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In this work, a reusable DNA sensing microchip was developed for detection of vomitoxin (deoxynivalenol, DON) in sorghum using Cd-based core-shell CdSe@CdS quantum dots (QDs) as promising electrochemiluminescence (ECL) emitter. The size-adjustable aqueous phase CdSe@CdS QDs were prepared through homogeneous method, exhibiting strong cathodic ECL emission with a central wavelength of 520 nm in S 2 O 8 2− coreactant. And gold nanoparticles-modified iron cobalt cyanide hydrate (Fe–Co–Au) was introduced as an accelerator to amplify the ECL signal. ECL signal was quenched after the formation of a double-stranded (dsDNA) S1–S2 by generating an electron transfer system between the emitter and ferrocene (Fc), which are modified on the aptamer (ssDNA S1) and its complement sequence (ssDNA S2), respectively. When the target DON is presence, the aptamer ssDNA S1 will bind to the DON and trigger the unbinding of double strands DNA and the release of the ssDNA S2, thus the signal can be generated. This approach offers a feasible method for the detection of DON within the range of 1 ng/mL to 200 ng/mL. [Display omitted] • The detection processes are performed in the reusable microchip. • CdSe@CdS QDs as ECL emitter showed remarkable potential in vomitoxin sensor. • The ECL enhancement mechanism of Fe–Co–Au accelerator was fully discussed. • The hybridization chain reaction was introduced into the sensing system. [ABSTRACT FROM AUTHOR]

Carcinoembryonic antigen (CEA) is a significant glycosylated protein, and the unusual expression of CEA in human serum is used as a tumor marker in the clinical diagnosis of many cancers. Although scientists have reported many ways to detect CEA in recent years, such as electrochemistry, photoelectrochemistry, and fluorescence, their operation is complex and sensitivity is average. Therefore, finding a convenient method to accurately detect CEA is significance for the prevention of malignant tumors. With high sensitivity, quick reaction, and low background, electrochemiluminescence (ECL) has emerged as an essential method for the detection of tumor markers in blood. In this work, a "signal on-off" ECL immunosensor for sensitive analysis of CEA ground on the ternary extinction effects of CuFe 2 O 4 @PDA-MB towards a self-enhanced Ru(dcbpy) 3 2+ functionalized metal-organic layer [(Hf)MOL-Ru-PEI-Pd] was prepared. The high ECL efficiency of (Hf)MOL-Ru-PEI-Pd originated from the dual intramolecular self-catalysis, including intramolecular co-reaction between polyethylenimine (PEI) and Ru(dcbpy) 3 2+. At the same time, loading Pd NPs onto (Hf)MOL-Ru-PEI could not only improve the electron transfer ability of (Hf)MOL-Ru-PEI, but also provide more active sites for the reaction of Ru(dcbpy) 3 2+ and PEI. In the presence of CEA, CuFe 2 O 4 @PDA-MB-Ab 2 efficiently quenches the excited states of (Hf)MOL-Ru-PEI-Pd by PDA, Cu2+, and methylene blue (MB) via energy and electron transfer, leading to an ECL signal decrease. Under optimal conditions, the proposed CEA sensing strategy showed satisfactory properties ranging from 0.1 pg mL−1 to 100 ng mL−1 with a detection limit of 20 fg mL−1. The (Hf)MOL-Ru-PEI-Pd and CuFe 2 O 4 @PDA-MB were prepared in this work might open up innovative directions to synthesize luminescence-functionalized MOLs and effective quencher. Besides, the ECL quenching mechanism of Ru(dcbpy) 3 2+ by MB was successfully explained by the inner filter effect (ECL-IFE). At last, the proposed immunosensor exhibits excellent repeatability, stability, and selectivity, and may provide an attractive way for CEA and other disease markers determination. [Display omitted] • ECL signal originated from intramolecular co-reaction between PEI and Ru(dcbpy) 3 2+. • CuFe 2 O 4 @PDA-MB quenches the excited states of Ru(dcbpy) 3 2+ by PDA, Cu2+, and MB. • ECL signal quenching of Ru(dcbpy) 3 2+ by MB was explained by the inner filter effect. • High-performance ECL immunosensing of CEA. [ABSTRACT FROM AUTHOR]

