J. Am. Chem. Soc. 136, 12888–12891 (2014)

The machinery of living organisms is founded on the ability of biomacromolecules to fold and coil. Recently, scientists have begun to explore the possibility of creating artificial systems from synthetic polymers that can fold in a predictable manner. Although nanoparticles have been created by folding linear polymers, it remains challenging to make polymer particles that are comprised of multiple, foldable domains. Raj Kumar Koy and Jean-François Lutz at the Institut Charles Sadron in Strasbourg have now synthesized polymer nanoparticles in which two polymer subdomains fold independently of each other.

The researchers start by devising a foldable single-chain polymeric sequence that contains two chemically distinct parts separated by a polystyrene spacer. Both chemically active sections contain variations of an N-substituted maleimide that can undergo intramolecular crosslinking, but in one of the two domains, the maleimide is initially protected by a triisopropylsilyl group. To synthesize the folded nanoparticle, the researchers first induce intramolecular crosslinking in one domain. They then deprotect the second domain, which allows it to undergo intramolecular crosslinking and form nanoparticles with two distinct subdomains.