The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/ppsc.201900298. Ratiometric fluorescent probes have many advantages including improved sensitivity, high reliability and accuracy, visualization sensing, etc. Herein, the development of metal nanoclusters (NCs)-based ratiometric fluorescent probes in the recent years is summarized. NCs, an emerging new class of fluorescent nanomaterials, have demonstrated excellent optical properties, good biocompatibility, great aqueous solubility, low cost, and simple synthesis, and NCs-based ratiometric fluorescent probes have attracted much attention. In this progress report, the preparation and properties of NCs and the design of ratiometric fluorescent probes are summarized. Sensing of a broad range of analytes including cations, gas, small molecules, macromolecules, temperature, and pH is discussed. In addition, the challenges and future directions for NCs-based ratiometric fluorescent probes are also presented.
As a chronic degenerative joint disease, osteoarthritis is among the most common diseases all over the world. In osteoarthritis, inflammation plays an important role in the generation of joint symptoms and the development of disease. When the programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint is blocked, the antitumor immunity will be enhanced. We aim to illustrate the function of PD-L1 in osteoarthritis. Osteoarthritis in mice was induced by the injection of collagenase or anterior cruciate ligament transection (ACLT). Anti-PD-L1 was employed to block the signal of PD-L1. Knee joints histological sections were stained by Safranin-O. The level of cytokine was checked by enzyme-linked immunosorbent assay (ELISA) and mRNA level was shown by quantitative reverse transcriptase polymerase chain reaction. The blockade of PD-L1 signal up-regulated inflammatory response and promoted the development of osteoarthritis in mice. The inflammatory cytokine interleukin-6 and tumor necrosis factor-α expression were promoted by PD-L1 blocking in macrophages. Osteoarthritis was aggravated when the expression of inflammatory cytokine is elevated in macrophages. Our results indicated that the blockade of PD-L1 signal in macrophages elevates the expression of inflammatory cytokine and promotes the development of osteoarthritis in mice, which could be utilized as a potential diagnostic and therapeutic target for osteoarthritis patients.
As a kind of temperature‐responsive hydrogel, polystyrene‐co‐poly(N‐isopropylacrylamide)/poly(N‐isopropylacrylamide) (PS‐co‐PNIPAM/PNIPAM) core–shell nanoparticles prepared by two‐step copolymerization are widely studied and used because of their specific structures and properties. Unlike most reports about the steady stability of PS‐co‐PNIPAM/PNIPAM core–shell nanoparticle hydrogel emulsion, in this work, the PS‐co‐PNIPAM/PNIPAM core–shell nanoparticle hydrogel emulsion (symbolized as PS/PNIPAM hydrogel emulsion), which is prepared after the second step of synthesis and without washing out a large number of PNIPAM polymer segments, shows a reversible temperature‐dependent sol–gel transition characteristic during the temperature range of 34–80 °C. The PS/PNIPAM hydrogel emulsion is a normal solution at room temperature, and it changes from a sol to a gel statue when the temperature approaches up to low critical solution temperature (LCST). As the temperature continues to increase, the gel (core–shell nanoparticles as the crosslinkers and the linear PNIPAM chain as the 3D gel network) of the PS/PNIPAM hydrogel emulsion gradually shrinks and drains linearly. Compared with most crosslinked hydrogels, the hydrogel here can be arbitrarily changed in shape according to use needs, which is convenient for use, transportation, and storage. Here a new route is provided for the preparation of a PS/PNIPAM core–shell hydrogel nanoparticle system, as well as a new supramolecular crosslinking sol–gel system for application in biomedical materials, sensors, biological separation, drug release, macromolecular adsorption, and purification.
In article number 1900298 Yingnan Jiang, Chuanxi Wang, and co‐workers review the preparation and properties of nanoclusters and the design of ratiometric fluorescent probes. A broad range of analytes including cations, gas, small molecules, macromolecules, temperature, and pH are discussed. The challenges and future directions for nanoclusters‐based ratiometric fluorescent probes are also presented.
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