DPPTE Thiolipid Self-Assembled Monolayer: A Critical Assay.

Area of Science:

• Materials Science
• Surface Chemistry
• Biophysics

Background:

• Supported lipid membranes mimic biological interfaces for biotechnological applications.
• Phospholipid self-assembled monolayers (SAMs) on gold are widely studied but present characterization challenges.
• Discordant data exist regarding the formation and properties of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) SAMs.

Purpose of the Study:

• To characterize DPPTE SAMs on gold surfaces.
• To investigate the molecular density, thickness, capacitance, and morphology of DPPTE SAMs.
• To rationalize previously reported discordant experimental data on DPPTE SAMs.

Main Methods:

• Cyclic voltammetry blocking experiments for SAM formation verification.
• Reductive desorption measurements for molecular density estimation.
• Quartz crystal microbalance, ellipsometry, impedance spectroscopy, and atomic force microscopy for film characterization.
• Monte Carlo simulations for molecular-level morphological insights.

Main Results:

• DPPTE molecules incubated below their phase transition temperature form SAMs on gold.
• These SAMs exhibit domain structures of varying order, a novel observation.
• Experimental data were rationalized, providing a clearer understanding of DPPTE SAM formation.

Conclusions:

• DPPTE can form ordered phospholipid SAMs on gold surfaces with distinct domain structures.
• This study resolves inconsistencies in prior research on DPPTE SAMs.
• The findings offer new molecular insights into phospholipid SAM formation on gold.