  Membranes are ubiquitous in nature with primary functions that include
adaptive filtering and selective transport of chemical and molecular species.
Being critical to cellular functions, they are also fundamental in many areas
of science and technology. Of particular importance are the adaptive and
programmable membranes that can change their permeability or selectivity
depending on the environment. Here, we explore implementation of such
biological functions in artificial membranes and demonstrate two dimensional
self assembled heterostructures of graphene oxide and polyamine macromolecules,
forming a network of ionic channels that exhibit regulated permeability of
water and monovalent ions. This permeability can be tuned by a change of pH or
the presence of certain ions. Unlike traditional membranes, the regulation
mechanism reported here relies on specific interactions between the membranes
internal components and ions. This allows fabrication of membranes with
programmable, predetermined permeability and selectivity, governed by the
choice of components, their conformation and their charging state.
