for NCs CL to the best of our knowledge. The NIR CL could be conveniently performed in the neutral aqueous medium (pH 7.0) with a quantum yield of 0.0155 Einstein/mol and was successfully employed for constructing a signal-off CL biosensor with ascorbic acid as the analyte as well as a signal-on CL biosensor for determining ascorbate oxidase, which indicates that this NIR CL system has a promising potential for bioassays in diverse ways.

[Feasibility and safety of fetal intravascular transfusion via the intrahepatic vein in the treatment of fetal anemia]

Objective: To investigate the feasibility and safety of fetal intravascular transfusion via the intrahepatic vein in the treatment of fetal anemia. Methods: This was a retrospective analysis of all fetuses requiring intrauterine transfusion (IUT) in the Shanghai First Maternity and Infant Hospital between January 2010 and December 2019. According to the different ways of IUT, they were divided into intrahepatic venous transfusion group and umbilical venous transfusion group, fetal outcomes and the incidence of procedure-related complications between the two groups were compared. Results: A total of 97 IUTs were performed on 48 fetuses. Among them, 16 cases were performed in the intrahepatic vein (31 transfusions), 32 cases were performed in the cord of the umbilical vein (66 transfusions).There were no significant differences between the two groups in age, labor history and the proportion of fetal hydrops before the first transfusion. In the intrahepatic venous transfusion group, the posterior placenta was 14/16, which was significantly higher than 78% (25/32) in the umbilical venous transfusion group (P<0.01). The live-birth rates of the two groups were 13/16 and 75% (24/32). There was no significant difference between the two groups (P>0.05). Before intrahepatic venous transfusion, the proportion of fetal hydrops was significantly higher than that of umbilical venous transfusion [55% (17/31) vs 24% (16/66), P<0.05]. Puncture success rate of intrahepatic venous transfusion and umbilical venous transfusion were both 100%. In the umbilical venous transfasion group, the incidence of needle slippage (5%, 3/66) and the abnormality of fetal heart rate (11%, 7/66) were higher than those in the intrahepatic venous transfasion group [0 and 3% (1/31)], but there were no significant differences between the two groups (all P>0.05). There were no cases of fetal loss within 24 hours, premature rupture of membranes, infection within 7 days and emergency cesarean section after IUT in both groups. Conclusions: Fetal intravascular transfusion via the intrahepatic vein is safe and feasible in the treatment of fetal anemia. But the requirements of puncture technique are relatively high, so it is recommended to be carried out in experienced fetal treatment center.

Protein-protein interaction network and potential drug target candidates of Streptococcus suis

AIMS

This study aimed to explore potential drug targets of Streptococcus suis at the system level.

METHODS AND RESULTS

A homologous protein mapping method was used in the construction of a protein-protein interaction (PPI) network of S. suis, which presented 1147 non-redundant interaction pairs among 286 proteins. The parameters of PPI networks were calculated and showed scale-free network properties. In all, 41 possibly essential proteins identified from 47 highly connected proteins were selected as potential drug target candidates. Of these proteins, 30 were already regarded as drug targets in other bacterial species. Six transporters with high connections to other functional proteins were identified as probably not essential but important functional proteins. Afterward, the subnetwork centred with cell division protein FtsZ was used in confirming the PPI network through bacterial two-hybrid analysis.

CONCLUSIONS

The predicted PPI network covers 13·04% of the proteome in S. suis. The selected 41 potential drug target candidates are conserved between S. suis and several model bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

The predictions included proteins known to be drug targets, and a verifying experiment confirmed the reliability of predicted interactions. This work is the first to present systematic computational PPI data for S. suis and provides potential drug targets, which are valuable in exploring novel anti-streptococcus drugs.

Use of Triangular Silver Nanoplates as Low Potential Redox Mediators for Electrochemical Sensing

Redox mediators can facilitate the electrochemical communication between targets and electrodes for material characterization and investigation. To provide an alternative to the chemical-based redox mediators, herein, we present a nanoparticle-based redox mediator, i.e., the trisodium citrates (TSC)-capped triangular silver nanoplates (Tri-Ag-NP_TSC), which demonstrates an efficient oxidative process at around 0.13 V (vs Ag/AgCl) with acceptable redox reversibility by exploiting the interaction between the carbonyl group of TSC and the Ag element of Tri-Ag-NP_TSC. The TSC of Tri-Ag-NPs can be selectively replaced by thiols and enable the obtained Tri-Ag-NP_TSC-thiol with changed electrochemical redox response, which could be utilized to determine various thiols at 0.13 V, a much lowered oxidative potential than traditional redox mediators, with a similar linear response range, response slope, and limit of detection (LOD). This work proposes a surface-engineering approach to design and develop electrochemical redox probes using Ag nanoparticles with particular morphology, indicating that the interaction between the carbonyl group and Ag nanoparticles might be extended to sensing application beyond the surface-enhanced Raman scattering.

