Polymers are macromolecules comprising monomers linked in a chain. Nature makes extensive use of polymers with exquisitely defined monomer sequences for transmitting information (DNA, RNA) and for fabricating unique 3-D structures (peptides and proteins).
However, current processes for production of synthetic polymers with exactly defined sequences of monomers fall far short of Nature’s ideal. As yet, there are only limited successful reports describing synthesis of specific polymers, and so the potential benefits to society of defined monomer sequence polymers cannot be realised. Iterative synthesis, in which monomers are added one-at-a-time to the end of a growing polymer chain, affords exquisite control over the monomer sequence. However it requires separation of the growing polymer from the monomers with each and every cycle, which is the crucial, and hardest, step. To solve this problem, the EXACTYMER Advanced Grant works with attaching multiple growing polymer chains to a rigid hub, so that a macromolecular „nanostar“ is created which can be separated from reaction debris by membrane separation – we have named this „Nanostar Sieving“, and the defined monomer sequence exact polymers that are produced, „Exactymers“.
The objective of EXACTYMER is curiosity-driven, multidisciplinary research at the boundaries of membrane technology, polymer chemistry, and process engineering to create this new platform for exactymer synthesis using Nanostar Sieving. This technology can bring benefits to society through access to synthetic polymers of unprecedented accuracy. Potential applications for exactymers include medicine (where they could be used to conjugate drugs, and to link drugs to functional moieties such as affintiy ligands, cell penetrating agents, and imgaging agents), nanotechnology and information storage.
The overall objectives are:
Create ultra-selective, high permeance molecular separation membranes;
Expanding the chemistry of building blocks and iterative synthesis cycles for use in Nanostar Sieving
Integrate iterative chemistry and nanomembrane purification in the homostar nanofiltration platform for rapid, automated production of exactymers;
Exploring exactymer applications in healthcare, nanotechnology and information storage.
From the Exactymer AdG we conclude that (i) the speed and accuracy of membrane separations, that is the ability to separate different molecules present in solution, can be greatly increased through manipulation of the molecular architecture of the membrane separating layers; (ii) fouling at the surface of membranes can be greatly reduced by attachment of a flexible grafting layer to the membrane surface; (iii) membrane separation is massivley influenced by the concentration of molecules in the mixture to be separated; (iv) exact PEG polymers allow exact determination of the PEGylations sites in biopharmaceutical proteins; (v) single nanopores drilled into ultrathin polyamide films show great potential for reading the monomer sequence on synthetic polymers; (vi) novel electroactive polymers can be formed under mild conditions using organic electron acceptors.
