Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

Layered double hydroxides (LDHs) are currently attracting intense research interest for their various applications. Three LDH hollow nano-polyhedra are synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the templates. The nanocages well inherit the rhombic dodecahedral shape of the ZIF-67 templates, and the shell is composed of nanosheets assembled with an edge-to-face stacking. This is the first synthesis of the LDH non-spherical structures. And the mechanism of utilizing metal-organic framework (MOF) nanocrystals as templates is explored. Control of the simultaneous reactions, the precipitation of the shells and the template etching, is extremely crucial to the preparation of the perfect nanocages. And the Ni-Co LDH nanocages exhibit superior pseudocapacitance property due to their novel hierarchical and submicroscopic structures.

One‐nucleotide differences in microRNAs (miRNAs) can be discriminated in an assay based on a branched rolling‐circle amplification (BRCA) reaction and fluorescence quantification. With the proposed method miRNA can be detected at concentrations as low as 10 fM, and the miRNA in a total RNA sample of a few nanograms can be determined.

Tiny amounts of a given miRNA (0.1 zmol) can be detected accurately and quantitatively by a real‐time method based on an exponential amplification reaction (see picture). The proposed method has a wide dynamic range of more than 10 orders of magnitude, can be carried out within 30 minutes under isothermal conditions, and requires no modified DNA probes. It clearly discriminates miRNA sequences that differ by one base.

An ultrasensitive microRNA assay was developed with one-step loop-mediated isothermal amplification (LAMP) initiated by the target microRNA.

Matchmaker, matchmaker: A gold‐nanoparticle‐based light‐scattering assay has been developed for sensitive detection of DNA hybridization. The assay relies on the enhancement of light scattering that originates from the aggregation of oligonucleotide‐functionalized gold nanoparticles directed by the target DNA. The assay also exhibits a high degree of discrimination between perfectly matched target DNA and targets with single base‐pair mismatches.

A new enzyme-free signal amplification-based assay for microRNA (miRNA) detection is developed by using hybridization chain reaction (HCR) coupled with a graphene oxide (GO) surface-anchored fluorescence signal readout pathway. MiRNAs can efficiently initiate HCR between two species of fluorescent hairpin probes. After HCR, both of the excess hairpin probes and the HCR products will be anchored on the GO surface. The fluorescence of the hairpin probes can be completely quenched by GO, whereas the HCR products maintain strong fluorescence. Therefore, integrating HCR strategy for signal amplification with selective fluorescence quenching effects of GO provides a versatile miRNA assay.

Amorphous cobalt sulfide polyhedral nanocages are synthesized by utilizing zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as templates.