Electrochemiluminescence ultrasensitive immunoassay for carbohydrate antigen 125 based on AgInS2/ZnS nanocrystals

We developed a near-infrared (NIR) electrochemiluminescence (ECL) immunosensor for sensitively and selectively determining carbohydrate antigen 125 (CA125) with toxic-element-free and environmental-friendly AgInS₂/ZnS nanocrystals (NCs) as tags. The core/shell-structured AgInS₂/ZnS NCs not only can be conveniently prepared via an aqueous synthetic procedure, but also has high photoluminescence quantum yield (PLQY) of up to 61.7%, highly monodispersed, water-soluble, and desired biological compatibility. As AgInS₂/ZnS NCs can be oxidized via electrochemically injecting holes into their valence band at + 0.84 V, both the monodispersed AgInS₂/ZnS NCs in solution and the surface-confined AgInS₂/ZnS NCs immobilized in sandwich-typed immuno-complexes with CA125 as analyte can exhibit efficient oxidative-reduction ECL around 695 nm under physiological conditions with the presence of tri-n-propylamine (TPrA). The ECL intensity from the AgInS₂/ZnS NCs immobilized in sandwich-typed immuno-complexes increases linearly and selectively with an increased concentration of CA125 from 5 × 10^-6 to 5 × 10^-3 U/mL, and limit of detection (LOD) was 1 × 10^-6 U/mL (S/N = 3). This reliable platform can provide an effective detection method in the early diagnosis and treatment of ovarian cancer.

Enhanced Near-Infrared Electrochemiluminescence from Trinary Ag-In-S to Multinary Ag-Ga-In-S Nanocrystals via Doping-in-Growth and Its Immunosensing Applications

Screening toxic-element-free and biocompatible electrochemiluminophores was crucial for electrochemiluminescence (ECL) evolution. Herein, l-glutathione (GSH)-capped Ag-Ga-In-S (AGIS) nanocrystals (NCs) were prepared by doping Ag-In-S (AIS) NCs in a doping-in-growth way and utilized as a model for both ECL modulating and developing multinary NC-based electrochemiluminophores with enhanced ECL performance than trinary NCs. AGIS NCs not only primarily preserved the morphology, size, phase structure, and water monodisperse characteristics of AIS NCs with broadened band gap but also demonstrated obviously enhanced oxidative-reduction ECL than AIS NCs. Importantly, ECL of AGIS NCs was located at the near-infrared region with a maximum emission wavelength of 744 nm and could be utilized for an ECL immunoassay with human prostate-specific antigen (PSA) as a model, which exhibited a linearity range from 0.05 pg/mL to 1.0 ng/mL and a low limit of detection of 0.01 pg/mL (S/N = 3). This work provided a promising alternative to the traditional binary NCs for developing toxic-element-free and biocompatible electrochemiluminophores with efficient near-infrared ECL.

Influence of lymph node dissection in patients undergoing radical nephrectomy for non-metastatic renal cell carcinoma: a systematic review and meta-analysis

OBJECTIVE

Whether lymph node dissection (LND) should be performed concomitantly with radical nephrectomy (RN) for non-metastatic renal carcinoma has still been controversial recently. We conducted a meta-analysis assessing oncologic outcomes of radical nephrectomy with lymph node dissection (LND) and without lymph node dissection (non-LND) in non-metastatic renal cell carcinoma (NMRCC).

PATIENTS AND METHODS

A systematic review was performed until April 2018 using a comprehensive search in PubMed, EMBASE, and Cochrane Library databases to identify eligible comparative studies. A formal meta-analysis was performed for studies comparing radical nephrectomy with LND and radical nephrectomy with non-LND for cT1-T4NxM0 tumors. Furthermore, a subgroup analysis for locally advanced renal cell carcinoma (cT3-T4NxM0) was conducted.

RESULTS

Thirteen studies on patients with LND and non- LND were identified and included in the analysis. LND group did not have a significantly better survival than non-LND group for cT1-T4NxM0 tumors (HR 0.93, 95% CI 0.78-1.11, p=0.45), However, in the subgroup of locally advanced renal cell carcinoma (cT3-T4NxM0), it showed a significantly better OS rate in patients who had undergone LND compared to those without LND (HR 0.73, 95% CI 0.60-0.90; p=0.003).

CONCLUSIONS

LND offers better cancer control and better long-term survival in locally advanced renal cell carcinomas (cT3-T4NxM0). This conclusion should be confirmed by a prospective randomized clinical trial.

MiR-216a-5p act as a tumor suppressor, regulating the cell proliferation and metastasis by targeting PAK2 in breast cancer

OBJECTIVE

Our study aimed to investigate the expression of microRNA-216a-5p (miR-216a-5p) in breast cancer (BC) and its effect on the proliferation and metastasis of BC cells by regulating the expression of p21-activated protein kinase 2 (PAK2) gene.