The improvement of electrochemiluminescence (ECL) performance relies on the electron transfer efficiency between luminophore and coreactant. An ultrasensitive ECL micro-reactor with confinement-enhanced performance was prepared by using the covalent organic framework-LZU1-functionalized metal-organic framework (MOF@COF-LZU1) as a platform to assemble enormous N,N -dibutyl-2-hydroxyethylamine (DBAE) and tris(4,4′-dicarboxylic acid-2,2′-bipyridyl) ruthenium(II) [Ru(dcbpy) 3 2+] into its pore channels. Compared to individual substances of γ-CD-MOF and COF-LZU1, the synergistic effects can conduce to the enhancement of the intensity, durability and sensitivity of the micro-reactor. Besides, COF-LZU1 can provide a mild environment to accommodate a certain amount of DBAE by concentrating them from the aqueous solution into its hydrophobic cavities and boost the oxidation efficiency of DBAE to generate more DBAE●+ and profited the survival of DBAE●, leading to an improved reaction efficiency with the Ru(dcbpy) 3 2+ intermediate. Thanks to the confinement-enhanced strategy, engineered as high-functioning luminescent materials, Ru@γ-CD-MOF@COF-LZU1 micro-reactors decorated with Au NPs can facilitate electron transfer and capture primary antibodies (Ab 1). Moreover, Au–Pd–Pt noble metal aerogels (NMAs) functionalized MoS 2 NFs (Au–Pd–Pt NMAs@MoS 2 NFs) were chosen as base material due to its large specific surface areas, high porosity, and excellent electrical conductivity. Based on above merits, the sensor demonstrated a sensitive response to CYFRA 21-1 detection in a linear concentration gradient from 10 fg/mL to 50 ng/mL with a detection limit of 0.0055 pg/mL (S/N = 3). The COF-LZU1 decorated ECL micro-reactors were constructed based on the signal amplification strategies to realize accurate CYFRA 21-1 detection. [Display omitted] • MOF@COF-LZU1 synergistic effects, the performance of ECL can be improved. • Ru@γ-CD-MOF@COF-LZU1 as high-functioning luminescent materials. • Au–Pd–Pt NMAs@MoS 2 NFs were chosen as base material. • The ECL immunosensor showed wide detection range and low LOD for CYFRA 21-1. [ABSTRACT FROM AUTHOR]

• Mo 2 C employed as nanocarriers of luminol-capped Au nanoparticles. • UCNPs-Pt@MOF used as label and signal amplification mediator. • The ECL immunosensor exhibited a low detection limit of 3.8 fg/mL. A competitive electrochemiluminescence (ECL) immunosensor for sensitive detection of diethylstilbestrol (DES) was successfully fabricated. Initially, molybdenum carbides (Mo 2 C) with excellent conductivity and large surface area were applied as the ECL reagent nanocarriers of luminol-capped Au nanoparticles (luminol-AuNPs). ECL performance of luminol-AuNPs with Mo 2 C (lumino-AuNPs@Mo 2 C) hybrid get enhanced in comparison with individual luminol-AuNPs due to facilitated electron transfer process. To carry out successful fabrication of competitive immunosensor, the label was constructed by encapsulating upconversion nanoparticles (UCNPs) functionalized by platinium into metal-organic frameworks (UCNPs-Pt@MOF). The synthesized UCNPs-Pt@MOF firmly anchored DES-antigen (Ag) by covalent bonding and was able to convert longer wavelength irradiation to shorter wavelength emission. In addition, UCNPs-Pt@MOF has been used as signal amplification mediator and it exhibited high catalytic activity towards hydrogen peroxide. Under optimal experimental condition, reliable and successful determination of DES was done within linear range of 0.1 pg/mL to 30 ng/mL with detection limit of 3.8 fg/mL (S/N = 3). The ECL immunosensor exhibited acceptable selectivity, good sensitivity and high repeatability. Moreover, the proposed competitive ECL immunosensor was evaluated by detecting DES in real water samples with satisfactory results. Therefore, this immunosensor has potential application values for detecting DES and other environmental pollutants. [ABSTRACT FROM AUTHOR]