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All-inorganic metal halide perovskites have been actively investigated as promising energy-converting materials for abundant applications owing to their excellent electronic and optical properties. Three-dimensional (3D) CsPbBr3, two-dimensional (2D) CsPb2Br5, and zero-dimensional (0D) Cs4PbBr6 obtained by Cs–Pb–Br dimensional engineering at the molecular level open a new avenue for the development and application of metal halide perovskites. A continuously increasing number of studies are devoted to the phase transitions of 3D CsPbBr3, 2D CsPb2Br5 and 0D Cs4PbBr6 to improve the stability and electronic and optical properties of metal halide perovskites by forming multi-phase perovskite structures. Herein, recent advances in the phase transitions of these three materials are discussed systematically. The processes occurring during the reversible phase transitions of 3D CsPbBr3, 2D CsPb2Br5 and 0D Cs4PbBr6 are elaborated, and their reaction mechanisms are described. In addition, the latest applications of all-inorganic metal halide perovskites in photoelectric, electro-optical, and all-optical conversion processes are summarized. Finally, future research directions related to the development of inorganic metal halide perovskites for these applications are outlined. In summary, the phase transitions of all-inorganic perovskites provide attractive opportunities for multi-field applications. [ABSTRACT FROM AUTHOR]

In the realm of biological research, the invention of super-resolution microscopy (SRM) has enabled the visualization of ultrafine sub-cellular structures and their functions in live cells at the nano-scale level, beyond the diffraction limit, which has opened up a new window for advanced biomedical studies to unravel the complex unknown details of physiological disorders at the sub-cellular level with unprecedented resolution and clarity. However, most of the SRM techniques are highly reliant on the personalized special photophysical features of the fluorophores. In recent times, there has been an unprecedented surge in the development of robust new fluorophore systems with personalized features for various super-resolution imaging techniques. To date, xanthene, cyanine, oxazine and BODIPY cores have been authoritatively utilized as the basic fluorophore units in most of the small-molecule-based organic fluorescent probe designing strategies for SRM owing to their excellent photophysical characteristics and easy synthetic acquiescence. Since the future of next-generation SRM studies will be decided by the availability of advanced fluorescent probes and these four fluorescent building blocks will play an important role in progressive new fluorophore design, there is an urgent need to review the recent advancements in designing fluorophores for different SRM methods based on these fluorescent dye cores. This review article not only includes a comprehensive discussion about the recent developments in designing fluorescent probes for various SRM techniques based on these four important fluorophore building blocks with special emphasis on their effective integration into live cell super-resolution bio-imaging applications but also critically evaluates the background of each of the fluorescent dye cores to highlight their merits and demerits towards developing newer fluorescent probes for SRM. [ABSTRACT FROM AUTHOR]

Bioimaging and biosensing have garnered interest in early cancer diagnosis due to the ability of gaining in-depth insights into cellular functions and providing a wide range of diagnostic parameters. Emerging 2D materials of multielement MXenes and monoelement black phosphorous nanosheets (BPNSs) with unique intrinsic physicochemical properties such as a tunable bandgap and layer-dependent fluorescence, high carrier mobility and transport anisotropy, efficient fluorescence quenching capability, desirable light absorption and thermoelastic properties, and excellent biocompatibility and biosafety properties provide promising nano-platforms for bioimaging and biosensing applications. In view of the growing attention on the rising stars of the post-graphene age in the progress of bioimaging and biosensing, and their common feature characteristics as well as complementarity for constructing complexes, the main objective of this review is to reveal the recent advances in the design of MXene or BPNS based nanoplatforms in the field of bioimaging and biosensing. The preparation and surface functionalization methods, biosafety, and other important aspects of bioimaging and biosensing applications of MXenes and BPNSs have been assessed systematically, along with highlighting the main challenges in further biomedical application. The review not only focuses on the advancements in 2D materials for use in bioimaging and biosensing but also assesses the possibility of their future potential in bioapplications. [ABSTRACT FROM AUTHOR]

The impact of anthropogenic activity on chemical weathering is still an open and significant topic that requires clarification to improve the understanding of watershed evolution. We analyzed river water and rainwater samples to characterize the variation in hydrochemical characteristics and influencing factors. Samples were taken from the Liuxi River Basin (LRB), the only local drinking water supply for Guangzhou, and we studied geochemical parameters, major ions, and Si concentrations. Moreover, elemental ratios of end-members were determined and a modified-forward model was constructed to identify ion sources and estimate the chemical weathering rate (CWR) and anthropogenic input rate (AIR). Finally, we quantified the impacts of anthropogenic activity on the chemical weathering process. The results showed that the dominant hydrochemical type of river water was identified as HCO3–Ca, and rock weathering was the main contributor to river Na+, Mg2+, Ca2+ and HCO3−, whereas anthropogenic activity contributed the most to K+, Cl−, SO42−, and NO3−. The relatively high silicate weathering rate (SWR) (17.8–18.4 t per km2 per year) and AIR (37.8–60.3 t per km2 per year) were mainly attributed to erosion by nitric and sulfuric acid. The contribution rate of these acids to CWR could be regarded as a proxy quantifying the impact of anthropogenic activity on the chemical weathering process. This accounted for approximately 30% of the total SWR in the LRB. Our results demonstrate the effectiveness of hydrochemical source identification for quantifying the impacts of anthropogenic activity on chemical weathering. [ABSTRACT FROM AUTHOR]

A H2O mediated practical and highly regioselective chloro- and bromo-trifluoromethylthiolation of sulfur ylides is reported using a difunctionalization strategy. In the reaction sequence, sulfur ylides presumably react with an electrophilic trifluoromethylthiolating reagent to generate an α-SCF3 substituted sulfonium salt intermediate, which then undergoes a substitution with nucleophilic halogens. [ABSTRACT FROM AUTHOR]