PATIENTS AND METHODS

A total of 50 cases of cancer tissue specimens and corresponding para-carcinoma normal tissue specimens were collected from the breast surgery department of our hospital from July 2016 to December 2017. BC MCF-7 cell line and normal breast epithelial MCF-10A cells were cultured. MiR-NC (negative control), LV-p21-activated protein kinase 2 (PAK2) and/or miR-216a-5p mimics were synthesized and transfected. The protein and mRNA expression level in BC tissues and cells were detected by Western blot and quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) assay, respectively. Additionally, the Luciferase Reporter Assays, cell proliferation detection, clone formation assays and transwell migration and invasion assay were performed to determine the functional alteration of BC cells, respectively.

RESULTS

The results of qRT-PCR demonstrated that miR-216a-5p was decreased in both BC tissues and cells compared with that in normal controls. Online target gene prediction software and Dual-Luciferase reporter assay were used for target identification, and PAK2 was identified as a functional target of miR-216a-5p in BC cells. The results were further clarified with the Western blot (WB) experiment. In vitro, cell functions were detected by Cell Counting Kit-8 (CCK-8), crystal violet staining and transwell experiment, respectively. The results indicated that decreased expression of PAK2 resulting from the up-regulation of miR-216a-5p could restrain the proliferation, clone formation, invasion and migration abilities of BC cells.

CONCLUSIONS

We showed that miR-216a-5p played a role as antioncogene in BC, which provides a new therapeutic target for the treatment of BC.

Electrochemically Lighting Up Luminophores at Similar Low Triggering Potentials with Mechanistic Insights

Electrochemiluminescence (ECL) with high electrode compatibility and less electrochemical interference has conventionally been envisioned by lowering the oxidative potential of luminophores and/or screening luminophores with a low oxidative potential. Herein, an alternative was developed by employing the environmental-friendly carbohydrazide as a coreactant, which enabled serial luminophores with oxidative-reduction ECL at one similar low triggering potential around 0.55 V versus Ag/AgCl, including Ru(bpy)₃²⁺ as well as CdTe, CdSe, CuInS₂/ZnS, and Au nanocrystals. Because the eight-electron releasing process of carbohydrazide was electrochemically triggered at ∼0.25 V versus Ag/AgCl, the radicals generated via electrochemical oxidation of carbohydrazide could reduce the luminophores at a much lower potential than those of traditional coreactants. All the luminophore/carbohydrazide systems exhibited one ECL process around 0.55 V, which was about 0.65 V lower than that of a traditional Ru(bpy)₃²⁺/tri-n-propylamine system (typically around +1.2 V), and even lower than the oxidative potential of some luminophores. The ECL of the luminophore/carbohydrazide system was spectrally close to that of the corresponding luminophore/tri-n-propylamine system; the maximum emission wavelength of the low triggering potential ECL could shift from 540 to 783 nm via the selection of luminophores in this case. The coreactant screening strategy would be a favorable addition to the expected luminophore screening strategy for achieving enhanced ECL performance. This work created an avenue toward a deeper understanding of the ECL mechanism.

Tunable electrochemiluminescence properties of CsPbBr3perovskite nanocrystals using mixed-monovalent cations

Herein, we demonstrate a simple approach for tuning the elecrochemiluminescence (ECL) properties of CsPbBr₃perovskite nanocrystals by using mixed-monovalent cations.

Mechanistic investigations into synergistically enhanced radiative-charge-transfer in Au–Ag bimetallic nanoclusters

Synergetic effects in Au–Ag bimetallic nanoclusters more favorably enhanced electrochemical redox induced electrochemiluminescence over photoexcitation induced photoluminescence.

Correction: Mechanistic investigations into synergistically enhanced radiative-charge-transfer in Au–Ag bimetallic nanoclusters

Correction for 'Mechanistic investigations into synergistically enhanced radiative-charge-transfer in Au–Ag bimetallic nanoclusters' by Jianbo Liu et al., Chem. Commun., 2020, 56, 5665–5668, DOI: 10.1039/D0CC02047H.

Promising Mercaptobenzoic Acid-Bridged Charge Transfer for Electrochemiluminescence from CuInS2@ZnS Nanocrystals via Internal Cu+/Cu2+ Couple Cycling

Screening novel electrochemiluminescence (ECL) systems with less inherent interference is strongly anticipated for ECL evolution. Herein, near-infrared ECL (∼730 nm) with an ultralow triggering potential of 0.45 V (vs Ag/AgCl) is achieved under physiological conditions with 4-mercaptobenzoic acid (MBA) and citrate capped CuInS₂@ZnS (CIS@ZnS) nanocrystals (NCs), which is promising for less autofluorescence and electrochemical interference. Cu⁺ species within the CIS@ZnS NCs can be electrochemically oxidized at 0.45 V to form internal Cu²⁺ defects, while the capping agent MBA can bridge a direct charge transfer between the oxidized NCs and the traditional coreactant tripropylamine (TPrA) for weak ECL at 0.45 V. When hydrazine hydrate is adopted as coreactant, CIS@ZnS NCs/hydrazine hydrate exhibits 8k-fold enhanced oxidative-reduction ECL via the internal Cu⁺/Cu²⁺ couple cycling at 0.45 V in comparison to CIS@ZnS NCs/TPrA. This work opens a way to enhance the radiative charge transfer of NCs.