Attempts are made in this study to manipulate nanostructures of Pt-flecks on Ag nanoparticles (Pt m ∧ Ag) for advanced electrocatalysts by reflux citrate reduction of Pt from Pt II Cl 4 2or Pt IV Cl 6 2ions in solution containing Ag colloids at different atomic Pt/Ag ratio (m). Characterizations with UV-vis, SERS, XPS, and XRD showed a gradual Pt covering of the Ag colloids with increasing m when Pt II Cl 4 2was the precursor of Pt (Pt m ∧ Ag-A samples). However, due to an involvement of the galvanic replacement reaction between Pt IV Cl 6 2and the metallic Ag colloids during the citrate reduction of Pt IV Cl 6 2ions, a distinct alloying of Pt with the underlying Ag particles took place at the surface region of the colloidal Ag particles when Pt IV Cl 6 2was the precursor of Pt (Pt m ∧ Ag-B samples). Cyclic voltammetry (CV) measurement of the electrochemically active surface area (EAS) showed that the Pt utilization (U Pt ) in Pt m ∧ Ag-A increased with the decrease in m. The massspecific activity (MSA) of Pt for the electrooxidation of either methanol or formic acid increased linearly with U Pt in Pt m ∧ Ag-A, but was enhanced significantly with proper Pt-Ag alloying in Pt m ∧ Ag-B catalysts. Fine-tuning the extent of Pt-Ag alloying resulted in optimized Pt m ∧ Ag-B catalyst at 0.47 e m e 0.53, whose activity by MSA of Pt was 1 order of magnitude higher in methanol electrooxidation and six times higher in formic acid electrooxidation than its Pt m ∧ Ag-A counterpart of similar U Pt .

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Conventional delivery systems for hydrophilic material still face critical challenges toward practical applications, including poor retention abilities, lack of stimulus responsiveness, and low bioavailability. Here, we propose a robust encapsulation strategy for hydrophilic cargo to produce a wide class of aqueous core–shell–shell coconut-like nanostructures featuring excellent stability and multifunctionality. The numerous active groups (−SH, −NH2, and −COOH) of the protein–polysaccharide wall material enable the formation of shell-cross-linked nanocapsules enclosing a liquid water droplet during acoustic cavitation. A subsequent pH switch can trigger the generation of an additional shell through the direct deposition of non-cross-linked protein back onto the cross-linked surface. Using anthocyanin as a model hydrophilic bioactive, these nanocapsules show high encapsulation efficiency, loading content, tolerance to environmental stresses, biocompatibility, and high cellular uptake. Moreover, the composite double shells driven by both covalent bonding and electrostatics provide the nanocapsules with pH/redox dual stimuli-responsive behavior. Our approach is also feasible for any shell material that can be cross-linked via ultrasonication, offering the potential to encapsulate diverse hydrophilic functional components, including bioactive molecules, nanocomplexes, and water-dispersible inorganic nanomaterials. Further development of this strategy should hold promise for designing versatile nanoengineered core–shell–shell nanoplatforms for various applications, such as the oral absorption of hydrophilic drugs/nutraceuticals and the smart delivery of therapeutics.

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Directly delivering liquid using direct current power was a dream for 40 years. Now, the electrokinetic pump can accomplish it. This review reports recent developments in microfabricated electrokinetic pump technologies and their applications, and also discusses the electrophoresis pump and elctroosmotic pump, as well as the materials and fabrication methods frequently used for the production of these pump devices. Electrokinetics pumps can be used to deliver pure water, pure polar organic solvents, inorganic buffer and biomacromolecules, with wide applications for the delivery of liquids. These devices have the potential to become drug delivery systems, for the precise, timed and/or targeted delivery of drugs. Future trends, limitations and possibilities are also discussed.