Sustained Release of Nitric Oxide-Mediated Angiogenesis and Nerve Repair by Mussel-Inspired Adaptable Microreservoirs for Brain Traumatic Injury Therapy.

Traumatic brain injury (TBI) triggers inflammatory response and glial scarring, thus substantially hindering brain tissue repair. This process is exacerbated by the accumulation of activated immunocytes at the injury site, which contributes to scar formation and impedes tissue repair. In this study, a mussel-inspired nitric oxide-release microreservoir (MINOR) that combines the features of reactive oxygen species (ROS) scavengers and sustained NO release to promote angiogenesis and neurogenesis is developed for TBI therapy. The injectable MINOR fabricated using a microfluidic device exhibits excellent monodispersity and gel-like self-healing properties, thus allowing the maintenance of its structural integrity and functionality upon injection. Furthermore, polydopamine in the MINOR enhances cell adhesion, significantly reduces ROS levels, and suppresses inflammation. Moreover, a nitric oxide (NO) donor embedded into the MINOR enables the sustained release of NO, thus facilitating angiogenesis and mitigating inflammatory responses. By harnessing these synergistic effects, the biocompatible MINOR demonstrates remarkable efficacy in enhancing recovery in mice. These findings benefit future therapeutic interventions for patients with TBI.

Distributed twist sensing using frequency-scanning φ-OTDR in a spun fiber.

In this paper, a novel distributed twist sensor based on frequency-scanning phase-sensitive optical time-domain reflectometry (φ-OTDR) in a spun fiber is proposed and demonstrated. Owing to the unique helical structure of the stress rods in the spun fiber, fiber twist gives rise to the variation of the effective refractive index of the transmitting light, which can be quantitatively retrieved through frequency shift using frequency-scanning φ-OTDR. The feasibility of distributed twist sensing has been verified by both simulation and experiment. For proof of concept, distributed twist sensing over a 136 m spun fiber with a 1 m spatial resolution is demonstrated, and the measured frequency shift shows a quadratic fitting dependence on the twist angle. In addition, the responses of both clockwise and counterclockwise twist directions have also been explored and the experiment result indicates that the twist direction can be discriminated since the frequency shift directions are opposite in the correlation spectrum. The proposed twist sensor possesses some outstanding advantages, including high sensitivity, distributed twist measurement and twist direction recognition capability, etc., which is very promising for specific applications in industry, e.g., structural health monitoring, bionic robots, etc.