Transport in nanopores and nanochannels: some fundamental challenges and nature-inspired solutions

The field of solid-state nanopores and nanochannels has grown exponentially in the past five years. Recent advances have greatly broadened the spectrum of available gating stimuli, expanded applications in sensing, energy conversion, and separation science, and improved our understanding of the mechanisms that govern ion transport in nanometer-sized channels and pores. Despite these impressive achievements, there still exists very challenging (and very exciting) research directions. This review focuses on three of these directions: i) ion selectivity: is it possible to construct channels that discriminate one type of ion from others with the same charge and similar size? ii) Integration with chemical networks: how can chemical networks, which are ubiquitous in living organisms, be integrated with pores and channels to enable new functions and enhance current applications? iii) Transport of cargoes larger than ions: is it possible to achieve selective and stimuli-gated transport of macromolecules and nanoparticles through synthetic pores? A brief analysis of biological channels and pores demonstrates that nature had evolved fascinating solutions for these three problems that may serve as a source of inspiration.