Tuesday, December 30, 2008

More Nanoparticle Bondage

In a previous entry, I mentioned a technique whereby gold nanoparticles could be attached to the exterior of fungal cells to form unusual hybrid materials. Once the gold scaffolding was complete, the fungi could be removed (digested), leaving behind 3 dimensional gold structures. This started me thinking that there might be a rich field of exploration here, finding simple ways of attaching metal nanoparticles like gold to new substrates in the hopes of creating new 3-dimensional structures with unusual properties. Even better, many of these techniques would be based on aqueous chemistry, which make them especially appealing (to me at least).

Of course, within a week or two of that article, two more articles appeared which demonstrated that other research groups are already way ahead of me in this area.

In the first paper, J. P. Hinestroza and coauthors at Cornell University (Ithaca, NY) and the University of California, Davis, described a method of applying silver nanoparticles to porous nylon fibers, resulting in fibers with strong antibacterial properties. By using AQUEOUS chemistry techniques (pH control, isoelectric points, citrate stabilization, etc.), they found they could control the resulting properties of the final material. When you consider the fact that the original gold and silver nanoparticles can be easily produced by reducing aqueous solutions of the metal salts, you begin to realize just how much fun this type of project could be for an aqueous inorganic chemist like myself.

In the second paper, Y. Yin and co-workers at the University of California, Riverside, described the synthesis of gold nanoparticle catalysts supported on silica-encapsulated Fe3O4 spheres and protected by a porous silica shell. The purpose of the silica shell was to fix the gold nanoparticles in place for catalysis. Apparently the resulting material were found to be a good catalyst for the liquid-phase reduction of 4-nitrophenol with NaBH4. Interestingly, the purpose of placing the catalyst onto Fe3O4 cores was to give the researchers a convenient way of separating the catalyst from the reaction mixture. Nice.

I'm predicting a whole slew of papers are going to start appearing which involve placing gold and silver nanoparticles on every material imaginable.

Of course, maybe that's already happened and I just haven't noticed yet.

Ah yes..., it feels good to be blogging again.

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