  Graphene conductive properties have been long exploited in the field of
organic photovoltaics and optoelectronics by the scientific community
worldwide. We engineered and characterized a hybrid biointerface in which
graphene is coupled with photosensitive polymers, and tested its ability to
elicit lighttriggered neural activity modulation in primary neurons and blind
retina explants. We designed such a graphene-based device by modifying a
photoactive P3HT-based retinal interface, previously reported to rescue light
sensitivity in blind rodents, with a CVD graphene layer replacing the
conductive PEDOT:PSS layer to enhance charge separation. The new graphene-based
device was characterized for its electrochemical features and for the ability
to photostimulate primary neurons and blind retina explants, while preserving
biocompatibility. Light-triggered responses, recorded by patch-clamp in vitro
or MEA ex vivo, show a stronger light-transduction efficiency when the neurons
are interfaced with the graphene-based device with respect to the
PEDOT:PSS-based one. The possibility to ameliorate flexible photo-stimulating
devices via the insertion of graphene, paves the way for potential biomedical
applications of graphenebased neuronal interfaces in the context of retinal
implants.
