Nanoantenna as a plasmonic molecular sensor with multi selective detection zones

Metallic nanostructures such as nanoantennas are capable of confining the energy of an incident radiation into volumes much smaller than the wavelength of incoming waves through localized surface plasmon resonance (LSPR). Here, we report on a strong enhancement of the vibrational signal from molecules adsorbed on metallic nanoantennas when those latter are excited at their LSPR frequencies. Because nanoantennas possess two plasmon modes with different directional profiles, it is likely possible to selectively probe the molecules adsorbed onto the nanoantenna side wall, on the nanoantenna top part or on the flat region of the substrate in-between antennas. This work gives promising perspectives to set-up a label-free vibrational biosensing platform with a multi-zones selectivity and a plasmon-enhanced sensitivity that could deserve diagnosis or surface molecular analysis.