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Molecular Sponge: pH-Driven Reversible Squeezing of Stimuli-Sensitive Peptide Monolayers
Grazia M L Messina1, Benedetta Di Napoli2, Marta De Zotti3
1Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemical Sciences , University of Catania and CSGI , Viale Andrea Doria 6 , 95125 Catania , Italy.
Langmuir : the ACS Journal of Surfaces and Colloids
|March 14, 2019
Summary
This study reveals that peptide monolayers with lysine (Lys) residues change structure with pH. This pH-induced wetting/dewetting process alters peptide aggregation, offering insights into stimuli-responsive systems.
Area of Science:
- Biomaterials Science
- Surface Chemistry
- Peptide Science
Background:
- Stimuli-responsive materials are crucial for advanced applications.
- Understanding peptide behavior at interfaces is key to designing responsive systems.
- Lysine residues can significantly influence peptide properties in response to environmental changes.
Purpose of the Study:
- To investigate the pH-dependent structural changes of peptide monolayers.
- To elucidate the mechanism behind the stimuli-responsive behavior of a specific peptide analogue.
- To explore the role of lysine residues in mediating pH-induced conformational changes.
Main Methods:
- Quartz crystal microbalance with dissipation monitoring (QCM-D)
- Surface plasmon resonance (SPR)
- Nanoplasmonic sensing
- Fourier transform infrared-reflection-attenuated spectroscopy (FTIR-RAS)
- Dynamic force spectroscopy (DFS)
- Molecular dynamics (MD) simulations
Main Results:
- Chemisorbed monolayers of a lysine-containing peptide analogue (L1) exhibited cyclic changes in structure, thickness, and density upon pH switching (acidic to basic).
- A homologous peptide lacking lysine residues showed no response to pH changes, highlighting the critical role of lysine.
- The observed behavior was attributed to a pH-induced wetting/dewetting process driven by the transition of charged lysine groups to uncharged ones, altering hydrophilicity and promoting collective changes in peptide aggregation state.
Conclusions:
- Lysine residues are essential for the pH-responsive behavior of the studied peptide monolayers.
- The pH-induced wetting/dewetting mechanism involving lysine protonation/deprotonation governs the structural and aggregation state changes.
- These findings provide a foundation for re-examining the mechanisms of various stimuli-responsive systems.
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