UV-induced modification of graphene-based sensor surfaces investigated by Raman microscopy mapping

We investigate the effects of UV irradiation on novel nanomaterial-based surfaces containing graphene nanoplatelets (GNPs) and DNA, which were designed for radiation sensing applications. Multifunctional surfaces were realized by combining the good electrical conductivity of GNPs with the biocompatibility and UV sensitivity of double-stranded DNA. The GNP/DNA nanomaterial was assembled by sonication in aqueous solution, dispersed into a PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)) matrix to improve its stability and electrical conductivity, and then applied as a coating onto suitable substrates. The UV-sensitivity of the GNP/DNA/PEDOT:PSS samples was investigated, before and after exposure to the more energetic UV-C band, using surface analytical techniques, SEM imaging and electrical impedance spectroscopy. In particular, Raman microscopy mapping proved to be useful to investigate the physico-chemical properties of the sensor surfaces and their modifications upon UV irradiation. This technique allowed to detect the different chemical changes generated by the interaction of UV-C with each component of the nanocomposite film. Results give information about the potential applications of the GNP/DNA/PEDOT:PSS surfaces in radiation monitoring devices to be used in industrially-relevant environments (e.g. sterilization processes) or in space environment where the UV-C radiation band is not screened by the atmosphere.