Transport of Molecular Iodine From Antiseptic Iodophors across Hydrophilic–lipophilic Interfaces: Influence of Phospholipids

High Resolution Image Download MS PowerPoint Slide The release and transport of molecular iodine (I 2 ) from antiseptic iodophors across hydrophilic–lipophilic interfaces were studied to understand the impact of carrier polymers and phospholipids on release and transport of molecular iodine across biologically relevant interfaces. Five commercial povidone-iodine formulations and one modified dextrin-iodine complex, each standardized to 1% thiosulfate titratable iodine, were tested using a heptane–water interface model. Iodine release was quantified by both UV–vis spectroscopy and thiosulfate titration with and without phospholipid-rich lipophilic phase. Dilution significantly increased I 2 release, with dextrin-iodine achieving near-complete transfer at higher dilutions due to reduced polymer-iodine binding. Phospholipids enhanced iodine transport via charge-transfer interactions, with release kinetics well-fitted by Weibull and Michaelis–Menten models ( R 2 > 0.988). For aqueous iodophors, a dilution ratio of 8–10 fold is optimal, enabling dextrin-iodine to attain rapid 100% iodine release while povidone-iodine formulations released 40.3–68.1% of their iodine content in the presence of phospholipids. The active biocide in iodophors is molecular iodine and these findings highlight the critical role of iodophor carrier/composition and lipid interactions in maximizing iodine delivery, offering insight for developing next-generation antiseptic formulations.