A durable antifogging anionic-cationic surfactant complex for endoscopic lens applications

Fogging of endoscopic lenses significantly impairs intraoperative visual clarity and introduces non-negligible surgical safety risks during minimally invasive surgery. Current antifogging agents fail to balance application convenience with long-lasting efficacy, primarily due to poor interfacial adhesion to glass substrates, the standard substrate material for endoscopic lenses. This study designed a durable anionic-cationic antifogging surfactant complex by optimizing the controllable self-assembly guided by molecular dynamics simulations. The complex was a combination of anionic surfactant alcohol ether sulfate sodium (AEnS) and cationic dodecyltrimethylammonium chloride (DTAC), denoted as ADxx (subscripts indicate the anion-to-cation molar ratio). The equimolar AD55 enabled laterally continuous water films and ultrafast wetting within 0.25 s. Strong electrostatic interactions between anionic and cationic headgroups drive the formation of densely packed, hemispherical aggregates at the solid interface (proposed by MD simulations), which markedly suppresses surfactant diffusion at the interface, extending antifogging durability to 2 h (approximately four times that of current antifogging agents). In vivo laparoscopic experiments confirmed that AD55 completely prevents lens fogging and inhibits electrosurgical smoke adhesion throughout surgery when applied via a simple, single-step wipe-on protocol. AD55 is expected to offer a highly promising, clinically translatable antifogging strategy for endoscopic surgery by simple preparation, ultra-rapid wettability and long-term fog resistance.