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Thermo-Responsive Surface Potential Modulation in Gold Nanoparticles Modified With Oligo(ethylene glycol) Derivatives
Hideyuki Mitomo1, Chie Takeuchi1, Mio Nakamura2
1Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 26, 2026
Summary
Temperature-responsive gold nanoparticles show tunable surface charge. Heating causes a hydrophilic-to-hydrophobic shift and increased negative potential by desorbing hydroxide ions, enabling controlled biological interactions.
Area of Science:
- Materials Science
- Nanotechnology
- Biomedical Engineering
Background:
- Smart materials respond to external stimuli, with temperature-responsive types crucial for biomedical applications.
- These materials typically switch between hydrophilic and hydrophobic states via hydration-dehydration transitions.
- The temperature-dependent surface charge behavior of such nanomaterials remains underexplored.
Purpose of the Study:
- To investigate the surface charge properties of temperature-responsive gold nanoparticles (AuNPs) coated with oligo(ethylene glycol) (OEG)-based ligands.
- To understand the relationship between temperature-induced phase transitions and surface potential changes.
- To explore the role of hydroxide ion adsorption/desorption in regulating nanoparticle interfacial properties.
Main Methods:
- Synthesized gold nanoparticles coated with OEG-based ligands.
- Measured zeta potential and surface potential as a function of temperature.
- Analyzed the correlation between ligand hydration state and surface charge.
Main Results:
- OEG-coated AuNPs exhibited negative zeta potentials near physiological pH.
- Increasing temperature induced a hydrophilic-to-hydrophobic transition.
- A simultaneous increase in negative surface potential was observed with heating, linked to hydroxide ion desorption.
Conclusions:
- Temperature-responsive nanomaterials can dynamically regulate surface charge.
- Hydroxide ion adsorption/desorption coupled with ligand dehydration influences interfacial properties.
- This provides a mechanism for stimulus-responsive control of nanomaterial interactions in biological systems.
