Atomic-level defects in van der Waals (vdW) materials
are essential
building blocks for quantum technologies and quantum sensing applications.
The layered magnetic semiconductor CrSBr is an outstanding candidate
for exploring optically active defects because of a direct gap, in
addition to a rich magnetic phase diagram, including a recently hypothesized
defect-induced magnetic order at low temperature. Here, we show optically
active defects in CrSBr that are probes of the local magnetic environment.
We observe a spectrally narrow (1 meV) defect emission in CrSBr that
is correlated with both the bulk magnetic order and an additional
low-temperature, defect-induced magnetic order. We elucidate the origin
of this magnetic order in the context of local and nonlocal exchange
coupling effects. Our work establishes vdW magnets like CrSBr as an
exceptional platform to optically study defects that are correlated
with the magnetic lattice. We anticipate that controlled defect creation
allows for tailor-made complex magnetic textures and phases with direct
optical access.
The increasing demand for disposable textiles for multi‐cleansing purposes has led to an uncontrollable accumulation of macro‐ and microdebris in water bodies, resulting in major environmental disruptions and a threat to ecosystems. Considering the emerging nature of this type of contamination, there is still no current treatment to tackle this environmental problem. Here, self‐propelled bismuth tungstate microrobots that can actively move under light irradiation, swarm, and destroy disposable textiles through oxidative pathways are presented. Upon sun‐like illumination, these micromachines attack and degrade both the intertwined network of natural/synthetic textiles and their organic ingredients that are subsequently released into the water. The high efficiency arises from the enhanced intimate contact between the self‐propelled microrobots and the surface of the textiles. This work provides a unique strategy to treat emerging solid waste contamination in water bodies at mild conditions by combining photoactivated microrobots, collective behavior, and photocatalysis.
Urinary‐based infections affect millions of people worldwide. Such bacterial infections are mainly caused by Escherichia coli (E. coli) biofilm formation in the bladder and/or urinary catheters. Herein, the authors present a hybrid enzyme/photocatalytic microrobot, based on urease‐immobilized TiO2/CdS nanotube bundles, that can swim in urea as a biocompatible fuel and respond to visible light. Upon illumination for 2 h, these microrobots are able to remove almost 90% of bacterial biofilm, due to the generation of reactive radicals, while bare TiO2/CdS photocatalysts (non‐motile) or urease‐coated microrobots in the dark do not show any toxic effect. These results indicate a synergistic effect between the self‐propulsion provided by the enzyme and the photocatalytic activity induced under light stimuli. This work provides a photo‐biocatalytic approach for the design of efficient light‐driven microrobots with promising applications in microbiology and biomedicine.
A switchable material with a smart antimicrobial dual‐action functionality, which is based on a highly stretchable silicon polymer gradiently doped with polyyrrole, is proposed. The material exhibits superhydrophobic and self‐cleaning properties, high aerophilicity as well as the possibility of smart, electrically triggerable release of an incorporated drug. During the immersion of the material in water, an air gap is formed on its surface which prevents a formation of biofouling, attachment of microorganisms, and burst release of the incorporated drug. An application of external electric field switches the surface properties from the superhydrophobic to highly hydrophilic state that enables a wetting of the material surface and electrically triggered release of a loaded drug. After the electric field switching off and sample drying, the material surface returns to its intrinsic superhydrophobic state with the original self‐cleaning properties so that the material surface can be simply cleaned, removing the bacteria. High flexibility and stretchability are additional favorable properties of the proposed smart antimicrobial material, making it a suitable candidate for a range of medical and related applications.
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