Engineering modular platforms to control biomolecular architecture can advance both the understanding and the manipulation of biological systems. Icosahedral particles uniformly displaying single antigens stimulate potent immune activation and have been successful in various licensed vaccines. However, it remains challenging to display multiple antigens on a single particle and to induce broader immunity protective across strains or even against distinct diseases. Here, we design a dually addressable synthetic nanoparticle by engineering the multimerizing coiled-coil IMX313 and two orthogonally reactive split proteins. SpyCatcher protein forms an isopeptide bond with SpyTag peptide through spontaneous amidation. SnoopCatcher forms an isopeptide bond with SnoopTag peptide through transamidation. SpyCatcher-IMX-SnoopCatcher provides a modular platform, whereby SpyTag-antigen and SnoopTag-antigen can be multimerized on opposite faces of the particle simply upon mixing. We demonstrate efficient derivatization of the platform with model proteins and complex pathogen-derived antigens. SpyCatcher-IMX-SnoopCatcher was expressed in Escherichia coli and was resilient to lyophilization or extreme temperatures. For the next generation of malaria vaccines, blocking the transmission of the parasite from human to mosquito is an important goal. SpyCatcher-IMX-SnoopCatcher multimerization of the leading transmission-blocking antigens Pfs25 and Pfs28 greatly enhanced the antibody response to both antigens in comparison to the monomeric proteins. This dual plug-and-display architecture should help to accelerate vaccine development for malaria and other diseases.

In an atomically thin-film/dielectric-substrate heterostructure, the elemental physical properties of the atomically thin-film are influenced by the interaction between the thin-film and the substrate. In this article, utilizing monolayer MoS(2) on LaAlO(3) and SrTiO(3) substrates, as well as SiO2 and Gel-film as reference substrates similar to previously reported work [Nano Res, 2014, 7, 561], we systematically investigate the substrate effect on the photoluminescence of monolayer MoS(2). We observed significantly substrate-dependant photoluminescence of monolayer MoS(2), originating from substrate-to-film charge transfer. We found that SiO2 substrate introduces the most charge doping while SrTiO(3) introduces less charge transfer. Through the selection of desired substrate, we are able to induce different amounts of charge into the monolayer MoS(2), which consequently modifies the neutral exciton and charged exciton (trion) emissions. Finally, we proposed a band-diagram model to elucidate the relation between charge transfer and the substrate Fermi level and work function. Our work demonstrates that the substrate charge transfer exerts a strong influence on the monolayer MoS(2) photoluminescence property, which should be considered during device design and application. The work also provides a possible route to modify the thin-film photoluminescence property via substrate engineering for future device design.

Polerovirus P0 suppressors of host gene silencing contain a consensus F-box-like motif with Leu/Pro (L/P) requirements for suppressor activity. The Inner Mongolian Potato leafroll virus (PLRV) P0 protein (P0(PL-IM)) has an unusual F-box-like motif that contains a Trp/Gly (W/G) sequence and an additional GW/WG-like motif (G139/W140/G141) that is lacking in other P0 proteins. We used Agrobacterium infiltration-mediated RNA silencing assays to establish that P0(PL-IM) has a strong suppressor activity. Mutagenesis experiments demonstrated that the P0(PL-IM) F-box-like motif encompasses amino acids 76-LPRHLHYECLEWGLLCG THP-95, and that the suppressor activity is abolished by L76A, W87A, or G88A substitution. The suppressor activity is also weakened substantially by mutations within the G139/W140/G141 region and is eliminated by a mutation (F220R) in a C-terminal conserved sequence of P0(PL-IM). As has been observed with other P0 proteins, P0(PL-IM) suppression is correlated with reduced accumulation of the host AGO1-silencing complex protein. However, P0(PL-IM) fails to bind SKP1, which functions in a proteasome pathway that may be involved in AGO1 degradation. These results suggest that P0(PL-IM) may suppress RNA silencing by using an alternative pathway to target AGO1 for degradation. Our results help improve our understanding of the molecular mechanisms involved in PLRV infection.

The traditional design strategies for highly bright solid‐state luminescent materials rely on weakening the intermolecular π–π interactions, which may limit diversity when developing new materials. Herein, we propose a strategy of tuning the molecular packing mode by regioisomerization to regulate the solid‐state fluorescence. TBP‐e‐TPA with a molecular rotor in the end position of a planar core adopts a long‐range cofacial packing mode, which in the solid state is almost non‐emissive. By shifting molecular rotors to the bay position, the resultant TBP‐b‐TPA possesses a discrete cross packing mode, giving a quantum yield of 15.6±0.2 %. These results demonstrate the relationship between the solid‐state fluorescence efficiency and the molecule's packing mode. Thanks to the good photophysical properties, TBP‐b‐TPA nanoparticles were used for two‐photon deep brain imaging. This molecular design philosophy provides a new way of designing highly bright solid‐state fluorophores.

