Uniform polystyrene microspheres decorated with noble metal nanoparticles formed without using extra reducing agent

Multilayered Dual Functional SiO2@Au@SiO2@QD Nanoparticles for Simultaneous Intracellular Heating and Temperature Measurement

This paper discusses synthesis and application of dual functional SiO₂@Au@SiO₂@QD composite nanoparticles for integrated intracellular heating with temperature motoring. The particles are of multilayered concentric structure, consisting of Au nanoshells covered with quantum dots, with the former for infrared heating through localized surface plasma resonance while the later for temperature monitoring. The key to integrate plasmonic-heating/thermal-monitoring on a single composite nanoparticle is to ensure that the quantum dots be separated at a certain distance away from the Au shell surface in order to ensure a detectable quantum yield. Direct attachment of the quantum dots onto the Au shell would render the quantum dots practically functionless for temperature monitoring. To integrate quantum dots into Au nanoshells, a quantum quenching barrier of SiO₂ was created by modifying a Stöber-like process. Materials, optical and thermal characterization was made of these composite nanoparticles. Cellular uptake of the nanoparticles was discussed. Experiments were performed on simultaneous in vitro heating and temperature monitoring in a cell internalized with the dual-functional SiO₂@Au@SiO₂@QD composite nanoparticles.

Thermosensitive mixed shell polymeric micelles decorated with gold nanoparticles at the outmost surface: tunable surface plasmon resonance and enhanced catalytic properties with excellent colloidal stability

Gold NPs are coupled to the outermost surface of mixed shell polymeric micelles with a PEG/PNIPAM shell, exhibit thermoresponsive surface plasmon resonance, enhanced catalytic properties and excellent colloidal stability.

Magnetically recyclable polymer single crystal supported silver nanocatalyst

We report the immobilization of unprotected silver nanoparticle on the carboxylic acid abundant polymer single crystal surface with controllable size through photogenerated chemical reduction reaction. The resulting silver nanoparticle decorated polymer single crystal not only shows higher catalytic activity as compared to its counterpart bearing surface ligand but also exhibits size-dependent catalytic activity with the smallest size (∼1.5 nm) being the most active. By further introducing iron oxide nanoparticles onto its surface, the resulting catalyst system can be magnetically recycled for up to five times with little loss in catalytic activity. These, together with the high loading originated from the high surface area to volume ratio for a polymer single crystal, make current catalyst system attractive for many industrial important catalytic applications.

Core-shell and asymmetric polystyrene-gold composite particles via one-step Pickering emulsion polymerization

Core-shell structured polystyrene-gold composite particles are synthesized from one-step Pickering emulsion polymerization. The surface coverage of the core-shell composite particles is improved with increasing gold nanoparticle (AuNP) hydrophobicity and concentration. At high surface coverage, the AuNPs exhibit an ordered hexagonal pattern, likely due to electrostatic repulsion during the emulsion polymerization process. In addition to core-shell structured polystyrene-gold composite particles, an intriguing observation is that at low AuNP concentrations, asymmetric polystyrene-gold nanocomposite particles are simultaneously formed, where a single gold nanoparticle is attached onto each polystyrene particle. It is found that these asymmetric particles are formed via a "seeded-growth" mechanism. The core-shell and asymmetric polystyrene-gold composite particles prove to be efficient catalysts as they successfully catalyze the Rhodamine B reduction reaction with stable performance and show high recyclability as catalysts.

Enhanced hematite water electrolysis using a 3D antimony-doped tin oxide electrode

We present herein an example of nanocrystalline antimony-doped tin oxide (nc-ATO) disordered macroporous "inverse opal" 3D electrodes as efficient charge-collecting support structures for the electrolysis of water using a hematite surface catalyst. The 3D macroporous structures were created via templating of polystyrene spheres, followed by infiltration of the desired precursor solution and annealing at high temperature. Using cyclic voltammetry and electrochemical impedance spectroscopy, it was determined that the use of this 3D transparent conducting oxide with a hematite surface catalyst allowed for a 7-fold increase in active surface area for water splitting with respect to its 2D planar counterpart. This ratio of surface areas was evaluated based on the presence of oxidized trap states on the hematite surface, as determined from the equivalent circuit analysis of the Nyquist plots. Furthermore, the presence of nc-ATO 2D and 3D "underlayer" structures with hematite deposited on top resulted in decreased charge transfer resistances and an increase in the number of available active surface sites at the semiconductor-liquid junction when compared to hematite films lacking any nc-ATO substructures. Finally, absorption, transmission, and reflectance spectra of all of the tested films were measured, suggesting the feasibility of using 3D disordered structures in photoelectrochemical reactions, due to the high absorption of photons by the surface catalyst material and trapping of light within the structure.

Polymer Single Crystal As Magnetically Recoverable Support for Nanocatalysts

In this Letter, we report, for the first time, using polymer single crystal as magnetically recoverable support for nanoparticle catalysts. This catalyst system is composed of polymer single crystal, platinum nanoparticles, and iron oxide nanoparticles, which act as support, catalysts, and magnetic responsive materials, respectively. Platinum nanoparticles and iron oxide nanoparticles were bonded onto thiol groups and hydroxyl groups on a tailor-designed polymer single-crystal surface. Because of its quasi 2D nature, polymer single crystal possesses high surface area to volume ratio (2.5 × 10(8) m(-1)), which is ∼40 times higher than its nanosphere counterpart of the same volume. This high surface to volume ratio facilitates the high loading of both nanoparticles, which ensures efficient catalytic reaction and reliable nanoparticle recycling. Synergetic interactions between platinum and iron oxide nanoparticles also led to further improvement in catalytic activity.

Polyamide 66 microspheres metallised with in situ synthesised gold nanoparticles for a catalytic application

A simple concept is proposed to metallise polyamide 66 (PA66) spherulite structures with in situ synthesised gold nanoparticles (Au NPs) using a wet chemical method. This cost-effective approach, applied to produce a PA66/Au NP hybrid material, offers the advantages of controlling the nanoparticle size, the size distribution and the organic-inorganic interactions. These are the key factors that have to be controlled to construct consistent Au nanostructures which are essential for producing the catalytic activities of interest. The hybrid materials obtained are characterised by means of scanning electron microscopy, transmission electron microscopy, attenuated total reflection-Fourier transform infrared spectrometry and X-ray diffraction spectrometry. The results show that PA66 microspheres obtained via the crystallisation process are coated with Au NPs of 13 nm in size. It was found that controlling the metal coordination is the key parameter to template the Au NPs on the spherulite surfaces. The preparation processes and the key factors leading to the formation of PA66 spherulites coated with Au NPs are discussed. Moreover, the efficiency of the coated spherulites as a potential catalyst is proved by demonstrating the reduction of methylene blue via UV-visible spectrometry.