Title

Adsorption of Diblock Polypeptides on Polystyrene Latex

Abstract

The adsorption of peptides at solid/liquid interfaces is affected by peptide/surface and peptide/peptide hydrophobic and electrostatic forces. Three diblock copolypeptides and two homopeptides were adsorbed on poly(styrene) nanospheres from water, water/methanol, and water/glycerol mixtures at different pH's to study both of these effects. Peptides with one hydrophilic (glutamic acid or lysine) and one nonpolar block (alanine) or with both hydrophilic blocks with opposite charges (glutamic acid and lysine) were chemically synthesized and used as adsorbates in this study. The amount adsorbed was determined, and dynamic light scattering (DLS) was used to measure the adsorbed layer thickness. It was found that peptide/surface and peptide/peptide electrostatic interactions dominate the adsorption process. Hydrophobic forces also play a role, but secondary to electrostatic forces. Positively charged blocks show high affinity for the surface, whereas negatively charged blocks were excluded from it. Poly(Lys) has the highest affinity by the surface, while (Glu)14-b-(Ala)5 has the lowest. Adsorption of all peptides was inhibited by methanol and promoted by glycerol. The adsorption for (Lys)5-b-(Glu)6 was extremely sensitive to pH, irrespective of cosolvent, whereas the thickness for (Lys)30-b-(Ala)41 was sensitive to pH as well as cosolvent. Aggregation was observed in the presence of the nanosurfaces but not in the bulk peptides under some pH and solvent conditions.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Adsorbed Layers; Adsorption Process; Copolypeptides; Cosolvents; Diblocks; Glutamic Acid; High Affinity; Homopeptides; Hydrophilic Blocks; Hydrophobic Forces; Nanosurfaces; Non-Polar; Opposite Charge; Polystyrene Latexes; Positively Charged; Solid/Liquid Interfaces; Solvent Conditions; Water/Glycerol Mixtures; Amino Acids; Dynamic Light Scattering; Electrostatic Devices; Electrostatic Force; Glycerol; Hydrophilicity; Hydrophobicity; Methanol; Peptides; pH Effects; Polystyrenes; Styrene; Adsorption; Latex; Polystyrene Derivative; Chemical Phenomena; Chemistry; Isoelectric Point; Hydrophobic and Hydrophilic Interactions; Solvents

International Standard Serial Number (ISSN)

0743-7463; 1520-5827

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 American Chemical Society (ACS), All rights reserved.

PubMed ID

23009064

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