Planar bilayer membranes from photoactivable phospholipids.

Area of Science:

• Biophysical Chemistry
• Materials Science
• Membrane Biophysics

Background:

• Planar bilayer membranes are crucial models for cell membranes.
• Characterizing their stability and conductivity is essential for various applications.
• Photoactivable phospholipids offer a route to dynamically control membrane properties.

Purpose of the Study:

• To characterize planar bilayer membranes formed from photoactivable phospholipids using low-frequency voltammetry.
• To assess the impact of in situ photoactivation and photopolymerization on membrane conductivity, capacitance, and stability.
• To evaluate the functional integrity of ionophores and ion channels within photoactivated membranes.

Main Methods:

• Formation of planar bilayer membranes from photoactivable phospholipids.
• Cyclic voltammetry for simultaneous measurement of membrane conductivity and capacitance.
• In situ photoactivation using UV light (λ ≥ 320 nm).
• In situ photopolymerization of diene fatty acids.

Main Results:

• Photoactivation of C14-PED (head-group photosensitive phospholipid) did not alter membrane conductivity or capacitance.
• Ionophore (valinomycin) and ion channel (gramicidin) activities remained functional after C14-PED photoactivation.
• Photopolymerization of C16-DENPC (diene fatty acid phospholipid) led to short membrane lifetimes, increased conductivity, or rupture.

Conclusions:

• Head-group photosensitive phospholipids like C14-PED can form stable bilayer membranes with tunable properties.
• Photopolymerization of fatty acid chains can be used to modify membrane properties but may compromise stability.
• Voltammetric techniques are effective for characterizing photoactivable phospholipid membranes and their response to light stimuli.