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

Iodine (I 2 ) as a broad-spectrum antiseptic has been widely used for treating bacterial infections. However, I 2 has low water-solubility and sublimes under ambient conditions, which limits its practical antibacterial applications. The highly specific and sensitive reaction between I 2 and starch discovered 200 years ago has been extensively applied in analytical chemistry, but the antibacterial activity of the I 2  − starch complex is rarely investigated. Herein, we develop a novel type of iodine-based antiseptics, iodine−soluble starch (I 2 -SS) cryogel, which can dissolve in water instantly and almost completely kill bacteria in 10 min at 2 μg/mL of I 2 . Although KI 3 and the commercially available povidone‑iodine (I 2 -PVP) solutions show similar antibacterial efficacy, the high affinity of I 2 to SS largely enhances the shelf stability of the I 2 -SS solution with ~75 % I 2 left after one-week storage at room temperature. In sharp contrast, ~8 % and ~ 3 % I 2 are detected in KI 3 and I 2 -PVP solutions, respectively. Mechanistic study reveals that the potent antibacterial effect of I 2 -SS originates from its attack on multiple bacterial targets. The outstanding antibacterial activity, capability of accelerating wound healing, and good biocompatibility of I 2 -SS are verified through further in vivo experiments. This work may promote the development of next-generation iodine-based antiseptics for clinical use.