A metal catalyst supported on an inert substrate could consist of both metal nanoparticles and singly dispersed metal atoms. Whether these singly dispersed metal atoms are active and how different their catalytic mechanism could be in contrast to a supported metal catalyst are fundamentally important for understanding catalysis on a supported metal or oxide. By taking reduction of NO with CO on singly dispersed Rh atoms anchored on an inert support SiO2 as a probe system (Rh1/SiO2), here we demonstrated how singly dispersed metal atoms on an inert support could perform a complex multi-step catalytic cycle through a mechanism distinctly different from that for a supported metal nanoparticle with continuously packed metal sites. These singly dispersed Rh1 atoms anchored on SiO2 are active in reducing nitric oxide with carbon monoxide through two reaction pathways that are different from those of Rh nanoparticles. In situ IR studies show that a CO molecule and a NO molecule coadsorb on a singly dispersed Rh atom, Rh1 anchored on SiO2, and couple to form an N atom to adsorb on the surface and a CO2 molecule to desorb. The adsorbed N atom further couples with another CO molecule in the gas phase to form an intermediate −NCO on Rh1; this intermediate can directly couple with an NO molecule adsorbed on the same Rh1 to form N2 and CO2. In another pathway, the adsorbed N atom can couple with a coadsorbed NO on the same Rh1 to form N2O; N2O further reacts with adsorbed CO on the same Rh1 to form N2 and CO2 through a high activation barrier that can be overcome at a high temperature. Our studies show that the singly dispersed metal atoms on an inert support have great potential to perform selective transformation of chemicals. The confirmed catalysis with a singly dispersed Rh1 on SiO2 through a mechanism different from a metal nanoparticle supported on the same substrate suggests the significance of taking the single-atom catalysis (SAC) into fundamental studies of catalysis of a supported metal catalyst, since metal nanoparticles and singly dispersed metal atoms likely coexist on the inert support of many supported catalysts.

Activatable second near‐infrared window (NIR‐II; 1.0–1.7 µm) fluorescence probes that uncage deep‐tissue penetrating fluorescence by disease‐related biomarker stimuli hold great promise for detecting diseases with a poor understanding of the pathology at the molecular level with unprecedented resolution. However, currently, very few activatable NIR‐II fluorescence probes are reported mainly due to the lack of a simple yet general design strategy. Herein, a new and fairly generic design strategy using a bio‐erasable intermolecular donor–acceptor interaction to construct activatable NIR‐II fluorescence probes is reported. An organic semiconducting nanoprobe (SPNP) is constructed through blending a biomarker‐sensitive organic semiconducting non‐fullerene acceptor (3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐cyclopentane‐1,3‐dione‐[c]thiophen))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2',3'‐d']‐s‐indaceno[1,2‐b:5,6‐b'] dithiophene) (ITTC) (one of electric acceptors in organic solar cells) with a biomarker‐inert semiconducting polymer donor 5‐(4,8‐bis((2‐ethylhexyl)oxy)‐6‐methylbenzo[1,2‐b:4,5‐b']difuran‐2‐yl)‐10‐methylnaphtho[1,2‐c:5,6‐c']bis([1,2,5]thiadiazole) (PDF) in an amphiphilic‐polymer‐coated single nanoparticle to suppress NIR‐II fluorescence of the donor via a intermolecular donor–acceptor interaction. The acceptor ITTC is found to be specifically degraded by hypochlorite (an important biomarker) to erase its acceptor property, thus erasing the intermolecular donor–acceptor interaction and uncaging NIR‐II fluorescence. Consequently, SPNP exhibits a 17.5‐fold higher fluorescence brightness in the hypochlorite‐abnormal inflammation in vivo than in normal tissues. Our bio‐erasable intermolecular donor–acceptor interaction strategy provides simple yet general guidelines to design various biomarker‐activatable NIR‐II fluorescence probes.

In this paper, the thermodynamic parameters such as Grüneisen parameters and anharmonicity are investigated utilizing pressure- and temperature-dependent Raman spectroscopy of monolayer transition-metal dichalcogenides MX2 (M = Mo, W; X = S, Se). The result indicates a good stability of these compounds in the pressure range of 0–9.0 GPa and the temperature range of 175–575 K. It is a general trend that Raman mode varies with temperature and pressure linearly for monolayer MX2, and the thermodynamic Grüneisen parameters can be determined from the temperature- and pressure-dependencies of Raman spectra. Based on these measurable parameters, anharmonic parameters are extracted for each active Raman mode. The result shows that the temperature dependencies of the phonon frequencies are well described by considering the contributions from thermal expansion and lattice anharmonicity.

A series of 4-N,N-dimethylaminoaniline salicylaldehyde Schiff-base derivatives (DAS) were facilely prepared. They exhibit typical AIE properties with various fluorescence emissions and high fluorescence quantum yields in an aggregated state. DAS exhibit unique pH-dependent optical properties, which indicated their potential applications in pH sensing.