Gold nano-ripple structure with potential for bio molecular sensing applications

Abstract

We introduce a simple and cost-effective scheme for bio-sensing using nano-ripple structures. One dimensional metallic nano-ripple structures formed by gas cluster ion beam irradiation have shown polarization of light as well as localized surface plasmon resonance. These localized surface plasmon resonance based bio sensors not only are capable of label free real time analytical detection but also show high sensitivity. The nano-surface morphology determines the changes in the plasmonic properties of nano-structures hence the plasmonic response is tunable. By adsorbing a mono-layer of thiolated organic compound on the surface of these substrates we identified the shift in the localized surface plasmon resonance peaks triggered by the change of dielectric function in the neighborhood of the structures. These plasmonic nano-metallic structures can be utilized to observe the change of localized surface plasmon resonance frequency due to the cycle of adsorption, re-adsorption and reactions taking place on the surface that can potentially be mapped in to reaction mechanics. The bio-sensor has monolayer molecule-coating sensitivity and specific selectivity. This study can be extended to sensing biological molecules such as proteins, DNAs, antibodies and antigens.