Assessing the Charge Transfer at the Cytochrome <i>c</i><sub>553</sub>/Graphene Interface: A Multiscale Investigation

The creation of bio-organic interfaces, in which proteins play an active role in the transfer of charges, is becoming more and more important, considering the almost endless combinations of protein–metal interfaces and their potential use in biosensors and solar-to-fuel devices. In this work, we present a new interface consisting of cytochrome and graphene, in which the protein with its heme group plays a key role in the transport of charges to the metal. By means of multiscale computational simulations, we found four thermodynamically stable conformations of the protein on the graphene surface, and with in-depth <i>ab initio</i> calculations, we observed that the effective transfer of charge from graphene to the heme group strongly depends not only on the position of the group but also on its relative orientation with respect to graphene. A model porphyrin–graphene interface confirmed the interplay between orientation and position in the strength of the transfer of charges at the interface.