Abstract
Single-chain polymer nanoparticles (SCNPs) combine the chemical diversity of synthetic polymers with the intricate structure of biopolymers, generating versatile biomimetic materials. The mobility of polymer chain segments at length scales similar to secondary structural elements in proteins is critical to SCNP structure and thus function. However, the influence of noncovalent interactions used to form SCNPs (e.g., hydrogen-bonding and biomimetic secondary-like structure) on these conformational dynamics is challenging to quantitatively assess. To isolate the effects of noncovalent interactions on SCNP structure and conformational dynamics, we synthesized a series of amphiphilic copolymers containing dimethylacrylamide and monomers capable of forming these different interactions: (1) di(phenylalanine) acrylamide that forms intramolecular β-sheet-like cross-links, (2) phenylalanine acrylamide that forms hydrogen-bonds but lacks a defined local structure, and (3) benzyl acrylamide that has the lowest propensity for hydrogen-bonding. Each SCNP formed folded structures comparable to those of intrinsically disordered proteins, as observed by size exclusion chromatography and small angle neutron scattering. The dynamics of these polymers, as characterized by a combination of dynamic light scattering and neutron spin echo spectroscopy, was well described using the Zimm with internal friction (ZIF) model, highlighting the role of each noncovalent interaction to additively restrict the internal relaxations of SCNPs. These results demonstrate the utility of local scale interactions to control SCNP polymer dynamics, guiding the design of functional biomimetic materials with refined binding sites and tunable kinetics.
| Original language | English |
|---|---|
| Pages (from-to) | 889-895 |
| Number of pages | 7 |
| Journal | ACS Macro Letters |
| Volume | 13 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jul 16 2024 |
Funding
This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0021295. P.D.B. acknowledges support from the National Institute of General Medical Sciences of the National Institutes of Health under Award Number T32GM135122. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. We acknowledge the UNC Macromolecular Interactions Facility (CD and DLS; supported by the National Cancer Institute of the National Institutes of Health under award number P30CA016086) and the UNC NMR Core Laboratory (supported by the National Science Foundation Award Number CHE-1828183). Model protein SAXS and SANS data were acquired from the Small Angle Scattering Biological Data Bank. Finally, we thank Drs. Carrie Gao and Mary Odom for their assistance with SANS and NSE measurements, respectively.