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.

Nanorod advantages

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.

Further reading

A nanohole in one (July 2013)
Nanowire arrays separate proteins (Mar 2013)