Iodine/soluble starch cryogel: An iodine-based antiseptic with instant water-solubility, improved stability, and...

Iodine (I₂) as a broad-spectrum antiseptic has been widely used for treating bacterial infections. However, I₂ has low water-solubility and sublimes under ambient conditions, which limits its practical antibacterial applications. The highly specific and sensitive reaction between I₂ and starch discovered 200 years ago has been extensively applied in analytical chemistry, but the antibacterial activity of the I₂-starch complex is rarely investigated. Herein, we develop a novel type of iodine-based antiseptics, iodine-soluble starch (I₂-SS) cryogel, which can dissolve in water instantly and almost completely kill bacteria in 10 min at 2 μg/mL of I₂. Although KI₃ and the commercially available povidone‑iodine (I₂-PVP) solutions show similar antibacterial efficacy, the high affinity of I₂ to SS largely enhances the shelf stability of the I₂-SS solution with ∼73 % I₂ left after one-week storage at room temperature. In sharp contrast, ∼8.5 % and ∼2.5 % I₂ are detected in KI₃ and I₂-PVP solutions, respectively. Mechanistic study reveals that the potent antibacterial effect of I₂-SS originates from its attack on multiple bacterial targets. The outstanding antibacterial activity, capability of accelerating wound healing, and good biocompatibility of I₂-SS are verified through further in vivo experiments. This work may promote the development of next-generation iodine-based antiseptics for clinical use.