Volume 35, Issue 8 p. 1099-1105
Research Article

Hybrid phospholipid bilayer coatings for separations of cationic proteins in capillary zone electrophoresis

Elyssia S. Gallagher

Elyssia S. Gallagher

Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA

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Seid M. Adem

Seid M. Adem

Department of Chemistry, Washburn University, Topeka, KS, USA

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Leonard K. Bright

Leonard K. Bright

Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA

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Isen A. C. Calderon

Isen A. C. Calderon

Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA

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Elisabeth Mansfield

Elisabeth Mansfield

National Institute of Standards and Technology, Boulder, CO, USA

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Craig A. Aspinwall

Corresponding Author

Craig A. Aspinwall

Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA

BIO5 Institute, University of Arizona, Tucson, AZ, USA

Correspondence: Professor Craig A. Aspinwall, Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd, Tucson, AZ 85721, USA

E-mail:[email protected]

Fax: +1-520-621-8407

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First published: 23 January 2014
Citations: 11

Abstract

Protein separations in CZE suffer from nonspecific adsorption of analytes to the capillary surface. Semipermanent phospholipid bilayers have been used to minimize adsorption, but must be regenerated regularly to ensure reproducibility. We investigated the formation, characterization, and use of hybrid phospholipid bilayers (HPBs) as more stable biosurfactant capillary coatings for CZE protein separations. HPBs are formed by covalently modifying a support with a hydrophobic monolayer onto which a self-assembled lipid monolayer is deposited. Monolayers prepared in capillaries using 3-cyanopropyldimethylchlorosilane (CPDCS) or n-octyldimethylchlorosilane (ODCS) yielded hydrophobic surfaces with lowered surface free energies of 6.0 ± 0.3 or 0.2 ± 0.1 mJ m−2, respectively, compared to 17 ± 1 mJ m−2 for bare silica capillaries. HPBs were formed by subsequently fusing vesicles comprised of 1,2-dilauroyl-sn-glycero-3-phosphocholine or 1,2-dioleoyl-sn-glycero-3-phosphocholine to CPDCS- or ODCS-modified capillaries. The resultant HPB coatings shielded the capillary surface and yielded reduced electroosmotic mobility (1.3–1.9 × 10−4 cm2 V−1s−1) compared to CPDCS- and ODCS-modified or bare capillaries (3.6 ± 0.2 × 10−4 cm2 V−1s−1, 4.8 ± 0.4 × 10−4 cm2 V−1s−1, and 6.0 ± 0.2 × 10−4 cm2 V−1s−1, respectively), with increased stability compared to phospholipid bilayer coatings. HPB-coated capillaries yielded reproducible protein migration times (RSD ≤ 3.6%, n ≥ 6) with separation efficiencies as high as 200 000 plates/m.