PEG-functionalized black phosphorus quantum dots as stable and biocompatible electrochemiluminescence luminophores for sensitive detection of tumor biomarker.

Despite black phosphorous (BP) QDs possess the merits of size-tunable band-gap, high electron mobility, and intrinsic defects, the spontaneous agglomeration and rapid oxidation of BP QDs in aqueous solution caused low electrochemiluminescence (ECL) efficiency and unstable ECL signal, which confined its further application of biological analysis. Herein, polyethylene glycol-functionalized BP QDs (PEG@BP QDs) were prepared showing an efficient and stable ECL response, which is attributed to the fact that PEG as protectant not only effectively prevented the spontaneous agglomeration, but also restrained the rapid oxidation of BP QDs in aqueous solution. As proof-of-concept, PEG@BP QDs were used as an efficient ECL emitter to combine with palindrome amplification-induced DNA walker to construct a sensitive ECL aptasensing platform for detecting cancer marker mucin 1 (MUC1). Interestingly, with the aid of positively charged thiolated PEG, the reaction rate of DNA walker on the electrode interface was clearly increased for the recovery of the ECL signal. The ECL aptasensor provides sensitive determination with the detection limit of 16.5 fg/mL. The proposed strategy paves a path for the development of efficient and stable ECL nanomaterials to construct biosensors for biosensing and clinical diagnosis.

Highly Efficient Electrochemiluminescence of MnS:CdS@ZnS Core-Shell Quantum Dots for Ultrasensitive Detection of MicroRNA.

In this work, a novel electrochemiluminescence (ECL) biosensor was developed for ultrasensitive detection of microRNA let-7a (miRNA let-7a) based on MnS:CdS@ZnS core-shell quantum dots (QDs) as ECL luminophores with high ECL efficiency. Impressively, compared to the CdS:Mn@ZnS QDs prepared by ionic doping with ECL efficiency of 0.87%, MnS:CdS@ZnS QDs synthesized by bimetallic clusters (Cd2Mn2O4) doping exhibited high ECL efficiency of up to 15.84% with S2O82- as cathodic coreactant due to the elimination of the dopants size mismatch and "self-purification" effect, which could achieve the surface defect passivation of MnS:CdS@ZnS QDs for effectively improving the ECL emission. Furthermore, with the help of strand displacement amplification (SDA), the trace target miRNA let-7a was able to be converted to a number of output DNA labeled with ferrocene (Fc) to construct an ultrasensitive ECL biosensor. The well-designed ECL biosensor for miRNA let-7a exhibited high stability and excellent sensitivity of a concentration variation from 10 aM to 1 nM and a low detection limit of 4.1 aM, which was further applied to the analysis of miRNA let-7a from cancer cell (MCF-7) lysate. Thus, this strategy provides a novel method to prepare high-efficient ECL emitters for the construction of ECL biosensing platforms in biological fields and clinical diagnosis.

Influence of epicatechin on oxidation-induced physicochemical and digestibility changes in porcine myofibrillar proteins during refrigerated storage.

BACKGROUND: The influence of epicatechin (EC) on the physicochemical properties and digestibility changes of porcine myofibrillar protein (MP) under oxidative stress during refrigerated storage was investigated. RESULTS: The incubation of MP suspensions (20 mg mL-1 in piperazine-N,N'-bis(2-ethanesulfonic acid) buffer, with 0.6 mol L-1 sodium chloride, pH 6.25) at 4 °C for 24 h under an iron-catalyzed hydroxyl radical generating system (Fenton reaction) promoted the formation of thiobarbituric acid reactive substances and protein carbonyls, which was attenuated by EC (5, 50, and 100 µmol g-1 protein). Reduced protein sulfhydryl content, tryptophan fluorescence, protein solubility, as well as increased surface hydrophobicity were found by the co-incubation of EC. Analysis by scanning electron microscopy revealed increased protein aggregation and fragments in oxidized MP, which were further enhanced by the addition of EC. However, the protein digestibility of MP was not affected. CONCLUSION: EC was demonstrated to be effective in alleviating lipid oxidation and protein carbonylation in MP under oxidative stress. Additionally, the physicochemical and digestibility changes accompanying the incorporation of EC was complicated due to the possible phenol-protein interactions. An in-depth understanding of protein physicochemical and digestibility changes will be helpful in the application of polyphenolic compounds as antioxidants in low-temperature-processed muscle foods. © 2020 Society of Chemical Industry.

High-Efficient Electrochemiluminescence of BCNO Quantum Dot-Equipped Boron Active Sites with Unexpected Catalysis for Ultrasensitive Detection of MicroRNA.

Herein, the boron radical active sites of boron carbon oxynitride quantum dots (BCNO QDs) are electrically excited to produce boron radicals (B•) for catalyzing peroxydisulfate (S2O82-) as a coreactant to accelerate the generation of abundant sulfate radicals (SO4•-) for significant enhancement in the electrochemiluminescence (ECL) efficiency of BCNO QDs, which overcome the defect of traditional carbon-based QDs with low ECL efficiency. Impressively, under extremely low concentration of S2O82- solution, the BCNO QDs/S2O82- system could exhibit high ECL emission, realizing environmental friendliness and excellent biocompatibility for sensitive bioanalysis. As a proof-of-concept, BCNO QDs, a new generation of ECL emitters with high ECL efficiency, were successfully used in the ultrasensitive determination of microRNA-21, which pushes the exploration of new ECL emitters and broadens the application in the field of clinical diagnosis, ECL imaging, and molecular devices.

Three-Dimensional Cadmium Telluride Quantum Dots-DNA Nanoreticulation as a Highly Efficient Electrochemiluminescent Emitter for Ultrasensitive Detection of MicroRNA from Cancer Cells.

In this work, a novel three-dimensional cadmium telluride quantum dots-DNA nanoreticulation (3D CdTe QDs-DNA-NR) was used as a signal probe with the dual-legged DNA walker circular amplification as target conversion strategy to establish a pioneering electrochemiluminescence (ECL) biosensing strategy for ultrasensitive detection of microRNA-21 form cancer cells. Herein, such a 3D luminous nanomaterial with reticular structure not only supported abundant CdTe QDs to avoid the inner filter effect for obtaining a high ECL efficiency but also contained the hemin/G-quadruplex as coreaction accelerator in the 3D CdTe QDs-DNA-NR/S2O82- system for the enhancement of ECL intensity. Furthermore, with the target-induced dual-legged DNA walker circular amplification strategy, a mass of output DNA was produced to connect with the 3D CdTe QDs-DNA-NR for the construction of the ECL biosensor, which realized the ultrasensitive detection of microRNA-21 from 100 aM to 100 pM and the detection limit down to 34 aM. Significantly, this work could be readily extended for the detection of other biomolecules to provide a neoteric channel for disease diagnosis.