Plasmonic Photothermal Gold Bipyramid Nanoreactors for Ultrafast Real-Time Bioassays.

Nucleic acid amplification techniques have been among the most powerful tools for biological and biomedical research, and the vast majority of the bioassays rely on thermocycling that uses time-consuming and expensive Peltier-block heating. Here, we introduce a plasmonic photothermal method for quantitative real-time PCR, using gold bipyramids and light to achieve ultrafast thermocycling. Moreover, we successfully extend our photothermal system to other biological assays, such as isothermal nucleic acid amplification and restriction enzyme digestion.

Creating complex molecular topologies by configuring DNA four-way junctions.

The realization of complex topologies at the molecular level represents a grand challenge in chemistry. This necessitates the manipulation of molecular interactions with high precision. Here we show that single-stranded DNA (ssDNA) knots and links can be created by utilizing the inherent topological properties that pertain to the DNA four-way junction, at which the two helical strands form a node and can be configured conveniently and connected for complex topological construction. Using this strategy, we produced series of ssDNA topoisomers with the same sequences. By finely designing the curvature and torsion, double-stranded DNA knots were accessed by hybridizing and ligating the complementary strands with the knotted ssDNA templates. Furthermore, we demonstrate the use of a constructed ssDNA knot both to probe the topological conversion catalysed by DNA topoisomerase and to study the DNA replication under topological constraint.

Live Cell MicroRNA Imaging Using Cascade Hybridization Reaction.

Recent advances in RNA research have posed new directives in biology and chemistry to uncover the complex roles of ribonucleic acids in cellular processes. Innovative techniques to visualize native RNAs, particularly, short, low-abundance RNAs in live cells, can dramatically impact current research on the roles of RNAs in biology. Herein, we report a novel method for real-time, microRNA imaging inside live cells based on programmable oligonucleotide probes, which self-assemble through the Cascade Hybridization Reaction (CHR).