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Abstract Background Small interfering RNA (siRNA) has emerged as a kind of promising therapeutic agents for cancer therapy. However, the off-target effect and degradation are the main challenges for siRNAs delivery. Herein, an enzyme-free DNA amplification strategy initiated by a specific endogenous microRNA has been developed for in situ generation of siRNAs with enhanced gene therapy effect on cervical carcinoma. Methods This strategy contains three DNA hairpins (H1, H2/PS and H3) which can be triggered by microRNA-21 (miR-21) for self-assembly of DNA nanowheels (DNWs). Notably, this system is consistent with the operation of a DNA logic circuitry containing cascaded “AND” gates with feedback mechanism. Accordingly, a versatile biosensing and bioimaging platform is fabricated for sensitive and specific analysis of miR-21 in HeLa cells via fluorescence resonance energy transfer (FRET). Meanwhile, since the vascular endothelial growth factor (VEGF) antisense and sense sequences are encoded in hairpin reactants, the performance of this DNA circuit leads to in situ assembly of VEGF siRNAs in DNWs, which can be specifically recognized and cleaved by Dicer for gene therapy of cervical carcinoma. Results The proposed isothermal amplification approach exhibits high sensitivity for miR-21 with a detection limit of 0.25 pM and indicates excellent specificity to discriminate target miR-21 from the single-base mismatched sequence. Furthermore, this strategy achieves accurate and sensitive imaging analysis of the expression and distribution of miR-21 in different living cells. To note, compared to naked siRNAs alone, in situ siRNA generation shows a significantly enhanced gene silencing and anti-tumor effect due to the high reaction efficiency of DNA circuit and improved delivery stability of siRNAs. Conclusions The endogenous miRNA-activated DNA circuit provides an exciting opportunity to construct a general nanoplatform for precise cancer diagnosis and efficient gene therapy, which has an important significance in clinical translation. Graphic abstract

Two-dimensional quantum dots (2D-QDs) derived from two-dimensional sheets have received increasing interest owing to their unique properties, such as large specific surface areas, abundant active sites, good aqueous dispersibility, excellent electrical property, easy functionalization, and so on. A variety of 2D-QDs have been developed based on different materials including graphene, black phosphorus, nitrides, transition metal dichalcogenides, transition metal oxides, and MXenes. These 2D-QDs share some common features due to the quantum confinement effects and they also possess unique properties owing to their structural differences. In this review, we discuss the categories, properties, and synthetic routes of these 2D-QDs and emphasize their applications in electrochemical biosensors. We deeply hope that this review not only stimulates more interest in 2D-QDs, but also promotes further development and applications of 2D-QDs in various research fields.

In the molecule of the title compound, C11H15N5OS2, the thiadiazole and triazole rings are not coplanar, the dihedral angle formed by their mean planes being 59.9 (2)°. The exocyclic S atom, and the methylene, carbonyl, tert-butyl and one methyl carbon form an approximately planar zigzag chain, which makes a dihedral angle of 74.6 (1)° with the thiadiazole ring.

In the molecule of the title compound, C23H18BrN3O3, the benzotriazole mean plane makes dihedral angles of 1.26 (1) and 87.39 (1)° with the tolyl and bromophenyl benzene rings, respectively, and the dihedral angle between the benzene rings is 87.27 (1)°. In the crystal structure, molecules are linked into chains along the a axis by C—H...O intermolecular hydrogen bonds. The structure is further stabilized by C—H...π and π–π interactions, with a distance of 3.700 (1) Å between the centroids of the bromophenyl and benzotriazole benzene rings related by symmetry code (x, −1 + y, z).

Variation in leaf traits is critical for carbon gains and losses during leaf life and drives litter carbon and nutrient losses via decomposition. Accurately quantifying litter decomposition parameters is essential for assessing ecosystem carbon and nutrient dynamics. Leaf litterbags have commonly been employed to measure effects of environmental drivers, decomposers, and plant traits on decomposition rates. There has been much debate regarding the suitability of substituting senesced dead leaves with fresh (green) leaves in litterbags, which has been common practice for mimicking green leaf fall or for practical reasons. Therefore, we tested the null hypothesis that replacement of dead leaves with fresh leaves in litterbag experiments is justified, based on similarities in structural and chemical traits between fresh and dead leaves across plant species and growth forms.We conducted a paired litterbag decomposition experiment with both fresh and dead leaves of 26 common species in subtropical China, in each of five contrasting ecosystems.While fresh leaves generally decomposed faster than dead leaves, this deviation varied among species and growth forms, based on their traits. Overall, there was significant but rather weak correlation between dead leaf decomposition rate k and fresh leaf k, across species and ecosystem types; the deviation between fresh and dead leaf k was larger for fast‐decomposing, mostly herbaceous species. The different decomposition patterns for fresh versus dead leaves were underpinned by key underlying traits integrated in leaf resource economics spectra (LES) for fresh and dead leaves. The dead leaf LES exhibited a greater predictive capability for dead leaf k while the fresh leaf LES had higher explanatory value for the fresh leaf k values.Our findings partly reject the null hypothesis and ask for caution in inferring leaf litter decomposition rates based on green leaf litterbags or traits data. We suggest follow‐up research on substituting senesced roots and stems with fresh ones in decomposition experiments.Synthesis. Human activities and extreme weather events are leading to increasing pulse inputs of fresh plant parts and our study contributes to knowledge on how they contribute to overall decomposition rates besides senesced litter inputs. [ABSTRACT FROM AUTHOR]