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Stimuli-responsive nanoparticles are the focus of much current research, and what could be better than a nanoparticle that responds to one stimulus?  A nanoparticle which responds to two or three.

Xianmao Lu and his team have coupled plasmonic silver nanoparticles to magnetic iron oxide nanoparticles and wrapped both in a thermoresponsive polymer – poly(n-isopropylacrylamide).

When illuminated by sunlight the silver nanoparticles absorb the light and convert it to heat.  The increase in temperature causes the polymer wrapping to collapse and reduces steric repulsion between the nanoparticle dimers leading to clustering.

Sunlight induced clustering of Magnetic-Plasmonic Heterodimers.

This clustering enhances the magnetic separation of the very small dimers from the solution (the nanoparticles are less than 9 nm each).  When you’ve caught the nanoparticles and are done with them, you can turn the lights off and they will re-disperse.

Don’t worry if you live in a cloudy part of the world, you can use a solar simulator to induce the clustering.  It would probably be easier to turn off than the sun, too.

To read the details, check out this HOT Chem Comm article in full:
Thermoresponsive Nanoparticles + Plasmonic Nanoparticles = Photoresponsive Heterodimers: Facile Synthesis and Sunlight-Induced Reversible Clustering
Hui Han, Jim Yang Lee and Xianmao Lu
Chem. Commun., 2013, 49, Accepted Manuscript
DOI: 10.1039/C3CC42273A

Written by Geoff Nelson, web writer.

Nanocups of anatase TiO2 coated with Au nanoparticles are efficient photocatalysts, as reported in a recent ChemComm article by Chemical Science and Chem Soc Rev Advisory Board member Jinlong Gong and  his group at Tianjin University, China.

This new shape promises to increase reactive surface area by exposing the normally inaccessible surface of hollow spheres.  Compared to TiO2 hollow spheres, TiO2 nanocup particles increase the rate of the photocatalytic degradation of methylene blue in the visible light region by 46%.

This performance and the ease of nanocup synthesis are reasons to promote further research.  Thus, we may expect nanocups made from other metal oxides and inorganic materials to be incorporated into solar, photochemical, and catalytic applications in the future.

In addition, the ability of nanocups to confine small amounts of reactants may find utility in nanofluidic devices.

Gong et al.’s work has recently been highlighted as part of a C&EN article on novel nanostructures.

Read this ChemComm article in full:

Mesoporous anatase TiO₂ nanocups with plasmonic metal decoration for highly active visible-light photocatalysis

Jianwei Lu, Peng Zhang, Ang Li, Fengli Su, Tuo Wang, Yuan Liu and Jinlong Gong
Chem. Commun., 2013, Advance Article
DOI: 10.1039/C3CC42029A

Geoff Nelson is a guest web-writer for ChemComm.  He currently works as a post-doctoral research associate in Dr David Payne’s research group in the Department of Materials at Imperial College, London.  Geoff’s current research concerns the synthesis and characterization of post-transition metal oxides for use in the energy sector.  His other research interests include carbon-based materials, biophysical chemistry, and surface science.