Pentafluorophenyl-based single-chain polymer nanoparticles as a versatile platform towards protein mimicry

Proteins are biopolymers folded into 3D-structures and are omnipresent in biological systems, where they fulfil a wide array of complex functions. Mimicking the exceptional characteristics of proteins with synthetic analogues may likewise give unprecedented control over a nanomaterial's pharmacokinetic behaviour, enabling controlled delivery of therapeutics or imaging agents. Recent advances in polymer science have enabled the formation of bio-inspired single-chain polymer nanoparticles (SCNPs), which are formed by intramolecular collapse of individual polymer chains, and display sizes ranging from 5-20 nm. Here, we describe the preparation of SCNPs containing activated ester moieties, facilitating SCNP functionalization without altering its backbone structure. Pentafluorophenyl-functional SCNPs were prepared through intramolecular thiol-Michael addition crosslinking of thiol-functional precursor copolymers. Post-formation functionalization of the resulting SCNPs through substitution of the activated pentafluorophenyl esters with a variety of amines resulted in a series of water-soluble SCNPs with fluorescent labels, 'click' functionality, amino acids and even peptides. This synthetic strategy offers a straightforward method towards SCNP modification and SCNP-protein hybrids, giving access to easily adjustable physicochemical properties and protein mimicry.