Plasmonic Metasurface as Surface Enhanced InfraRed Absorption Spectroscopy Platform for Biosensing Applications

An innovative pixeled plasmonic metasurface (MS) has been developed for surface-enhanced infrared absorption (SEIRA) spectroscopy. The MS is comprised of different pixels, each designed to monitor a specific region of the electromagnetic spectrum. These pixels are engineered with plasmonic resonances that match the Amide I and Amide II vibrational bands in the range of 1500-2000 cm
^-1
. The proposed MS allowed a label-free spectroscopic characterization of a solution of biofibers isolated from cultured fibroblasts treated with an oligothiophene based oligomer. The reflection spectra acquired on areas containing a biofiber show the presence of the typical Amide I and Amide II vibrational bands, while reflection spectra acquired outside the fibers show no signal. Additionally, the evaluated enhancement factor (up to 1.4·10
³
) enables the detection of very small amounts of material bound on the proposed platform, as in the case of a biofiber placed on the nanoantennas composing the MS pixels.