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Graphdiyne oxide quantum dots (GDYO QDs), as derivatives of graphdiyne (GDY), have excellent electroconductibility and luminous properties and can be applied as a new ECL emitter. Herein, an electrochemiluminescence (ECL) biosensor for miRNA-21 ultrasensitive determination is constructed based on AuNPs/GDY, GDYO QD and oligonucleotide signal amplification strategy that integrates DNA walker and hybridization chain reaction (HCR) amplification. As electrode substrate material, AuNPs/GDY can not only bond with the aptamer CP but can also enhance the conductivity of the interface. When miRNA-21 exists, the DNA walker process is initiated, and the signaling probes are introduced on the electrode surface, producing abundant double-stranded H1/H2; then, H3/H4 undergoes complementary base pairing with H1/H2 through HCR. With the increase in miRNA-21, the 3D DNA nanomachine is actively manipulated, resulting in a gradual increase in ECL signal. This ECL biosensor demonstrates outstanding performance in the determination of miRNA-21 in the linear range from 0.1 fM to 1 nM. This study offers a new sensitive idea for the clinical analysis of cancer biomarkers. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) is an sp and sp2 co-hydrocarbon allotrope whose particular structure endows it with many fascinating properties, including abundant chemical bonds, high conjugation, natural pores, high carrier mobility, high conductivity and stability, etc. In this work, two-dimensional graphdiyne is prepared as an electrode substrate material coupling with an exonuclease III-assisted amplification strategy to construct a superior-performance self-powered biosensor based on enzymatic biofuel cells for highly sensitive detection of the tumour marker miRNA-21. Glucose oxidase (GOD) is first immobilized on the GDY/AuNP composite to prepare a bioconjugate. GDY/AuNP modified carbon cloth is used as an enzyme biofuel cell electrode, which is then modified with bilirubin oxidase as a biocathode. The bioconjugate binds to GOD through specific binding to the bioanode. When miRNA-21 is present, specific recognition by exonuclease III in the system results in cleavage of the capture probe, and miRNA-21 is recovered and involved in the cycle. The target miRNA-21 then causes corresponding changes in the open-circuit voltage of the self-powered system. Based on this, a sensitive detection method was constructed, within the scope from 0.1 fM to 0.1 nM with a shallow detection limit of 55.2 aM (S/N = 3). The new approach triumphantly has been used to detect miRNA-21 in serum, which provides a compelling new way for early diagnosis of related cancers. [ABSTRACT FROM AUTHOR]

Background: MicroRNA (miRNA) plays vital roles in the regulation of both plant architecture and stress resistance through cleavage or translation inhibition of the target messenger RNAs (mRNAs). However, miRNA-induced gene silencing remains a major challenge in vivo due to the low delivery efficiency and instability of miRNA, thus an efficient and simple method is urgently needed for miRNA transformation. Previous researches have constructed a star polycation (SPc)-mediated transdermal double-stranded RNA (dsRNA) delivery system, achieving efficient dsRNA delivery and gene silencing in insect pests. Results: Here, we tested SPc-based platform for direct delivery of double-stranded precursor miRNA (ds-MIRNA) into protoplasts and plants. The results showed that SPc could assemble with ds-MIRNA through electrostatic interaction to form nano-sized ds-MIRNA/SPc complex. The complex could penetrate the root cortex and be systematically transported through the vascular tissue in seedlings of Arabidopsis and maize. Meanwhile, the complex could up-regulate the expression of endocytosis-related genes in both protoplasts and plants to promote the cellular uptake. Furthermore, the SPc-delivered ds-MIRNA could efficiently increase mature miRNA amount to suppress the target gene expression, and the similar phenotypes of Arabidopsis and maize were observed compared to the transgenic plants overexpressing miRNA. Conclusion: To our knowledge, we report the first construction and application of star polycation nanocarrier-based platform for miRNA delivery in plants, which explores a new enable approach of plant biotechnology with efficient transformation for agricultural application. [ABSTRACT FROM AUTHOR]

An increasing number of biosensor design strategies have emerged in recent years, capable of providing potential practical applications for point-of-care testing (POCT) in various human diseases. Compared to conventional biosensors, the latest POCT assays research aims at improving sensor precision, cost-effectiveness and time-consumption. Here，an electrochemiluminescence biosensor and colorimetric method is emerged for rapid, accurate and sensitive determination of biomarker microRNA-141. The target firstly opens the hairpins formed by Ag(I) that acting as a bridge between two cytosine, and the released Ag(I) is selectively recognized by CdTe quantum dots resulting in a decrease in electrochemiluminescence signal and a color change in solution as a visual signal. Then, the introduction of assistant DNA triggers a subsequent catalytic hairpin assembly reaction (CHA), allowing the target to be continuously cycled and further scaled up. The emerging sensor has the advantages of simple, fast (the whole detection process takes about 4 h，takes less time than other biosensors), high sensitivity, good selectivity, and wide linear range (100 aM to 100 pM, with a low LOD as 41.6 aM for electrochemiluminescence and 123.8 aM for colorimetric, respectively), eliminating probe labeling and analysis strategies, which greatly improves the practicality of the method and is expected to realize low-cost and high-sensitivity POCT of microRNAs. • An HO-ECL/colorimetric dual-readout biosensor is developed for microRNA based on CRR cascade CHA. • Dual signal readout and POCT applications are achieved based on only one luminescent emitter. • The proposed biosensor shows a high reliability and sensitivity with a faster, cheaper, and better detection method. [ABSTRACT FROM AUTHOR]