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It is highly desirable but challenging to realize efficient photoreforming of plastic waste over metal-free semiconductors. Here, we synthesized metal-free carbon nitride porous microtube (CNxPM) photocatalysts by carrying out a pyrolysis of the supramolecular assembly formed by the self-assembly of L -arginine (L -Arg) and melamine, the modification of L -Arg rationally engineering the microstructure and electronic structure of the CNxPM system for efficient visible-light-driven photoreforming of poly(ethylene terephthalate) (PET) to hydrogen (H2) and high-value chemicals. In particular, the amount of formate converted from PET substrate under visible light was highest in metal-free semiconductors without any co-catalyst reported so far, presenting the first example of visible-light-driven photoreforming of PET over a completely metal-free single-component semiconductor without any co-catalyst. [ABSTRACT FROM AUTHOR]

Responsive photonic crystals (RPCs) with tunable optical signals have intrinsic advantages in the construction of colorimetric sensors. Here, we report a dual-channel photonic crystal sensor fabricated by suspending ETPTA-TPM inverse opal microspheres (IOMs) in an aqueous ferrofluid for the detection of magnetic field strength. These nonmagnetic IOMs will quickly arrange into chain structures along the field direction, leading to the quenching of reflection signals in several minutes. Generally, a stronger magnetic field causes a faster quenching and a larger decline of reflection intensity. Based on the above correlation, a dual-channel sensor was fabricated to detect magnetic field strength in a broad range according to reflection quenching time and quenching ratio. The sensing of the magnetic field is accurate, stable and reliable, because the working of the PC sensor only involves magnetic tuning but no magnetic assembly. [ABSTRACT FROM AUTHOR]

Neutrophil transendothelial migration (TEM) is an essential physiological process that regulates the recruitment of neutrophils in response to inflammatory signals. Herein, a versatile hydrogel scaffold is embedded in a microfluidic platform that supports an endothelial cell layer cultured in the vertical direction and highly stable chemical gradients; this construct is employed to mimic the in vivo neutrophil TEM process. We found that the number of neutrophils migrating across the endothelial cell layer is dependent on the presented chemoattractant concentration and the spatial profile of the chemical gradient. Endothelial cells play a critical role in neutrophil TEM by promoting neutrophil morphological changes as well as expressing surface receptor molecules that are indispensable for inducing neutrophil attachment and migration. Furthermore, the microfluidic device also supports competing chemoattractant gradients to facilitate neutrophil TEM studies in complex microenvironments that more accurately model the in vivo system than simplified microenvironments without the complexity of chemical gradients. This work demonstrates that combinations of any two different chemoattractants induce more significant neutrophil migration than a single chemoattractant in the same total amount, indicating synergistic effects between distinct chemoattractants. The in vitro reconstitution of neutrophil TEM successfully translates planar neutrophil movement into in vivo-like neutrophil recruitment and accelerates understanding of cellular interactions between neutrophils and endothelial cells within the complicated physiological milieu. [ABSTRACT FROM AUTHOR]

Neutrophils are critical inflammatory cells; thus, it is important to characterize the effects of drugs on neutrophil function in the context of inflammatory diseases. Herein, chemically guided neutrophil migration, known as chemotaxis, is studied in the context of drug treatment at the single cell level using a microfluidic platform, complemented by cell viability assays and calcium imaging. Three representative drugs known to inhibit surface receptor expression, signaling enzyme activity, and the elevation of intracellular Ca2+ levels, each playing a significant role in neutrophil chemotactic pathways, are used to examine the in vitro drug effects on cellular behaviors. The microfluidic device establishes a stable concentration gradient of chemokines across a cell culture chamber so that neutrophil migration can be monitored under various drug-exposure conditions. Different time- and concentration-dependent regulatory effects were observed by comparing the motility, polarization, and effectiveness of neutrophil chemotaxis in response to the three drugs. Viability assays revealed distinct drug capabilities in reducing neutrophil viability while calcium imaging clarified the role of Ca2+ in the neutrophil chemotaxis. This study provides mechanistic insight into the drug effects on neutrophil function, facilitating comparison of current and potential pharmaceutical approaches. [ABSTRACT FROM AUTHOR]

A quartz crystal microbalance with dissipation monitoring (QCM-D) sensor was developed for highly sensitive and specific detection of mercury(ii) ions (Hg2) with a tunable dynamic range, using oligonucleotide-functionalized gold nanoparticles (GNPs) for both frequency and dissipation amplification. The fabrication of the sensor employed a ‘sandwich-type’ strategy, and formation of T–Hg2–T structures in linker DNA reduced the hybridization of the GNPs-tagged DNA on the gold electrode, which could be used as the molecular switch for Hg2뇩. This QCM-D mercury sensor showed a linear response of 10–200 nM, with detection limits of 4 nM and 7 nM for frequency and dissipation measurements, respectively. Moreover, the dynamic range of the sensor could be tuned by simply altering the concentration of linker DNA without designing new sensors in the cases where detection of Hg2 different levels is required. This sensor afforded excellent selectivity toward Hg2犉ꥪ랝 with other potential coexisting metal ions. The feasibility of the sensor was demonstrated by analyzing Hg2+spiked tap- and lake-water samples with satisfactory recoveries. The proposed approach extended the application of the QCM-D system in metal ions sensing, and could be adopted for the detection of other analytes when complemented with the use of functional DNA structures. [ABSTRACT FROM AUTHOR]

The n = 1 Ruddlesden-Popper (RP) phases LaSrM(0.5)Ru(0.5)O(4±δ) (M = Co, Ni and Zn) have been prepared by solid state reactions and structurally characterized by powder X-ray and electron diffraction. All the samples adopt the tetragonal I4/mmm space group with random M and Ru cation occupation on the B-sites. The potential causes of no cation ordering are discussed. A combined analysis of the tolerance factors, the distortion of the octahedral coordination of M and Ru cations and the magnetic interactions between M and Ru cations provide a better understanding for forming a phase with 3D cation ordering on the B-sites in the n = 1 RP phases. The investigation of XPS spectra suggests that the transition element species exist as mixed ion pairs, Ru((4-δ)+)-Ru(4+)↔ Co(2+)-Co(3+) in LaSrCo(0.5)Ru(0.5)O(4), and Ru(4+)-Ru((4+δ)+)↔ Ni(+)-Ni(2+) in LaSrNi(0.5)Ru(0.5)O(4), which is consistent with cation disorder over the B sites. LaSrCo(0.5)Ru(0.5)O(4) shows a weakly ferromagnetic behaviour below 50 K; LaSrNi(0.5)Ru(0.5)O(4) is evidenced by the presence of long-range magnetic ordering at a Néel temperature of 125 K, and LaSrZn(0.5)Ru(0.5)O(4) exhibits a paramagnetic behaviour down to 5 K. Due to atomic disorder, Ru4d, O2p covalent coupling is weakened, strengthening the intraatomic spin-spin coupling among the π* electrons. Charge transfer between Ru and Co or Ru and Ni, as well as the increasing overlap of both nearest-neighbour and next-nearest-neighbour Ru 4d electrons due to atomic disorder, favour the formation of ferromagnetic interactions. Although antiferromagnetism is dominant, particularly in LaSrNi(0.5)Ru(0.5)O(4), ferromagnetic interactions are stronger in the title compounds than in the related La(2)MRuO(6) (M = Co, Ni) double perovskites where the B-site cations are ordered.