a b s t r a c tRecombinase polymerase amplification (RPA) is a highly sensitive and selective isothermal amplification technique, operating at 37e42 C, with minimal sample preparation and capable of amplifying as low as 1e10 DNA target copies in less than 20 min. It has been used to amplify diverse targets, including RNA, miRNA, ssDNA and dsDNA from a wide variety of organisms and samples. An ever increasing number of publications detailing the use of RPA are appearing and amplification has been carried out in solution phase, solid phase as well as in a bridge amplification format. Furthermore, RPA has been successfully integrated with different detection strategies, from end-point lateral flow strips to real-time fluorescent detection amongst others. This review focuses on the different methodologies and advances related to RPA technology, as well as highlighting some of the advantages and drawbacks of the technique.

Surfactant-assisted seeded growth of metal nanoparticles (NPs) can be engineered to produce anisotropic gold nanocrystals with high chiroptical activity through the templating effect of chiral micelles formed in the presence of dissymmetric cosurfactants. Mixed micelles adsorb on gold nanorods, forming quasihelical patterns that direct seeded growth into NPs with pronounced morphological and optical handedness. Sharp chiral wrinkles lead to chiral plasmon modes with high dissymmetry factors (~0.20). Through variation of the dimensions of chiral wrinkles, the chiroptical properties can be tuned within the visible and near-infrared electromagnetic spectrum. The micelle-directed mechanism allows extension to other systems, such as the seeded growth of chiral platinum shells on gold nanorods. This approach provides a reproducible, simple, and scalable method toward the fabrication of NPs with high chiral optical activity.

Pt nanoparticles play an essential role in a wide variety of catalytic reactions. The activity of the particles strongly depends on their three-dimensional (3D) structure and exposed facets, as well as on the reactive environment. High-resolution electron microscopy has often been used to characterize nanoparticle catalysts but unfortunately most observations so far have been either performed in vacuum and/or using conventional (2D) in situ microscopy. The latter however does not provide direct 3D morphological information. We have implemented a quantitative methodology to measure variations of the 3D atomic structure of nanoparticles under the flow of a selected gas. We were thereby able to quantify refaceting of Pt nanoparticles with atomic resolution during various oxidation–reduction cycles. In a H 2 environment, a more faceted surface morphology of the particles was observed with {100} and {111} planes being dominant. On the other hand, in O 2 the percentage of {100} and {111} facets decreased and a significant increase of higher order facets was found, resulting in a more rounded morphology. This methodology opens up new opportunities toward in situ characterization of catalytic nanoparticles because for the first time it enables one to directly measure 3D morphology variations at the atomic scale in a specific gaseous reaction environment.

We report the colloidal synthesis of a series of surfactant-stabilized lead chalcohalide nanocrystals. Our work is mainly focused on Pb 4 S 3 Br 2 , a chalco-halide phase unknown to date that does not belong to the ambient-pressure PbS-PbBr 2 phase diagram. The Pb 4 S 3 Br 2 nanocrystals herein feature a remarkably narrow size distribution (with a size dispersion as low as 5%) a good size tunability (from 7 to ∼30 nm), an indirect bandgap, photoconductivity (responsivity = 4 ± 1 mA/W) and stability for months under air. A crystal download file view on ChemRxiv 200401-PbBrS Main Text.pdf (7.35 MiB) download file view on ChemRxiv 200401-PbBrS SI.pdf (23.19 MiB) download file view on ChemRxiv Pb4S3Br2_DFT.cif (1.57 KiB) download file view on ChemRxiv Pb4S3Br2_Rietveld.cif (0.96 KiB) download file view on ChemRxiv Pb3S2Cl2_Rietveld.cif (2.31 KiB) download file view on ChemRxiv Movie_S2.avi (10.05 MiB) download file view on ChemRxiv Movie_S3.avi (8.13 MiB) download file view on ChemRxiv Movie_S1.avi (45.89 MiB)

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