Dielectric metasurfaces built up with nanostructures of high refractive index represent a powerful platform for highly efficient flat optical devices due to their easy-tuning electromagnetic scattering properties and relatively high transmission efficiencies. Here we show visible-frequency silicon metasurfaces formed by three kinds of nanoblocks multiplexed in a subwavelength unit to constitute a metamolecule, which are capable of wavefront manipulation for red, green, and blue light simultaneously. Full phase control is achieved for each wavelength by independently changing the in-plane orientations of the corresponding nanoblocks to induce the required geometric phases. Achromatic and highly dispersive meta-holograms are fabricated to demonstrate the wavefront manipulation with high resolution. This technique could be viable for various practical holographic applications and flat achromatic devices.

A highly efficient di-C-glycosyltransferase GgCGT was discovered from the medicinal plant Glycyrrhiza glabra. GgCGT catalyzes a two-step di-C-glycosylation of flopropione-containing substrates with conversion rates of >98%. To elucidate the catalytic mechanisms of GgCGT, we solved its crystal structures in complex with UDP-Glc, UDP-Gal, UDP/phloretin, and UDP/nothofagin, respectively. Structural analysis revealed that the sugar donor selectivity was controlled by the hydrogen-bond interactions of sugar hydroxyl groups with D390 and other key residues. The di-C-glycosylation capability of GgCGT was attributed to a spacious substrate-binding tunnel, and the G389K mutation could switch di- to mono-C-glycosylation. GgCGT is the first di-C-glycosyltransferase with a crystal structure, and the first C-glycosyltransferase with a complex structure containing a sugar acceptor. This work could benefit the development of efficient biocatalysts to synthesize C-glycosides with medicinal potential.

No abstract

No abstract

Novel small molecule compounds based on various scaffolds including chalcone, flavonoid, and resorcinol dibenzyl ether were designed and tested for their inhibitory activity against the Programmed Cell Death-1/Programmed Cell Death-Ligand 1 (PD-1/PD-L1) pathway. Among them, compound NP19 inhibited the human PD-1/PD-L1 interaction with IC50 values of 12.5 nM in homogeneous time-resolved fluorescence (HTRF) binding assays. In addition, NP19 dose-dependently elevated IFN-γ production in a coculture model of Hep3B/OS-8/hPD-L1 and CD3 T cells. Furthermore, NP19 displayed significant in vivo antitumor efficacy in two different mouse models of cancer (a melanoma B16-F10 tumor model and an H22 hepatoma tumor model). Moreover, H&E staining and flow cytometry data suggested that NP19 activated the immune microenvironment in the tumor, which may contribute to its antitumor effects. This work shows NP19 is a promising lead compound for further development as a new generation of small molecule inhibitors targeting the PD-1/PD-L1 pathway.

No abstract

We design and fabricate the Rochon-prism-like planar circularly polarized beam splitters based on dielectric metasurfaces by simultaneously controlling the geometric phase and the propagation phase via manipulation of the orientations and the sizes of the constituent silicon nanoblocks. The special splitters deviate only one of the circular polarizations while leave the other undeviated, acting like a Rochon prism for linearly polarized light, and their efficiencies can be as high as 66.7% with an extinction ratio of 27. The mechanism makes it possible to fabricate metasurface holograms that can only be reconstructed by either of two circular polarizations while hidden from the other. The functionality of beam splitting and polarization dependent decryption based on dielectric metasurfaces enables the potential applications in both miniaturized polarizing optical systems and information security and processing.

No abstract