Atomic force microscopy observation of highly arrayed phospholipid bilayer vesicle on a gold surface

Area of Science:

• Surface science
• Nanotechnology
• Biomaterials

Background:

• Liposomes are crucial in drug delivery and biosensing.
• Controlling liposome morphology on electrode surfaces is vital for device performance.
• Atomic force microscopy (AFM) is a key technique for nanoscale surface analysis.

Purpose of the Study:

• To compare three distinct methods for immobilizing phospholipid vesicles (liposomes) onto gold surfaces.
• To investigate the morphological outcomes of different liposome preparation and immobilization techniques using tapping mode atomic force microscopy (TM-AFM).
• To assess the suitability of each method for creating uniform and stable electrode surfaces for potential biosensor applications.

Main Methods:

• Preparation of liposomes using extrusion with zwitterionic and anionic phospholipids.
• Immobilization of liposomes onto gold surfaces via amino coupling (L1-liposome).
• Direct immobilization using thiol-gold binding with 1-octadecanethiol (L2-liposome).
• Arrangement of liposomes using electron-beam (e-beam) lithography (L3-liposome).
• Morphological characterization using tapping mode atomic force microscopy (TM-AFM).

Main Results:

• The amino coupling method (L1-liposome) resulted in significant liposome aggregation and fusion.
• Direct attachment via thiol-gold binding (L2-liposome) yielded a uniform surface topology without aggregation.
• Electron-beam lithography (L3-liposome) demonstrated potential for controlled arrangement of individual liposomes.

Conclusions:

• Thiol-gold binding is an effective method for achieving uniform liposome immobilization on gold surfaces, avoiding aggregation.
• Electron-beam lithography presents a promising technique for precise liposome patterning on sensor surfaces.
• Optimized liposome immobilization is critical for advancing biosensor technology.