Functional nanocomposites based on graphene/DNA interface: Towards a bio-inspired sensing of UV radiation effects

Ultraviolet (UV) radiation naturally characterizes the Earth environment and the outer space, representing one of the most hazardous agents for human health and for the useful lifetime of organic materials. The possibility to develop a UV-detecting system able to ensure a good sensitivity and stability during measurements, and possessing at the same time low weight and real-time response, represents a fascinating challenge towards new technological advances in the field of radiation sensitive materials. This thesis is focused on the design, preparation and testing of bio-inspired UV sensitive nanocomposites based on graphene/DNA interface. The sensing principle of such nanocomposites relies on the highly conductive nature of graphene combined with the chemical sensitivity of DNA strands to UV radiation, particularly in the UV-C band (100 nm to 280 nm). The engineering of these bio-hybrid nanomaterials in the form of thin films or miniaturized materials would be desirable to overcome traditional problems that affect space mission equipment, such as onboard encumbrance, or that can limit their use on terrestrial environments involving a daily use of UV radiation, such as sterilization plants. To this aim, the UV sensitive graphene/DNA filler was integrated in different polymer matrices based on poly(3,4-ethylenedioxythio-phene):poly(styrenesulfonate) (PEDOT:PSS) or polydimethylsiloxane (PDMS), obtaining stiff and flexible UV sensitive materials, respectively. The UV response was investigated using several techniques, including electrical impedance spectroscopy, Raman microscopy, optical contact angle, electrical tomography resistance. In addition, differential scanning calorimetry was used to analyze the curing behavior of the PDMS-based prepolymers and the thermal stability of the related nanocomposites. Results revealed that the bio-hybrid nanocomposites with graphene/DNA filler show a specific UV response, in particular in terms of electrical conductivity variations, and therefore these materials have the potential to be applied in UV monitoring systems, with the additional advantages of real-time response, low weight/mass and reduced size