Capacitive and ionic currents in BLM from phosphatidic acid in Ca2+-induced phase transition.

Area of Science:

• Biophysics
• Membrane Biophysics
• Materials Science

Background:

• Bilayer lipid membranes (BLMs) are crucial models for cell membranes.
• Calcium ions (Ca2+) play significant roles in biological processes and membrane function.
• Understanding ion-induced membrane phase transitions is key to biomimetic technologies.

Purpose of the Study:

• To investigate the electrical current development over time in dipalmitoylphosphatidic acid BLMs upon Ca2+ introduction.
• To characterize the phase transition dynamics and associated electrical phenomena.
• To quantify charge transport and ionic channel properties.

Main Methods:

• Formation of dipalmitoylphosphatidic acid BLMs.
• Controlled introduction of Ca2+ ions to the surrounding medium.
• Monitoring of electric current development over time at constant temperature and pH.
• Analysis of capacitive current and single ionic channel conductivity.

Main Results:

• Observed phase transition in Ca2+-induced BLMs.
• Initial capacitive current followed by single ionic channel formation.
• Transported charge in capacitive current measured at 5 C/μF.
• Single ionic channel conductivity found to be in the range of 50–100 pSm.

Conclusions:

• Ca2+ ions induce a distinct phase transition in dipalmitoylphosphatidic acid BLMs.
• The transition involves capacitive current and subsequent ionic channel activity.
• The study provides quantitative data on charge transport and channel conductivity, relevant for ion channel research and biomaterials.