Surface-Plasmon-Induced Visible Light Photocatalytic Activity of TiO₂ Nanospheres Decorated by Au Nanoparticles with Controlled Configuration

This work is focused on the development of a surface plasmon-induced visible light active photocatalyst system composed of silica–titania core–shell (SiO₂@TiO₂) nanostructures decorated with Au nanoparticles (Au NPs). The influence of size and distribution of Au NPs on photocatalysis, its fabrication methods, and exploration of the mechanism of visible light activity were investigated. A favorable architecture of SiO₂ beads with a thin layer of TiO₂ was decorated with Au NP arrays having different size and areal density. Surface modification of SiO₂@TiO₂ leads to a viable and homogeneous loading of Au NPs on the surface of TiO₂, which renders visible light-induced photocatalytic activity on the whole TiO₂ surface. An optimized system employing Au NP arrays with 15 nm size and 700/μm² density showed best catalytic efficiency due to a synergistic effect of the firm contact between Au NPs and TiO₂ and efficiently coupled SPR excitation. A brief mechanism relating the electron transfer from surface-plasmon-stimulated Au NPs to the conduction band of TiO₂ is proposed

Continuous Recycling of Homogeneous Pd/Cu Catalysts for Cross-Coupling Reactions

Given the importance of homogeneous catalysts recycling in organic chemistry, we have developed a unique microfluidic loop system for automated continuous recirculation of a soluble polymer supported metal catalyst for novel isocyanide cross-coupling reactions under thermomorphic multicomponent solvent (TMS) conditions. Our system provides an innovative approach for the chemical library synthesis of quinazolinone derivatives as well as an important intermediate of Merck’s LTD4 antagonist “Singulair” with efficient continuous homogeneous catalyst recycling

Ratiometric Fluorescent Polymeric Thermometer for Thermogenesis Investigation in Living Cells

Intracellular temperature has a fundamental effect on cellular events. Herein, a novel fluorescent polymer ratiometric nanothermometer has been developed based on transferrin protein-stabilized gold nanoclusters as the targeting and fluorescent ratiometric unit and the thermosensitve polymer as the temperature sensing unit. The resultant nanothermometer could feature a high and spontaneous uptake into the HeLa cells and the ratiometric temperature sensing over the physiological temperature range. Moreover, the precise temperature sensing for intracellular heat generation in HeLa cells following calcium ions stress has been achieved. This practical intracellular thermometry could eliminate the interference of the intracellular surrounding environment in cancer cells without a microinjection procedure, which is user-friendly. The prepared new nanothermometer can provide tools for unveiling the intrinsic relationship between the intracellular temperature and ion channel function

Microfluidic Approach toward Continuous and Ultrafast Synthesis of Metal–Organic Framework Crystals and Hetero Structures in Confined Microdroplets

Herein, we report a novel nanoliter droplet-based microfluidic strategy for continuous and ultrafast synthesis of metal–organic framework (MOF) crystals and MOF heterostructures. Representative MOF structures, such as HKUST-1, MOF-5, IRMOF-3, and UiO-66, were synthesized within a few minutes via solvothermal reactions with substantially faster kinetics in comparison to the conventional batch processes. The approach was successfully extended to the preparation of a demanding Ru₃BTC₂ structure that requires high-pressure hydrothermal synthesis conditions. Finally, three different types of core–shell MOF composites, i.e., Co₃BTC₂@Ni₃BTC₂, MOF-5@diCH₃-MOF-5, and Fe₃O₄@ZIF-8, were synthesized by exploiting a unique two-step integrated microfluidic synthesis scheme in a continuous-flow mode. The synthesized MOF crystals were characterized by X-ray diffraction, scanning electron microscopy, and BET surface area measurements. In comparison with bare MOF-5, MOF-5@diCH₃-MOF-5 showed enhanced structural stability in the presence of moisture, and the catalytic performance of Fe₃O₄@ZIF-8 was examined using Knoevenagel condensation as a probe reaction. The microfluidic strategy allowed continuous fabrication of high-quality MOF crystals and composites exhibiting distinct morphological characteristics in a time-efficient manner and represents a viable alternative to the time-consuming and multistep MOF synthesis processes

Digital Microfluidic Approach for Efficient Electroporation with High Productivity: Transgene Expression of Microalgae without Cell Wall Removal

A unique digital microfluidic electroporation (EP) system successfully demonstrates higher transgene expression than that of conventional techniques, in addition to reliable productivity and feasible integrated processes. By systematic investigations into the effects of the droplet EP conditions for a wild-type microalgae, 1 order of magnitude higher transgene expression is accomplished without cell wall removal over the conventional bulk EP system. In addition, the newly proposed droplet EP method by a droplet contact charging phenomena shows a great potential for the integration of EP processes and on-chip cell culture providing easy controllability of each process. Finally, the implications of the accomplishments and future directions for development of the proposed technology are discussed

Reversed Janus Micro/Nanomotors with Internal Chemical Engine

Self-motile Janus colloids are important for enabling a wide variety of microtechnology applications as well as for improving our understanding of the mechanisms of motion of artificial micro- and nanoswimmers. We present here micro/nanomotors which possess a reversed Janus structure of an internal catalytic “chemical engine”. The catalytic material (here platinum (Pt)) is embedded within the interior of the mesoporous silica (mSiO₂)-based hollow particles and triggers the decomposition of H₂O₂ when suspended in an aqueous peroxide (H₂O₂) solution. The pores/gaps at the noncatalytic (Pt) hemisphere allow the exchange of chemical species in solution between the exterior and the interior of the particle. By varying the diameter of the particles, we observed size-dependent motile behavior in the form of enhanced diffusion for 500 nm particles, and self-phoretic motion, toward the nonmetallic part, for 1.5 and 3 μm ones. The direction of motion was rationalized by a theoretical model based on self-phoresis. For the 3 μm particles, a change in the morphology of the porous part is observed, which is accompanied by a change in the mechanism of propulsion <i>via</i> bubble nucleation and ejection as well as a change in the direction of motion

One-Pot Defunctionalization of Lignin-Derived Compounds by Dual-Functional Pd₅₀Ag₅₀/Fe₃O₄/N-rGO Catalyst

Generation of hydrogen from renewable sources and its safe utilization for efficient one-pot upgrading of renewable biofuels are a challenge. Bimetallic PdAg catalyst supported on Fe₃O₄/nitrogen-doped reduced graphene oxide (N-rGO) were synthesized for hydrogen generation from formic acid with high TOF (497 h^–1 at 50 °C), and the hydrogen was subsequently utilized in situ for selective defunctionalization of lignin-derived chemicals with preserved aromatic nature at ambient pressure. Hydrodeoxygenation of aromatic aldehydes and ketones gave excellent yields (99% at 130 °C) with no use of additives. Furthermore, hydrogenolysis of β-O-4 and α-O-4 C–O model compounds produced only two products with high selectivity at 120 °C, which is an efficient and versatile one-pot platform for valorization of lignin biomass