Polycationic calixarene micellar aggregate as a novel iodophor platform for on-demand iodine release to bacteria

Iodine is the most potent antiseptic agent used in clinical applications, but its volatility and toxicity are serious drawbacks that are stimulating the search of new strategies to achieve formulations stable at low iodine concentration. Here, we report that polycationic micellar aggregates, formed by the self-assembling of the amphiphilic choline-calix[4]arene derivative (CholCalix) in aqueous medium, are able to complex triiodide anions (I₃^-) both in solution and in solid phase. This novel iodophor enhances the stability of 0.01 % iodine and 0.1 % povidone iodine (PVP-I) water solutions. The binding properties of the CholCalix aggregate towards iodine were investigated by UV-vis spectrophotometry, dynamic light scattering, and isothermal titration calorimetry. The bactericidal activity of the complexes was proved against a specimen of Gram-negative bacteria (Escherichia coli ATCC 10536) by time-killing assay. The molecular iodine release profile suggests that the calixarene-based micellar nanocarrier may succeed as a novel iodophor for on-demand I₂ release.