Molecular mechanisms of pH-tunable stability and surface coverage of polypeptide films

Adam L. Harmat, Maria Morga, Jodie L. Lutkenhaus, Piotr Batys*, Maria Sammalkorpi

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
64 Downloads (Pure)

Abstract

Streaming potential and quartz crystal microbalance measurements, combined with all-atom molecular dynamics simulations, were used to study the pH dependency of the adsorption of two basic homopolypeptides, poly-L-lysine (PLL) and poly-L-arginine (PARG), on α-quartz surface. We report that the observed adsorption behavior rises from an interplay of i) the change in the number of possible peptide-surface ion pairs between the charged moieties and ii) repulsive electrostatic interactions between the polypeptide molecules. For low pH values, polypeptide adsorption was strongest and stable monolayers were formed. However, electrostatic repulsion between the polypeptides led to a relatively low maximum surface coverage. On the other hand, higher pH led to more weakly bound, but significantly denser, peptide films with limited stability. Simulations indicate that electrostatic interactions are the main driving force for adsorption, while hydrogen bonding and non-specific interactions also contribute. Additionally, the important role of the counterions of the negatively charged quartz surface that form a positively charged ion adlayer is highlighted. Ion release of the condensed sodium ions at the charged surface occurs via displacement by polypeptide adsorption. The mechanisms revealed by this work provide systematic guidelines to engineering active surfaces of charged peptides with controlled surface coverage and reversible binding.

Original languageEnglish
Article number156331
Number of pages12
JournalApplied Surface Science
Volume615
Early online date12 Jan 2023
DOIs
Publication statusPublished - 1 Apr 2023
MoE publication typeA1 Journal article-refereed

Keywords

  • Adsorption mechanism
  • Electrostatic interactions
  • Hydrogen bonding
  • Poly-L-arginine
  • Poly-L-lysine
  • α-quartz

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