Adsorption of Diblock Polypeptides on Polystyrene Latex
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.
R. Jain and D. Forciniti, "Adsorption of Diblock Polypeptides on Polystyrene Latex," Langmuir, vol. 28, no. 43, pp. 15323-15335, American Chemical Society (ACS), Oct 2012.
The definitive version is available at https://doi.org/10.1021/la302380z
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)
Article - Journal
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