Holes in Gold Enhance Molecular Sensing
News May 19, 2015
Non-metallic mesoporous structures have already demonstrated potential for applications in gas storage, separation, catalysis, ion-exchange, sensing, polymerization and drug delivery. Metal mesoporous films could have fascinating and useful optical properties as they are effectively the inverse of nanoparticle arrays. Now for the first time a collaboration of researchers in Japan, Turkey, Korea and Sweden demonstrate a simple approach for producing metal films with regular tuneable mesopores, and show their potential for high-sensitivity optical detection.
When light is incident on nanostructures of noble metals such as gold, the electrons oscillate collectively – a so-called plasmon – and this greatly enhances the electromagnetic field close by. According to Babinet’s principle in optics, the inverse structure – a mesoporous film – should lead to similar local electromagnetic field enhancements, but as Yamauchi and his colleagues point out in their report, controlling gold crystal growth well enough to produce mesoporous films has so far been difficult.
The success of their approach relies on electrochemistry and micelle self-assembly. They dissolve hydrogen gold chloride (or chloroauric acid, HAuCl4) and polystyrene-block¬-poly(oxyethylene) in a solution of tetrahydrofuran, which leads to the formation of micelles with a polystyrene core and polyoxyethylene shell. The micelles reduce the AuCl4- ions so that gold deposits on the micelles. The result is highly regular gold mesopores with a size that can be tuned by varying the concentrations of the HAuCl4 and polystyrene-block¬-poly(oxyethylene).
Calculations showed that hotspots of high electric field enhancement indeed exist in the pores of the structure, and the plasmon resonances can be tuned by changing the pore size. Further experiments confirmed the surface enhancement of protein spectral signatures, known as surface enhanced Raman scattering. The researchers conclude, “The electrochemical approach is widely applicable to embed uniform mesopores in other metal and alloy systems, which are generally difficult to be synthesized.”
Rechargable Antibacterial Coating - Just Add Bleach!News
Stainless steel is the gold standard for kitchen appliances and cookware, described as modern and sleek. But bacteria can grow on stainless steel surfaces, contaminating food. Current coatings available on the market are pricey and potentially harmful, so scientists have now developed an affordable specialized polymer coating for such surfaces that they can recharge with bleach treatments.READ MORE
Low Temperatures Turn Stem Cells into Calorie-Burning FatNews
The secret to healthy eating may not be in freezer food, but low temperatures can help turn stem cells into brown fat, a type of fat which helps burn calories. A new study could turn this knowledge into weight-loss treatments.READ MORE
Comments | 0 ADD COMMENT
11th International Conference and Exhibition on Metabolomics & Systems Biology
May 17 - May 19, 2018