Mechanical Enhancement and Kinetics Regulation of Fmoc‐Diphenylalanine Hydrogels by Thioflavin T

Hydrogel delivery systems can leverage therapeutically beneficial outcomes of drug delivery and have found clinical use. Hydrogels can provide spatial and temporal control over the release of various therapeutic agents, including small-molecule drugs, macromolecular drugs and cells. Owing to their tunable physical properties, controllable degradability and capability to protect labile drugs from degradation, hydrogels serve as a platform in which various physiochemical interactions with the encapsulated drugs control their release. In this Review, we cover multiscale mechanisms underlying the design of hydrogel drug delivery systems, focusing on physical and chemical properties of the hydrogel network and the hydrogel-drug interactions across the network, mesh, and molecular (or atomistic) scales. We discuss how different mechanisms interact and can be integrated to exert fine control in time and space over the drug presentation. We also collect experimental release data from the literature, review clinical translation to date of these systems, and present quantitative comparisons between different systems to provide guidelines for the rational design of hydrogel delivery systems.

Intense efforts to detect, diagnose, and analyze the kinetic and structural properties of amyloid fibrils have generated a powerful toolkit of amyloid-specific molecular probes. Since its first description in 1959, the fluorescent dye Thioflavin-T (ThT) has become among the most widely used "gold standards" for selectively staining and identifying amyloid fibrils both in vivo and in vitro. The large enhancement of its fluorescence emission upon binding to fibrils makes ThT a particularly powerful and convenient tool. Despite its widespread use in clinical and basic science applications, the molecular mechanism for the ability of ThT to recognize diverse types of amyloid fibrils and for the dye's characteristic fluorescence has only begun to be elucidated. Here, we review recent progress in the understanding of ThT-fibril interactions at an atomic resolution. These studies have yielded important insights into amyloid structures and the processes of fibril formation, and they also offer guidance for designing the next generation of amyloid assembly diagnostics, inhibitors, and therapeutics. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Ag/Ag@AgCl/ZnO hybrid nanostructures are embedded in a hydrogel by a simple two-step technique. The Ag/Ag@AgCl nanostructures are assembled in the hydrogel via ultraviolet light chemical reduction followed by incorporation of ZnO nanostructures by NaOH precipitation. The hydrogel accelerates wound healing and exhibits high antibacterial efficiency against both Escherichia coli and Staphylococcus aureus under visible light irradiation. The Ag/Ag@AgCl nanostructures enhance the photocatalytic and antibacterial activity of ZnO due to the enhancement of reactive oxygen species by visible light. This hydrogel system kills 95.95% of E. coli and 98.49% of S. aureus within 20 min upon exposure to simulated visible light, and rapid sterilization plays a crucial role in wound healing. In addition, this system provides controllable, sustained release of silver and zinc ions over a period of 21 days arising from the reversible swelling-shrinking transition of the hydrogel triggered by the changing pH value in the biological environment. About 90% Zn2+ release is observed in the acidic environment after 3 days, whereas only 10% Zn2+ release occurs in the neutral environment after 21 days. In vivo results show that release of Ag+ and Zn2+ stimulates the immune function to produce a large number of white blood cells and neutrophils (2-4 times more than the control), thereby producing the synergistic antibacterial effects and accelerated wound healing.