Probing the Influence of Hydrophobicity of Modified Gold Nanoparticles in Modulating the Lipid Surface Behavior Using...

Area of Science:

• Surface Science
• Nanotechnology
• Biophysics

Background:

• Understanding nanoparticle-cell membrane interactions is crucial for biomedical applications.
• Nanoparticle hydrophobicity significantly influences these interactions, primarily through hydrophobic forces.
• Thiol-capped gold nanoparticles (GNPs) offer a tunable platform to study hydrophobicity effects.

Purpose of the Study:

• To investigate how the hydrophobic alkyl chain length of thiol-capped GNPs affects lipid monolayers.
• To elucidate the impact of varying GNP hydrophobicity on membrane structure and interfacial water.
• To provide insights for optimizing nanoparticle design in drug delivery and lipid-based systems.

Main Methods:

• Utilized vibrational sum frequency generation (VSFS) spectroscopy to probe molecular interactions.
• Employed a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipid monolayer as a model cell membrane.
• Studied GNPs functionalized with varying thiol chain lengths (heptanethiol C7 to octadecanethiol C18) and used deuterated lipids for control experiments.

Main Results:

• Short alkyl chains (C7) on GNPs induced minimal changes in the lipid monolayer's C-H vibrations.
• Increasing alkyl chain length (C10-C12) led to enhanced hydrophobic interactions, increasing the lipid monolayer's orientational order.
• Long alkyl chains (C18) caused significant perturbations and disordering of the lipid monolayer, also affecting interfacial water structure.

Conclusions:

• The hydrophobic nature and alkyl chain length of GNPs critically influence lipid monolayer structure and dynamics.
• Specific chain lengths induce distinct effects, ranging from minimal perturbation to significant structural disordering.
• These findings are vital for designing effective nanoparticle-based drug delivery systems and stable lipid formulations.