Title: Protein extraction into the bicontinuous microemulsion phase of a Water/SDS/pentanol/dodecane winsor-III system: Effect on nanostructure and protein conformation

Abstract

Bicontinuous microemulsions (BμEs), consisting of water and oil nanodomains separated by surfactant monolayers of near-zero curvature, are potentially valuable systems for purification and delivery of biomolecules, for hosting multiphasic biochemical reactions, and as templating media for preparing nanomaterials. We formed Winsor-III systems by mixing aqueous protein and sodium dodecyl sulfate (SDS) solutions with dodecane and 1-pentanol (cosurfactant) to efficiently extract proteins into the middle (BμE) phase. Bovine serum albumin (BSA) and cytochrome c partitioned to the BμE phase at 64% and 81% efficiency, respectively, producing highly concentrated protein solutions (32 and 44 g L^–1, respectively), through release of water and oil from the BμEs. Circular dichroism spectroscopic analysis demonstrated that BSA underwent minor secondary structural changes upon incorporation into BμEs, while the secondary structure of cytochrome c and pepsin underwent major changes. Small-angle x-ray scattering (SAXS) results show that proteins promoted an increase of the interfacial fluidity and surface area per volume for the BμE surfactant monolayers, and that each protein uniquely altered self-assembly in the Winsor-III systems. Cytochrome c partitioned via electrostatic attractions between SDS and the protein’s positively-charged groups, residing near the surfactant head groups of BμE monolayers, where it decreased surfactant packing efficiency. BSA partitioned through formationmore » of SDS-BSA complexes via hydrophobic and electrostatic attractive interactions. As the BSA-SDS ratio increased, complexes’ partitioning favored BμEs over the oil excess phase due to the increased hydrophilicity of the complexes. In conclusion, this study demonstrates the potential utility of BμEs to purify proteins and prepare nanostructured fluids possessing high protein concentration.« less

Authors:

Hayes, Douglas G. ^[1]; Ye, Ran ^[1]; Dunlap, Rachel N. ^[2]; Cuneo, Matthew J.  ^[3];

• Search DOE PAGES for author "Cuneo, Matthew J."
• Search DOE PAGES for ORCID "0000-0002-1475-6656"

Pingali, Sai Venkatesh  ^[3];

• Search DOE PAGES for author "Pingali, Sai Venkatesh"
• Search DOE PAGES for ORCID "0000-0001-7961-4176"

O’Neill, Hugh M.  ^[3];

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• Search DOE PAGES for ORCID "0000-0003-2966-5527"

Urban, Volker S.  ^[3]

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• Search DOE PAGES for ORCID "0000-0002-7962-3408"

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+ Show Author Affiliations

1. Univ. of Tennessee, Knoxville, TN (United States)
2. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Thu Sep 07 00:00:00 EDT 2017

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1413609

Alternate Identifier(s):

OSTI ID: 1549795

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Colloids and Surfaces. B, Biointerfaces

Additional Journal Information:

Journal Volume: 160; Journal Issue: C; Journal ID: ISSN 0927-7765

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Bicontinuous microemulsions; Bovine serum albumin; Cytochrome c; Protein extraction; Protein-surfactant interactions; Sodium dodecyl sulfate; Small-angle neutron scattering (SANS); Small-angle x-ray scattering (SAXS); Winsor-III microemulsion systems; Pepsin