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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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A novel photoelectrochemical (PEC) immunosensor for the determination of cardiac troponin I (cTnI) was constructed. The flower-like stannic oxide (SnO 2 ) with large specific surface area was prepared by hydrothermal synthesis. Nitrogen-doped carbon quantum dots (NCQDs) with excellent surface property were used as a sensitizer for SnO 2 . Bismuth oxyiodide (BiOI) is a narrow band gap (1.83 eV) nanomaterial, which was firstly modified on NCQDs-sensitized SnO 2 through in situ growth method. After NCQDs with small size and BiOI nanoparticles are successively combined with SnO 2 , the SnO 2 /NCQDs/BiOI microflower was obtained, which possessed good photochemical properties. Using visible light as excitation source and ascorbic acid (AA) as electron donor, the ultrasensitive and quantitative determination of cTnI was realized by detecting the changes of photocurrent under different concentrations of cTnI. The PEC immunosensor showed a large-scaled response (0.001-100 ng mL -1 ) and a low detection limit (0.3 pg mL -1 ) under optimised experimental conditions. The sensor has potential clinical value in the prediction and diagnosis of cardiovascular diseases in elderly patients with diabetes. Graphical abstract.

In this work, the heterostructures of Au nanoparticles loaded on 3D flower-like α-Fe 2 O 3 (Au NPs/α-Fe 2 O 3 ) as a platform and core-shell CdSe@CdS quantum dots sensitized graphene oxide (GO/CdSe@CdS QDs) as a signal amplification label were established in an ultrasensitive sandwich-type photoelectrochemical (PEC) immunosensor based on the "signal-on" type amplification method for detection of amyloid β-protein (Aβ). Specifically, the ultrahigh sensitivity of the proposed immunosensor came from two main properties. First, Au NPs/α-Fe 2 O 3 could partially absorb visible-light, which dramatically promotes electron transfer because of the excellent conductivity of Au NPs, and effectively inhibits the electron-hole recombination, thanks to the effect of heterostructures. Second, the signal-on type is based on the signal amplification label of GO/CdSe@CdS QDs which on adequate absorption of visible-light can improve generation of photogenerated electron-hole pairs effectively. Under optimal conditions, the well-prepared PEC immunosensor exhibited a low detection limit of 0.02 pg mL -1 and a wide linear range from 0.06 pg mL -1 to 350 ng mL -1 for Aβ detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising pathway for detection of other important biomarkers.

As an inflammatory marker, procalcitonin (PCT) is more representative than other traditional inflammatory markers. In this work, a highly efficient photoelectrochemical (PEC) immunosensor was constructed based on the photoactive material Bi2S3/Ag2S to realize the sensitive detection of PCT. Bi2S3 was prepared by a hydrothermal method, and Ag2S quantum dots were deposited on the ITO/Bi2S3 surface via in situ reduction. Bi2S3 is a kind of admirable photoelectric semiconductor nanomaterial on account of its moderate bandgap width and low binding rate of photogenerated electron holes, which can effectively convert light energy into electrical energy. Therefore, based on the energy level matching principle of Bi2S3 and Ag2S, a labeled Bi2S3/Ag2S PEC immunosensor was constructed, and the sensitive detection of PCT was successfully established. The linear detection range of the PEC immunosensor was 0.50 pg∙mL−1 to 50 ng∙mL−1, and the minimum detection limit was 0.18 pg∙mL−1. Compared with the traditional PEC strategy, the proposed PEC immunosensor is simple, convenient, and has good anti-interference, sensitivity, and specificity, which could provide a meaningful theoretical basis and reference value for the clinical detection of PCT. [ABSTRACT FROM AUTHOR]

Using nitrogen-doped carbon quantum dots (NCQDs) and antimony trisulfide (Sb2S3) to co-sensitize hydrangea-shaped tungsten trioxide (WO3), a novel photoelectrochemical (PEC) immunosensor was constructed to sensitively detect procalcitonin (PCT). WO3 possessed a three-dimensional structure with uniform size and large surface area on the indium tin oxide (ITO) electrode. NCQDs with abundant carboxy groups and excitation-independent PEC behavior were modified on the surface of the WO3 coating to enhance photochemical activity. Hence, the hydrangea-shaped WO3/NCQDs/Sb2S3 composite was obtained by modifying NCQDs and well-crystallized Sb2S3 nanoparticles on WO3 through a layer-by-layer assembly. It is worth noting that the photoelectric signal of WO3/NCQDs/Sb2S3 was about 8 times that of pure WO3 under visible light excitation. Moreover, the PEC immunosensor showed a large-scale response (0.001–100 ng mL−1) and a low detection limit (0.42 pg mL−1) under the best experimental conditions. This PEC immunosensor has advantages such as simplicity, facile fabrication, high sensitivity and strong stability, which have good research value in the analysis and detection of disease biomarkers. [ABSTRACT FROM AUTHOR]

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor was developed to detect amyloid β-protein (Aβ) based on CdS/CdTe-cosensitized SnO2 nanoflowers. Specifically, SnO2 with a flower-like porous nanostructure was utilized as a perfect substrate for the construction of PEC immunosensors, and the SnO2-modified electrode was first coated with CdTe quantum dots (QDs) and then further deposited with CdS by successive ionic layer adsorption and reaction techniques. The formed SnO2/CdS/CdTe-cosensitized structure exhibited excellent photocurrent intensity and was employed as an excellent photoactive matrix to immobilize Aβ antibody to further construct the immunosensor. Under optimal conditions, the as-constructed PEC immunosensor was used to detect Aβ and exhibited a wide linear concentration range from 0.5 pg mL−1 to 10 ng mL−1, with a low limit of detection (LOD, 0.18 pg mL−1, S/N = 3). Meanwhile, it also presented good reproducibility, specificity, and stability and may open a new promising platform for the clinical detection of Aβ or other biomarkers. [ABSTRACT FROM AUTHOR]