Bioinspired control of protein transport through polymer functionalised nanopores

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This project will initiate a research programme in nanopore protein separation that is inspired by the nuclear pore complex (NPC). NPCs are complex, giant assemblies constituted from more than 400 proteins that define nanoscale pores (i.e. nanopores) ~40 nm in diameter. Each NPC spans the nuclear membrane which separates the cell nucleus and the rest of the cell. NPCs are the only conduits in and out of the cell nucleus in all eukaryotic cells and they allow only a small set of specific proteins and genetic material related to the functioning of the cell nucleus to pass through. All the other thousands of species of unrelated but similar molecules in the cell are rejected. Convenient separation of biomolecules is an enabling technology. NPC-studded nuclear membranes are effectively a highly specific and efficient molecular separation and purification membrane. They are capable of sorting through more than 1 kg of specific biomolecules in a human body per minute, far surpassing the performance of current technology. The creation of NPC-mimetic nanoporous membranes would benefit diverse biotechnology and biomedical applications, ranging from purification of protein disease markers for bedside medical diagnosis to continuous manufacturing of enzymes and protein therapeutics. Understanding the science underlying NPC function will help us achieve these applications and help us meet our 21st century challenges in healthcare and advanced manufacturing.The immediate goal of this project is to establish the design rules for enabling the basic function of the NPC - the sorting of proteins according to size using nanopores with a "virtual" size cut off and which, unlike current technology, are not clogged by random interactions with proteins. The pore size of the NPC is virtual because it has a physical diameter much larger than the size of the protein. A random protein cannot however pass through because each NPC nanopore is filled with a semi-porous polymer plug with an as yet unidentified structure that specifically repels proteins, except for those proteins specific to nuclear function. Biologists studying the NPC have proposed two leading theories to explain how the plug works: i) the "virtual gate" polymer brush model, and ii) the "selective phase" meshwork model. This project will create artificial nanopores that are decorated with synthetic polymers as simplified models to mimic these two theoretical structures. Experiments will be conducted to verify whether either of the theories is in fact feasible. The ultimate goal is to exploit these design rules for further development of the nanoporous membrane platform that incorporate increasingly advanced polymers for decorating the nanopores. This will create NPC-inspired nanoporous membranes with separation efficiency and selectivity that matches, and may eventually even surpass, native NPC function.