Investigating Heat-Induced Phase Transitions in POPC Lipid Bilayers Using Molecular Dynamics Simulations

In this study, the effect of heat shock on the cell membrane was investigated using molecular dynamics (MD) simulations. Specifically, we examined the structural and dynamic behavior of a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayer as it was exposed to increasing temperatures ranging from 310K to 340K. The results revealed a significant transition in membrane behavior as temperature increased, particularly at 330K and 340K, where the bilayer exhibited characteristics of a fluid disordered phase. This transition was marked by an increase in the area per lipid, a decrease in bilayer thickness, and a reduction in the deuterium order parameter (Scd), indicating increased molecular disorder and membrane fluidity. Additionally, the number of hydrogen bonds between lipid head groups and surrounding water molecules declined, weakening electrostatic interactions and promoting bilayer permeability. At 330K and 340K, these changes contributed to the formation of transient pores, which could facilitate molecular transport across the bilayer. The optimal temperature for maintaining membrane stability while enhancing molecular diffusion was found to be 320K, where the bilayer retained an ordered structure and displayed increased lipid mobility without significant disruption. These findings provide valuable insights into the thermal regulation of membrane behavior, which has critical implications for processes such as drug delivery, gene transfection, and thermal therapy. Molecular dynamics simulations at the atomistic level allow us to uncover intricate details of membrane phase transitions that are challenging to observe experimentally.