As for a possible suggestion for a routing method, flooding can be very efficient in such environment since the transmission range of the nodes is in the nano scale. and it is the easiest to study and implement for a first choice.
then you can search for possible implementations for routing purposes.
NOC routing protocols can also help in this field since the scale also in nano meters.
these are just some thoughts. But i would go for flooding first to study and see the environment behavior.