Search

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Spatiotemporally controlled two‐photon photodegradation of hydrogels has gained increasing attention for high‐precision subtractive tissue engineering. However, conventional photolabile hydrogels often have poor efficiency upon two‐photon excitation in the near‐infrared (NIR) region and thus require high laser dosage that may compromise cell activity. As a result, high‐speed two‐photon hydrogel erosion in the presence of cells remains challenging. Here we introduce the design and synthesis of efficient coumarin‐based photodegradable hydrogels to overcome these limitations. A set of photolabile coumarin‐functionalized polyethylene glycol linkers are synthesized through a Passerini multicomponent reaction. After mixing these linkers with thiolated hyaluronic acid, semi‐synthetic photodegradable hydrogels are formed in situ via Michael addition crosslinking. The efficiency of photodegradation in these hydrogels is significantly higher than that in nitrobenzyl counterparts upon two‐photon irradiation at 780 nm. A complex microfluidic network mimicking the bone microarchitecture is successfully fabricated in preformed coumarin hydrogels at high speeds of up to 300 mm s−1 and low laser dosage down to 10 mW. Further, we demonstrate fast two‐photon printing of hollow microchannels inside a hydrogel to spatiotemporally direct cell migration in 3D. Collectively, these hydrogels may open new avenues for fast laser‐guided tissue fabrication at high spatial resolution. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have shown great research and application value in various types of hydrosilylation reactions. However, studies on photocatalysis‐induced hydrosilylation using MOFs are extremely rare. Metal nanoparticles (MNPs)@MOFs are extensively studied for their excellent structural tunability and photocatalytic activity, but there are few reports on their application in photocatalytic hydrosilylation. Here, a novel photocatalyst consisting of platinum (Pt) nanoparticles immobilized in a MOF framework is synthesized and used for photocatalytic hydrosilylation. The effects of various factors on hydrosilylation conversion are investigated, including catalyst concentration, substrate ratio, and irradiation intensity. Furthermore, the photoreactivity of the synthesized Pt catalyst is evaluated in the presence of different concentrations of 2‐chlorothixanthone as a photosensitizer. It is noteworthy that the conversion of the reaction increases with increasing catalyst concentration or photosensitizer concentration, whereas increasing the polymethylhydrosiloxane content does not lead to a significant increase in conversion. This study demonstrates the potential of MNPs@MOFs as efficient photocatalysts for photoinduced hydrosilylation reactions and paves the way for future applications in this area. [ABSTRACT FROM AUTHOR]

BACKGROUND: Compromised autophagy, including impaired mitophagy and lysosomal function, plays pivotal roles in Alzheimer's disease (AD). Urolithin A (UA) is a gut microbial metabolite of ellagic acid that stimulates mitophagy. The effects of UA's long‐term treatment of AD and mechanisms of action are unknown. METHODS: We addressed these questions in three mouse models of AD with behavioral, electrophysiological, biochemical, and bioinformatic approaches. RESULTS: Long‐term UA treatment significantly improved learning, memory, and olfactory function in different AD transgenic mice. UA also reduced amyloid beta (Aβ) and tau pathologies and enhanced long‐term potentiation. UA induced mitophagy via increasing lysosomal functions. UA improved cellular lysosomal function and normalized lysosomal cathepsins, primarily cathepsin Z, to restore lysosomal function in AD, indicating the critical role of cathepsins in UA‐induced therapeutic effects on AD. CONCLUSIONS: Our study highlights the importance of lysosomal dysfunction in AD etiology and points to the high translational potential of UA. Highlights: Long‐term urolithin A (UA) treatment improved learning, memory, and olfactory function in Alzheimer's disease (AD) mice.UA restored lysosomal functions in part by regulating cathepsin Z (Ctsz) protein.UA modulates immune responses and AD‐specific pathophysiological pathways. [ABSTRACT FROM AUTHOR]

Let G be a finite undirected simple connected graph with vertex set V (G) and edge set E (G). A vertex u ∈ V (G) resolves two elements (vertices or edges) v , w ∈ V (G) ∪ E (G) if d (u , v) ≠ d (u , w). A subset S m of vertices in G is called a mixed metric generator for G if every two distinct elements (vertices and edges) of G are resolved by some vertices of S m . The minimum cardinality of a mixed metric generator for G is called the mixed metric dimension and is denoted by dim m (G). In this paper, we study the mixed metric dimension for the plane graph of web graph n and convex polytope n . [ABSTRACT FROM AUTHOR]