Quaternary Amine-Terminated Quantum Dots Induce Structural Changes to Supported Lipid Bilayers.

Area of Science:

• Biophysics
• Materials Science
• Cell Biology

Background:

• The cytoplasmic membrane is a vital barrier for cells.
• Nanomaterial interactions can compromise membrane integrity, leading to adverse effects.
• Supported lipid bilayers serve as experimental models for cellular membranes.

Purpose of the Study:

• To investigate the impact of quantum dots functionalized with poly(diallyldimethylammonium chloride) (PDDA) on supported lipid bilayer structure.
• To understand how nanomaterial surface charge and functionalization affect membrane organization.

Main Methods:

• Utilized quartz crystal microbalance with dissipation monitoring (QCM-D) to analyze membrane-surface interactions.
• Employed real-time atomic force microscopy (AFM) to visualize structural changes in lipid bilayers.
• Investigated interactions with zwitterionic lipid bilayers in liquid-disordered and liquid-ordered phases.

Main Results:

• Positively charged quantum dots functionalized with PDDA attach to and induce rearrangements in zwitterionic lipid bilayers.
• PDDA-coated quantum dots and PDDA caused the disappearance of liquid-ordered domains in lipid bilayers.
• Observed structural changes occurred in both single-phase and phase-segregated lipid bilayers.

Conclusions:

• PDDA-coated quantum dots destabilize membrane domains, likely due to increased surface energy from nanoparticle collisions.
• Nanomaterial-induced alterations in membrane structure can have significant biological implications.
• Findings provide insights into the mechanisms of nanomaterial-cell membrane interactions.