Yuan Pu

Green synthesis of highly dispersed ytterbium and thulium co-doped sodium yttrium fluoride microphosphors for in situ light upconversion from near-infrared to blue in animals

We report a simple, low cost and environmentally friendly method to prepare NaYF4:Yb3+, Tm3+ upconversion microphosphors (UCMPs) by thermal decomposition of rare earth-trifluoroacetate precursors using paraffin as the high boiling non-coordinating solvent. The UCMPs exhibited cubic phase with defined shape and bright upconversion luminescence. After coating with amphiphilic polymers of phospholipid-polyethylene glycol, the NaYF4:Yb3+, Tm3+ UCMPs were highly dispersed in aqueous solutions and exhibited low cytotoxicity. Furthermore, we explored the use of the micro-injected micro-sized NaYF4:Yb3+, Tm3+ particles for converting of near infrared into blue light in mice brain. The in vivo macroscopic upconversion luminescence imaging results showed that UCMPs located at 1mm depth in the brain could be clearly distinguished. Microscopic upconversion luminescence imaging of the brain sections in vitro revealed that the UCMPs embedded at the particular location in brain tissues of mice were stable without significant diffusion in two weeks.

Synthesis of monodisperse iron oxide nanoparticles without surfactants

Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3ċH2O were used as two precipitants for comparison. The average size of nanoparticles with NH3ċH2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

Polyhedral oligomeric silsesquioxane-coated nanodiamonds for multifunctional applications

Polyhedral oligomeric silsesquioxane (POSS)-coated nanodiamonds (NDs@POSS) were prepared via the amide formation between amine-functionalized POSS and oxygen-containing groups of NDs. The POSS structures grafted on the surface of NDs enable the NDs@POSS nanocomposites to be well-dispersed in organic solvents and polymers for multifunctional applications. The surface coating of NDs with POSS also bring other incidental advantages such as enhanced thermal stability and superhydrophobic of the NDs. NDs@POSS nanocomposites-embedded hybrid films based on polycarbonate and polyvinyl butyral were fabricated by solution blending methods, showing tunable refractive indexes in the range of 1.49–1.61. Furthermore, the powders of NDs@POSS were superhydrophobic with contact angle of water/air of 154°. Liquid marbles formed by coating the water droplet with NDs@POSS were prepared, and the process intensification effects of the NDs@POSS-based miniature reactors for degradation of methylene and fabrication of Ag nanoparticles were also demonstrated, respectively.

Recent advances on metal-free graphene-based catalysts for the production of industrial chemicals

AbstractWith the development of carbon catalysts, graphene-based metal-free catalysts have drawn increasing attention in both scientific research and in industrial chemical production processes. In recent years, the catalytic activities of metal-free catalysts have significantly improved and they have become promising alternatives to traditional metal-based catalysts. The use of metal-free catalysts greatly improves the sustainability of chemical processes. In view of this, the recent progress in the preparation of graphene-based metal-free catalysts along with their applications in catalytic oxidation, reduction and coupling reactions are summarized in this review. The future trends and challenges for the design of graphenebased materials for industrial organic catalytic reactions with good stabilities and high catalytic performance are also discussed.

Subgram-Scale Synthesis of Biomass Waste-Derived Fluorescent Carbon Dots in Subcritical Water for Bioimaging, Sensing, and Solid-State Patterning

Fluorescent carbon dots (FCDs) have received considerable attention because of the great potential for a wide range of applications, from bioimaging to optoelectronic devices. In this work, we reported the synthesis of nitrogen-doped FCDs with an average size of 2 nm in a subcritical water apparatus by using biomass waste (i.e., expired milk) as the precursor. The obtained FCDs were highly dispersed in aqueous solution because of the presence of O-containing functional groups on their surfaces. Under the excitation of ultraviolet and blue light, the FCDs exhibited excitation wavelength-dependent fluorescence in the emission range of 400–550 nm. The FCDs could be easily taken up by HeLa cells without additional surface functionalization, serving as fluorescent nanoprobes for bioimaging. The applications of FCDs as sensing agents for the detection of Fe3+, solid-state fluorescent patterning, and transparent hybrid films were also performed, demonstrating their potential for solid-state fluorescent sensing, security labeling, and wearable optoelectronics.