Our previous studies have demonstrated that stable microRNAs (miRNAs) in mammalian serum and plasma are actively secreted from tissues and cells and can serve as a novel class of biomarkers for diseases, and act as signaling molecules in intercellular communication. Here, we report the surprising finding that exogenous plant miRNAs are present in the sera and tissues of various animals and that these exogenous plant miRNAs are primarily acquired orally, through food intake. MIR168a is abundant in rice and is one of the most highly enriched exogenous plant miRNAs in the sera of Chinese subjects. Functional studies in vitro and in vivo demonstrated that MIR168a could bind to the human/mouse low-density lipoprotein receptor adapter protein 1 (LDLRAP1) mRNA, inhibit LDLRAP1 expression in liver, and consequently decrease LDL removal from mouse plasma. These findings demonstrate that exogenous plant miRNAs in food can regulate the expression of target genes in mammals.

Far-red and near-infrared (NIR) fluorescent materials possessing the characteristics of strong two-photon absorption and aggregation-induced emission (AIE) as well as specific targeting capability are much-sought-after for bioimaging and therapeutic applications due to their deep penetration depth and high resolution. Herein, a series of dipolar far-red and NIR AIE luminogens with a strong push-pull effect are designed and synthesized. The obtained fluorophores display bright far-red and NIR solid-state fluorescence with a high quantum yield of up to 30%, large Stokes shifts of up to 244 nm, and large two-photon absorption cross-sections of up to 887 GM. A total of three neutral AIEgens show specific lipid droplet (LD)-targeting capability, while the one with cationic and lipophilic characteristics tends to target the mitochondria specifically. All of the molecules demonstrate good biocompatibility, high brightness, and superior photostability. They also serve as efficient two-photon fluorescence-imaging agents for the clear visualization of LDs or mitochondria in living cells and tissues with deep tissue penetration (up to 150 μm) and high contrast. These AIEgens can efficiently generate singlet oxygen upon light irradiation for the photodynamic ablation of cancer cells. All of these intriguing results prove that these far-red and NIR AIEgens are excellent candidates for the two-photon fluorescence imaging of LDs or mitochondria and organelle-targeting photodynamic cancer therapy.

Carbon monoxide oxidation is one of the most studied heterogeneous reactions, being scientifically and industrially important, particularly for removal of CO from exhaust streams [1] and preferential oxidation for hydrogen purification in fuel-cell applications.[2] The precious metals Ru, Rh, Pd, Pt, and Au are most commonly used for this reaction because of their high activity and stability. Despite the wealth of experimental and theoretical data, it remains unclear what is the active surface for CO oxidation under catalytic conditions for these metals. Herein we utilize in situ synchrotron ambient pressure X-ray photoelectron spectroscopy (APXPS) to monitor the oxidation state at the surface of rhodium nanoparticles (Rh NPs) during CO oxidation and demonstrate that the active catalyst is a surface oxide, the formation of which is dependent on particle size. The amount of oxide formed and the reaction rate both increase with decreasing particle size.Many single-crystal CO oxidation studies over rhodium suggest that the reaction is structure-insensitive and that the oxide formation decreases the reaction rate. [3,4] However, recent advances in synthetic techniques and in-situ experimentation have revealed that the oxidation state and stoichiometry of the surface oxide greatly affects CO oxidation rates.[5-9] At low temperatures or low O 2 /CO ratios, CO strongly adsorbs onto the catalyst surface and inhibits O 2 adsorption. At high temperatures or high O 2 /CO ratios, the catalyst surface becomes saturated with oxygen atoms and the reaction proceeds more rapidly. It has been demonstrated that small palladium nanoparticles [6] are more active for CO oxidation than larger particles and single crystals, whereas the opposite is reported for platinum.[10] For Rh NPs, no particle size effect was observed for supported rhodium catalysts,[11] but a strong particle size dependence was observed for CO desorption, dissociation, and transient CO oxidation over electron-beam-prepared Rh NPs that were precovered with oxygen. [12,13] For this investigation we have prepared small, polymerstabilized Rh NPs with a narrow size distribution and studied CO oxidation; polymer stabilized NP syntheses enable control of NP size, shape, and/or composition for reaction studies. [14,15] The turnover frequency (TOF) for CO oxidation at 200 8C increases five-fold, and the apparent activation energy decreases from 27.9 kcal mol À1 to 19.0 kcal mol À1 as the particle size decreases from 11 nm to 2 nm. APXPS of 2 nm and 7 nm Rh NP films during CO oxidation at about 1 Torr provides the first in-situ measurement of the oxidation state of Rh NPs during CO oxidation and demonstrates that smaller particles are more oxidized than larger particles during reaction at 150-200 8C. A surface oxygen species is also observed during CO oxidation that is not present when heating in O 2 alone, possibly indicating a unique active oxide phase on Rh NPs. This oxide phase may alter the relative bonding geometries of CO and/or oxygen on the rhodium surface, thereby ...

Although photodynamic therapy (PDT) has thrived as a promising treatment, highly active photosensitizers (PSs) and intense light power can cause treatment overdose. However, extra therapeutic response probes make the monitoring process complicated, ex situ and delayed. Now, this challenge is addressed by a self-reporting cationic PS, named TPE-4EP+, with aggregation-induced emission characteristic. The molecule undergoes mitochondria-to-nucleus translocation during apoptosis induced by PDT, thus enabling the in situ real-time monitoring via fluorescence migration. Moreover, by molecular charge engineering, we prove that the in situ translocation of TPE-4EP+ is mainly attributed to the enhanced interaction with DNA imposed by its multivalent positive charge. The ability of PS to provide PDT with real-time diagnosis help control the treatment dose that can avoid excessive phototoxicity and minimize potential side effect. Future development of new generation of PS is envisioned.

