Intestinal Delivery of Probiotics: Materials, Strategies, and Applications.

Probiotics with diverse and crucial properties and functions have attracted broad interest from many researchers, who adopt intestinal delivery of probiotics to modulate the gut microbiota. However, the major problems faced for the therapeutic applications of probiotics are the viability and colonization of probiotics during their processing, oral intake, and subsequent delivery to the gut. The challenges of simple oral delivery (stability, controllability, targeting, etc.) have greatly limited the use of probiotics in clinical therapies. Nanotechnology can endow the probiotics to be delivered to the intestine with improved survival rate and increased resistance to the adverse environment. Additionally, the progress in synthetic biology has created new opportunities for efficiently and purposefully designing and manipulating the probiotics. In this article, a brief overview of the types of probiotics for intestinal delivery, the current progress of different probiotic encapsulation strategies, including the chemical, physical, and genetic strategies and their combinations, and the emerging single-cell encapsulation strategies using nanocoating methods, is presented. The action mechanisms of probiotics that are responsible for eliciting beneficial effects are also briefly discussed. Finally, the therapeutic applications of engineered probiotics are discussed, and the future trends toward developing engineered probiotics with advanced features and improved health benefits are proposed.

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

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 povidone­iodine (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 âˆ¼2.5 % 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.