Cholesterol Reshapes Electroporation Energetics in Phosphatidylcholine Model Membranes

Cholesterol modulates membrane packing and mechanics, but how concentration reshapes the free-energy landscape from water-defect nucleation to pore expansion remains incompletely resolved. Here, all-atom molecular dynamics, a continuous joint pore coordinate, umbrella sampling under applied potentials, and unbiased direct-field trajectories were combined for a controlled 300 K DMPC/cholesterol series. Across the low-to-medium range, cholesterol increased the characteristic nucleation-region free-energy cost and pore-edge line tension while making metastable pore states shallower; increasing potential lowered hydrated-defect growth costs. Direct-field simulations at composition-specific operational pore-onset potentials separately showed composition-dependent channel timing and pore lifetimes, operationally defined by continuous-water connectivity. Matched DMPC, POPC, and DOPC membranes containing 20 mol % cholesterol showed lipid-dependent responses in nucleation-region profiles, core hydration, charge-density-derived relative electrostatic potentials, and pore structure. The 66 mol % DMPC system defined a distinct high-cholesterol response that departed from lower-concentration trends. Overall, electroporation emerged as a composition- and field-dependent remodeling of the poration landscape, with the matched 20 mol % systems further revealing lipid-dependent responses.