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Title: Effect of Small Molecule Osmolytes on the Self-Assembly and Functionality of Globular Protein-Polymer Diblock Copolymers

Blending the small molecule osmolytes glycerol and trehalose with the model globular protein–polymer block copolymer mCherry-b-poly(N-isopropyl acrylamide) (mCherry-b-PNIPAM) is demonstrated to improve protein functionality in self-assembled nanostructures. The incorporation of either additive into block copolymers results in functionality retention in the solid state of 80 and 100% for PNIPAM volume fractions of 40 and 55%, respectively. This represents a large improvement over the 50–60% functionality observed in the absence of any additive. Furthermore, glycerol decreases the thermal stability of block copolymer films by 15–20 °C, while trehalose results in an improvement in the thermal stability by 15–20 °C. These results suggest that hydrogen bond replacement is responsible for the retention of protein function but suppression or enhancement of thermal motion based on the glass transition of the osmolyte primarily determines thermal stability. While both osmolytes are observed to have a disordering effect on the nanostructure morphology with increasing concentration, this effect is less pronounced in materials with a larger polymer volume fraction. Glycerol preferentially localizes in the protein domains and swells the nanostructures, inducing disordering or a change in morphology depending on the PNIPAM coil fraction. In contrast, trehalose is observed to macrophase separate from the block copolymer, which resultsmore » in nanodomains becoming more disordered without changing significantly in size.« less
Authors:
; ;  [1]
  1. MIT
Publication Date:
OSTI Identifier:
1095367
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biomacromolecules; Journal Volume: 14; Journal Issue: 9
Publisher:
American Chemical Society
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
DOE - BASIC ENERGY SCIENCESU.S. AIR FORCE- OFFICE OF SCIENTIFIC RESEARCH
Country of Publication:
United States
Language:
ENGLISH