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Sac embolization of abdominal aortic aneurysms (AAAs) remains clinically limited by endoleak recurrences. These recurrences are correlated with recanalization due to the presence of endothelial lining and matrix metalloproteinases (MMPs)‐mediated aneurysm progression. This study incorporates doxycycline (DOX), a well‐known sclerosant and MMPs inhibitor, into a shear‐thinning biomaterial (STB)‐based vascular embolizing hydrogel. The addition of DOX is expected to improve embolizing efficacy while preventing endoleaks by inhibiting MMP activity and promoting endothelial removal. The results show that STBs containing 4.5% w/w silicate nanoplatelet and 0.3% w/v of DOX are injectable and have a twofold increase in storage modulus compared to those without DOX. STB‐DOX hydrogels also reduced clotting time by 33% compared to untreated blood. The burst release of DOX from the hydrogels show sclerosing effects after 6 h in an ex vivo pig aorta model. Sustained release of DOX from hydrogels on endothelial cells shows MMP inhibition (approximately an order of magnitude larger than control groups) after 7 days. The hydrogels successfully occlude a patient‐derived abdominal aneurysm model at physiological blood pressures and flow rates. The sclerosing and MMP inhibition characteristics in the engineered multifunctional STB‐DOX hydrogels may provide promising opportunities for the efficient embolization of aneurysms in blood vessels. [ABSTRACT FROM AUTHOR]

Abstract: This study reports the development of a microfluidic system capable of repeated infusions of anti‐inflammatory factors post‐implantation for use as a coating for neural probes. This system consists of a microchannel in a thin gelatin methacryloyl–polyethylene glycol composite hydrogel surrounded by a porous polydimethylsiloxane membrane, where the hydrogel can be dried to increase the stiffness for easy insertion. Reswelling allows the perfusion of interleukin (IL)‐4 and dexamethasone as anti‐inflammatory factors through the channel with minimal burst release and significant amounts of IL‐4 are observed to release for up to 96 h post‐infusion. Repeated injections of IL‐4 increase the ratio of prohealing M2 versus proinflammatory M1 phenotypes of macrophages encapsulated in the hydrogel by sixfold compared with a single injection, over a 2‐week period. These repeated infusions also significantly downregulate the expression of inflammatory markers tumor necrosis factor‐α and IL‐6 in astrocytes encapsulated in hydrogel. To demonstrate the system as a coating of neural probes for in vivo applications, a prototype device is further fabricated, where a thin dual‐layered microfluidic system is integrated onto a metal probe. Such a drug delivery system can help reduce the formation of a glial scar around neural probes. [ABSTRACT FROM AUTHOR]

An emerging approach to improve the physicobiochemical properties and the multifunctionality of biomaterials is to incorporate functional nanomaterials (NMs) onto 2D surfaces and into 3D hydrogel networks. This approach is starting to generate promising advanced functional materials such as self‐assembled monolayers (SAMs) and nanocomposite (NC) hydrogels of NMs with remarkable properties and tailored functionalities that are beneficial for a variety of biomedical applications, including tissue engineering, drug delivery, and developing biosensors. A wide range of NMs, such as carbon‐, metal‐, and silica‐based NMs, can be integrated into 2D and 3D biomaterial formulations due to their unique characteristics, such as magnetic properties, electrical properties, stimuli responsiveness, hydrophobicity/hydrophilicity, and chemical composition. The highly ordered nano‐ or microscale assemblies of NMs on surfaces alter the original properties of the NMs and add enhanced and/or synergetic and novel features to the final SAMs of the NM constructs. Furthermore, the incorporation of NMs into polymeric hydrogel networks reinforces the (soft) polymer matrix such that the formed NC hydrogels show extraordinary mechanical properties with superior biological properties. [ABSTRACT FROM AUTHOR]