Surface-enhanced Raman scattering investigation of nucleobases adsorbed on samples of Martian analogue material

The identification of two nucleobases (adenine and hypoxanthine) by Surface-Enhanced Raman Scattering (SERS) on different mineral substrates was adopted as a test case to verify the capability of this analytical technique to detect trace amounts of organic or biological substances deposited over, or contained in, Martian regolith. Raman spectra were collected on polished samples of calcite, dolomite, magnesite, siderite, anhydrite, and gypsum, onto which traces of nucleobases were added. While spectroscopic features of the two nucleobases could not be observed in normal Raman spectrum, the addition of silver nanoparticles allowed easy identification of the vibrational bands characteristic of the two nucleobases.