Hybrid suture coating for dual-staged control over antibacterial actions to match well wound healing progression.

Absorbable sutures have moved to the forefront in surgical fields with a huge market. Antibacterial activity is one indispensable feature for the next generation of absorbable sutures. This study develops a simple and cost-effective coating method to endow sutures with staged control over antibacterial actions to achieve enhanced dual stages of the wound healing process. This method is achieved in aqueous solution under mild conditions without the usage of any organic solvent and reserves the fundamental properties of suture materials, based on the pH-dependent reversible self-polymerization of tannic acid (TA) together with the strong adhesion of poly (tannic acid) (PTA) not only toward the suture surface but also with TA. Just by changing pH of TA solution, a hybrid coating (MPTA) composed of PTA and TA could be readily formed on the commercialized sutures originating from synthetic and natural materials. In the initial post-surgery stage, wound sites are susceptible to aseptic and/or bacterial inflammation. The resulting acid conditions induce burst release of antibacterial TA mostly coming from the adsorbed TA monomer. In the later stage, TA release is tailored totally depending on the pH conditions determined by the healing degree of wounds, allowing the sustained antibacterial prevention in a biologically adjustable manner. Thus, antibacterial MPTA coating meets the rigid requirements that differ distinctly during two major wound healing stages. Nontoxic MPTA coating on sutures leads to excellent post-implantation outcomes regarding bacterial prevention/elimination, anti-inflammation, tissue repair and wound healing. Moreover, MPTA coating provides sutures with a robust platform for functional expansion due to the matrix-independent adhesive ability of PTA.

Structural Transformation in Metal-Organic Frameworks for Reversible Binding of Oxygen.

Polycyclic aromatic derivatives can trap 1 O2 to form endoperoxides (EPOs) for O2 storage and as sources of reactive oxygen species. However, these materials suffer from structural amorphism, which limit both practical applications and fundamental studies on their structural optimization for O2 capture and release. Metal-organic frameworks (MOFs) offer advantages in O2 binding, such as clear structure-performance relationships and precise controllability. Herein, we report the reversible binding of O2 is realized via the chemical transformation between anthracene-based and the corresponding EPO-based MOF. It is shown that anthracene-based MOF, the framework featuring linkers with polycyclic aromatic structure, can rapidly trap 1 O2 to form EPOs and can be restored upon UV irradiation or heating to release O2 . Furthermore, we confirm that photosensitizer-incorporated anthracene-based MOF are promising candidates for reversible O2 carriers controlled by switching Vis/UV irradiation.