Main phase transition of hydroperoxidized SOPC bilayers

Lipid hydroperoxidation significantly changes membrane biophysical properties, yet its effect on the main phase transition of unsaturated phospholipids remains unclear. Here, we investigate how hydroperoxidation of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) influences its phase behavior. Bilayers composed of SOPC and increasing fractions of hydroperoxidized SOPC (SOPC-OOH) were analyzed using differential scanning calorimetry, the band shift of the new solvatochromic probe A10, and Laurdan generalized polarization fluorescence. The incorporation of hydroperoxidized acyl chains perturbed membrane thermodynamics, revealing a complex phase-transition landscape governed by the interplay between acyl-chain ordering and the spatial distribution of -OOH groups. These results highlight the sensitivity of lipid phase behavior to oxidative modifications at the molecular level and provide new insights into how lipid peroxidation modulates membrane organization in cellular and biomimetic systems.