Antiseptic povidone-iodine encapsulating edible phospholipid gels

Abstract

Lecithin-based gels are generally made by adding water or water/surfactant systems into lecithin dissolved solvents, a process known as organogel formation. Organogels are stable viscoelastic micellar phospholipid aggregates with drug encapsulating capabilities. In this work, we demonstrate an alternative approach in which soy lecithin/alginate (1:1) gels were fabricated from aqueous solutions by divalent cationic crosslinking without using any solvents. As a model drug, we used a common antiseptic, povidone iodine complex (PVPI) that has been recently demonstrated to be effective and fast acting against SARS-CoV-2 virus. Rheological characteristics of gelling dynamics were studied with isothermal oscillation shear measurements. The gels were shown to encapsulate PVPI complex (7 wt%), during ionic cross-linking. Soy lecithin significantly minimized antiseptic loss during crosslinking. At the end of 1 h of gelling process, lecithin free gels lost 20% of the loaded drug whereas composite gels lost about 12% back into the crosslinking solution. In water, drug release from the composite gels was slower compared to lecithin-free gels. This effect was more pronounced in simulated gastric fluid, indicating that the composite gels could act as slow dissociating matrices for hydrophilic drugs in gastric fluid. Optical density (600 nm) measurements showed that PVPI loaded composite gels effectively disinfected aqueous media contaminated with both gram-negative and gram-positive bacteria. This cost-effective fabrication process can be easily scaled up with potential applications such as wet tissue ulcer treatment and biodegradable field water purification additives targeting not only bacteria but also virulent water borne pathogens.