NaCRe (Nature Inspired Circular Recycling) is a project that aims at developing recycling approaches for biological and soft matter that are inspired by the way Nature recycles proteins. We can first clarify that a protein is a sequence-defined polymer, that is a long macromolecule composed of a specific sequence of building blocks called amino acids. When a living being feeds it ingests a random mixture of proteins. Such a mixture is digested by decomposing the proteins back into their constituents, the amino acids, that are then used by the cell machinery to produce new proteins. It is important to notice that these initial mixtures is quite random (digestible proteins) and that the produced proteins are not related to the eaten ones. They are the proteins that the cell needs in that specific moment, furthermore the produced proteins are indistinguishable from any other protein, i.e. there is no loss of quality in the process.
Plastics are materials made of polymer, i.e. macromolecules composed of a series of monomers that repeat along a chain (or chain-like) backbone, thus proteins are a special type of polymers.
We can contrast Nature approach to protein recycling to our approach to recycling polymers, almost always we need to separate polymers depending on their chemical composition (we cannot afford a random mixture) and then we either produce again the starting materials (almost always at a loss of quality) or we produce a chemical substance to be re-used in creating other molecules(alas always the same).
NaCRe’s ambition is to reproduce Nature’s approach to recycling in laboratory settings, we plan to do so in (1) proteins, (2) DNA, and finally possibly also (3) in synthetic polymers. The first two goals have been fully met and a proof of principle for the third goal has also been performed.
In proteins the ambition is to start from a random mixture of proteins, especially focusing on proteins that are used as materials (e.g. silk) and to produce a new protein that has nothing to do with the initial one. The goals would be to produce a protein that itself can be used as a material. To achieve this goal the process must be efficient and scalable to quantities that allow for the building of a material whose properties can be tested. This goal has been fully met.
For DNA the goal is to show that a new this type of recycling can be performed with any sequence defined polymer. This has been proven and we have also shown that the resulting approach can be used to recycle spent PCR kits.
The final -very ambitious- goal was to try to produce a synthetic equivalent of protein and DNA. The true goal of NaCRe is to propose to the community a new approach to recycling that is inspired by Nature and has clear advantages relative to what we do currently. We have shown that there are approaches that can be used to recycle mixture of polymers suitably engineered.
