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Exploring new highly efficient electrochemiluminescence (ECL) luminophores is a necessary condition for developing ultrasensitive ECL biosensors. Therefore, a luminescent carbon dot-based covalent organic framework (CD-COF) was prepared using aldehyde-based carbon dots (CDs) and 1,3,5-tris (4-aminophenyl) benzene (TPB). Because the CD-COF made the regular arrangement of CDs conducive to improving the ECL response, CD-COF had a higher ECL intensity and efficiency than CDs. What's more, the ECL intensity of the CD-COF/S2O82−/Bu4N+ system was about 2.98, 7.50, and 28.08 times higher than those of the CD-COF/S2O82−, CDs/S2O82− and S2O82− systems, respectively. Considering the remarkable ECL performance, the CD-COF/S2O82−/Bu4N+ system was employed combined with the CRISPR/Cas12a trans-cutting strategy to construct an "off–on" ECL biosensor for BPA detection. The proposed ECL biosensor exhibited excellent performance with a wide linear range from 1.0 × 10−14 mol L−1 to 1.0 × 10−5 mol L−1 with a low detection limit of 2.21 fM (S/N = 3) under the optimized conditions. The biosensor demonstrated that CD-COF can be used as an efficient ECL emitter, thus expanding the application field of COFs. In addition, the good stability and specificity of the biosensor enabled the rapid detection of BPA, which will provide valuable insights into promising ultrasensitive ECL biosensors. [ABSTRACT FROM AUTHOR]

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]

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]