Adsorbed alpha-helical diblock copolypeptides: molecular organization, structural properties, and interactions

Area of Science:

• Surface science
• Biomaterials engineering
• Nanotechnology

Background:

• Self-assembled monolayers (SAMs) are crucial for surface functionalization.
• Polypeptides offer tunable properties for biomaterial applications.
• Understanding interfacial phenomena is key for nanoparticle ligand design.

Purpose of the Study:

• To develop and characterize 11-mercaptoundecanoic acid (MUA)-polypeptide bilayers.
• To model interactions between poly(diethylene glycol-l-lysine)-poly(l-lysine) (PEGLL-PLL) and nanoparticle ligand moieties.
• To elucidate polypeptide conformation, organization, and film properties.

Main Methods:

• Fabrication of PEGLL-PLL/MUA bilayers on gold substrates.
• Surface characterization using grazing-incidence IR spectroscopy, ellipsometry, and contact angle measurements.
• Analysis of polypeptide packing, graft density, and conformation as a function of molecular architecture.

Main Results:

• Adsorption is driven by electrostatic interactions and hydrogen bonding between PEGLL-PLL and MUA.
• The PLL block adopts a random-coil conformation, while the PEGLL block forms an alpha-helix.
• Film properties like graft density and molecular orientation depend on PEGLL-PLL architecture.
• The developed bilayers exhibit excellent stability over two weeks.

Conclusions:

• PEGLL-PLL/MUA bilayers serve as effective model systems for interfacial studies.
• Polypeptide conformation and surface organization are influenced by molecular design.
• The findings provide insights into designing functionalized surfaces for nanoparticle applications.