Highly Sensitive Detection of miR-21 through Target-Activated Catalytic Hairpin Assembly of X-Shaped DNA Nanostructures.

MicroRNAs (miRNAs) are found in extremely low concentrations in cells, so highly sensitive quantitation is a great challenge. Herein, a simple dual-amplification strategy involving target-activated catalytic hairpin assembly (CHA) coupled with multiple fluorophores concentrated on one X-shaped DNA is reported. In this strategy, four hairpin probes (H1, H2, H3, and H4) are modified with FAM and BHQ1 at both sticky ends, while a circulating hairpin probe (H0) is used to activate CHA circuits once it binds to complementary sequences in the target miR-21 (T).

Dual Energy Transfer-Based Fluorescent Nanoprobe for Imaging miR-21 in Nonalcoholic Fatty Liver Cells with Low Background.

Nonalcoholic fatty liver disease (NAFLD) can progress gradually to liver failure, early warning of which is critical for improving the cure rate of NAFLD. In situ imaging and monitoring of overexpressed miR-21 is an advanced strategy for NAFLD diagnosis. However, this strategy usually suffers from the high background imaging in living cells owing to the complexity of the biological system.

Dy(III)-induced aggregation emission quenching effect of single-layered graphene quantum dots for selective detection of phosphate in the artificial wetlands.

Carbon quantum dots (CQDs), prepared by one-step hydrothermal treatment of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and triethylamine (TEA), could be exfoliated or delaminated into single-layered graphene quantum dots (s-GQDs) with methanol for the first time, with fluorescence (FL) emission at 500 nm when excited at 417 nm. The s-GQDs, with more sufficient carboxyl groups on the surface than CQDs, could be induced to be aggregated by metal ion dysprosium (Dy), resulting in aggregation-induced emission quenching effect subsequently. However, the presence of phosphate (PO) destroys the Dy-induced aggregates of s-GQDs owing to the strong coordination between Dy and PO, inducing the FL emission recovery of the s-GQDs and providing selective detection method of PO in the artificial wetlands with the linear range of 0.