Recent breakthroughs in synthesis in nanoscience have achieved control of size and composition of nanoparticles that are relevant for catalyst design. Here, we show that the catalytic activity of CO oxidation by Rh/Pt bimetallic nanoparticles can be changed by varying the composition at a constant size (9+/-1 nm). Two-dimensional Rh/Pt bimetallic nanoparticle arrays were formed on a silicon surface via the Langmuir-Blodgett technique. Composition analysis with X-ray photoelectron spectroscopy agrees with the reaction stoichiometry of Rh/(Pt+Rh). CO oxidation rates that exhibit a 20-fold increase from pure Pt to pure Rh show a nonlinear increase with surface composition of the bimetallic nanoparticles that is consistent with the surface segregation of Pt. The results demonstrate the possibility of controlling catalytic activity in metal nanoparticle-oxide systems via tuning the composition of nanoparticles with potential applications for nanoscale design of industrial catalysts.

Size-tunable monodisperse Rh nanocrystals can offer unique properties for many heterogeneous catalytic reactions (such as hydrogenation, hydroformylation, and hydrocarbonylation) of both scientific and technological interest. In this article, we report the synthesis of monodisperse, well-shaped Rh nanocrystals in a range of 5-15 nm by a one-step polyol reduction at temperatures of 170-230 °C under Ar, using rhodium(III) acetylacetonate [Rh(acac) 3 ] as the source of metal ions, 1,4-butanediol as the reducing solvent, and poly-(vinylpyrrolidone) as the capping agent. Two-dimensional projects of the nanocrystals are polygons, dominated by hexagons, pentagons, and triangles with catalytically active (111) surfaces (>65% yield). Over 45% of the polygons are multiple (111) twinned particles (hexagons and pentagons), favored by thermodynamics. To achieve size uniformity, adjustment of the reduction kinetics of Rh(acac) 3 in the nucleation and crystal growth stages has been shown to depend upon several synthetic parameters including an Ar or air atmosphere, reaction temperature and time, and Rh(acac) 3 concentration. Due to the present well-controlled polyol reduction kinetics, the size of the Rh nanocrystals can be tuned by changing the Rh(acac) 3 concentration in a proper range. Monolayer films of the Rh polygons have been formed on silicon wafers by the Langmuir-Blodgett method and have been used as model heterogeneous catalysts for the study of ethylene hydrogenation.

CO oxidation is one of the most studied heterogeneous reactions, being scientifically and industrially important, particularly for removal of CO from exhaust streams' 1 ' and preferential oxidation for hydrogen purification in fuel cell applications' 21. The precious metals Ru, Rh, Pd, Pt, and Au are most commonly used for this reaction because of their high activity and stability. Despite the wealth of experimental and theoretical data, it remains unclear what is the active surface for CO oxidation under catalytic conditions for these metals. In this communication, we utilize in situ synchrotron ambient pressure X-ray photoelectron spectroscopy (APXPS) to monitor the oxidation state at the surface of Rh nanoparticles during CO oxidation and demonstrate that the active catalyst is a surface oxide, the formation of which is dependent on particle size. The amount of oxide formed and the reaction rate both increase with decreasing particle size.Many single crystal CO oxidation studies over Rh suggest that the reaction is structure insensitive and that oxide formation decreases the reaction rate.' 3 ' 4I However, recent advances in synthetic techniques and in situ experimentation have revealed that the oxidation state and stoichiometry of the surface oxide greatly affects CO oxidation rates.' 5 ' 91 At low temperatures or low 0 2 /CO ratios, CO strongly adsorbs to the catalyst surface and inhibits 0 2 adsorption. At high temperatures or high 0 2 /CO ratios, the catalyst surface becomes saturated with O atoms and the reaction proceeds more rapidly. It has been demonstrated that small nanoparticles (NPs) of Pd' 61 are more active for CO oxidation than larger particles and single crystals, while the opposite is reported in the case of Pt.' 10] For Rh NPs, no particle size effect was observed for supported Rh catalysts,' 111 but a strong particle size dependence was observed for CO desorption, dissociation, and transient CO oxidation over electron beam prepared Rh NPs precovered with oxygen. 112,13] For this investigation we have prepared small, polymer stabilized Rh NPs with a narrow size distribution and studied CO oxidation; polymer stabilized NP syntheses enable control of NP size, shape and/or composition for reaction studies.' 14 ' 15] The turnover frequency (TOF) for CO oxidation at 200 °C increases 6-fold and the apparent activation decreases from 27.9 kcal mol" 1 to 19.0 kcal mol" 1 as the particle size decreases from 11 nm to 2 nm. APXPS of 2 nm and 7 nm Rh NP films during CO oxidation near 1 Torr provides the first in situ measurement of the oxidation state of Rh NPs during CO oxidation and demonstrates that smaller particles are more oxidized than larger particles during reaction at 150 -200 °C. A surface oxygen species is also observed during CO oxidation that is not present when heating in 0 2 alone, possibly indicating a unique active oxide phase on Rh NPs. This oxide phase may alter the relative bonding geometries of CO and/or O on the Rh surface, thereby lowering the activation energy for the reaction.'...

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