May 16, 2014
Nanorod arrays enhance amino acid separation signal
As the miniaturization of microfluidic devices continues, the sample testing volume required reduces but the need for signal enhancement increases. Existing technologies already demonstrate the difficulty of decorating a microfluidic channel with this required signal enhancing function. Reporting in Nanotechnology, researchers at the Hong Kong Baptist University and The Hong Kong University of Science and Technology may have overcome this.
The researchers show that Ag nanorod (ND) arrays – when directly integrated into a microfluidic channel by oblique angle deposition (OAD) – show great enhancement in the capillary electrophoretic (CE) separation signal of amino acids.
Enhancing the signal
The authors take advantage of OAD to integrate a multilayer of SiO2 NDs/Ag NDs with a CE microdevice. The amino acids, Arg and Gly, labelled with fluorescent molecules emit an enhanced signal when they are passing through the Ag NDs deposited on the microchannel bottom: a result of the localized surface plasmon resonance. The enhancement is 6.5-fold when the channel depth is 10 µm. The SiO2 ND underlayer isolates the Ag NDs and effectively suppresses the oxidation of Ag during the electrophoretic process.
More and more studies report that metal NDs show a much higher fluorescence-enhancing ability than the traditional metal nanospheres. This report is the first that achieves a metal-enhanced fluorescence signal in a microfluidic system by immobilizing Ag NDs onto a microchannel bottom. The researchers believe that Ag NDs could facilitate the CE separation signal more by further reducing the channel dimensions.
More information about the research can be found in the journal Nanotechnology 25 225502.
About the author
Junxue Fu works at the Hong Kong Baptist University in Hong Kong. With a background in physics, her current research interests include nanostructure fabrication, localized surface plasmon resonance of metal nanostructures, biosensors, biomanipulation and microfluidics.