Convenient strategies to transform regular liposomes or nano-micelles into multifunctional theranostics would be highly valuable in cancer therapy. Herein, we developed an amphiphilic fluorinated porphyrin dendrimer as a multifunctional "add-on" module which would self-assemble onto liposomal drug delivery systems and conveniently transform the liposomes into novel theranostics. Through cancer cells and murine xenograft tumor model assays, the theranostics showed valuable fluorescence/19F magnetic resonance dual modal imaging and highly efficient chemo-photodynamic therapy. The modular strategy facilitates the convenient and standardized preparation of multifunctional theranostics. [ABSTRACT FROM AUTHOR]

Herein, we developed fluorinated nanoemulsions with significantly enhanced in vitro and in vivo129Xe hyper-CEST MRI, 19F MRI and fluorescence imaging signals for selective and sensitive tumor detection and NIR-activated photodynamic therapy. [ABSTRACT FROM AUTHOR]

Light microscopy can offer certain advantages over electron microscopy in terms of acquiring detailed insights into the biological/intra-cellular milieu. In recent years, with the development of new fluorescence imaging technologies, it has become extremely important to assess the role of designing appropriate fluorophores in acquiring desired biological information without encountering any untoward hitches. Over the years, external fluorophores have been prevalently used in fluorescence microscopy and single-molecule fluorescence microscopy-based studies. Photostable fluorogenic probes with high extinction coefficients and quantum yields, exhibiting minimum autofluorescence and photobleaching properties, are preferred in single-molecule microscopy as they can tolerate long-term laser exposure. Therefore, the development of triplet state quenchers and/or any other suitable new strategy to ensure the photo-stability of the fluorophores during long-term live cell imaging exercises is highly anticipated. In this feature article, various strategies for stabilizing fluorophores, including the mechanisms of TSQ-induced stabilization, have been thoroughly reviewed considering contemporary literature reports and applications. [ABSTRACT FROM AUTHOR]

The microviscosity change associated with reticulophagy is an important component for studying endoplasmic reticulum (ER) stress disorders. Here, a BODIPY-arsenicate conjugate 1-based fluorescent molecular rotor was designed to covalently bind vicinal dithiol-containing proteins in the ER, exhibiting a bifunction of reticulophagy initiation and microviscosity evaluation. Therefore, we could quantify the local viscosity changes during reticulophagy based on the fluorescence lifetime changes of probe 1. [ABSTRACT FROM AUTHOR]

A convenient strategy was developed for highly branched and multifunctionalized peptidic monodisperse polyethylene glycol “brushes”, which exhibit remarkable physicochemical and biological properties and potential as versatile biomaterials. [ABSTRACT FROM AUTHOR]

As a promising cell tracking technology, 19F MRI suffers from low sensitivity. Here, fluorinated nanoemulsions with a unified 19F signal and paramagnetic relaxation enhancement were developed as 19F MRI cellular tracers with high stability, size controllability, biocompatibility, cellular uptake, and dual-modality for sensitive in vivo RAW264.7 cell tracking. [ABSTRACT FROM AUTHOR]

Tracking drugs with 19F MRI would be beneficial for developing theranostics and optimizing drug therapy. To this end, a fluorinated dendritic amphiphile with high 19F MRI sensitivity and biocompatibility has been developed for 19F MRI tracking of doxorubicin (DOX)-loaded liposomes in mice, which may provide an effective platform to in vivo trace various drugs with 19F MRI. [ABSTRACT FROM AUTHOR]

Optical Coherence Tomography (OCT) is a valuable technology that has been used to obtain microstructure images of tissue, and has several advantages, though its applications are limited in high-scattering tissues. Therefore, semiconducting polymer nanoparticles (SPNs) that possess strong absorption characteristics are applied to decrease light scattering in tissues and used as exogenous contrast agents for enhancing the contrast of OCT imaging detection. In this paper, we prepared two kinds of SPNs, termed PIDT-TBZ SPNs and PBDT-TBZ SPNs, as the contrast agents for OCT detection to enhance the signal. Firstly, we proved that they were good contrast agents for OCT imaging in agar–TiO2. After that, the contrast effects of these two SPNs were quantitatively analyzed, and then cerebral blood vessels were monitored by a home-made SD-OCT system. Finally, we created OCT images in vitro and in vivo with these two probes and performed quantitative analysis using the images. The results indicated that these SPNs created a clear contrast enhancement of small vessels in the OCT imaging process, which provides a basis for the application of SPNs as contrast agents for bioimaging studies. [ABSTRACT FROM AUTHOR]

Herein, we report rational design, synthesis, and application of a two-photon fluorescent probe (Tyro-1) for tracking intracellular tyrosinase activity. The chemoselective detection of tyrosinase is precluded from interference of other competitive omnipresent oxidizing entities in cellular milieu. The probe showed 12.5-fold fluorescence enhancement at λem = 450 nm in the presence of tyrosinase. The nontoxic probe Tyro-1 provides information about H2O2-mediated upregulation of tyrosinase through cellular imaging. Its two-photon imaging ability makes it a noninvasive tool for validating the expression of tyrosinase in the live cells. [ABSTRACT FROM AUTHOR]

Living organisms are generally composed of complex cellular processes which persist only within their native environments. To enhance our understanding of the biological processes lying within complex milieus, various techniques have been developed. Specifically, the emergence of super-resolution microscopy has generated a renaissance in cell biology by redefining the existing dogma towards nanoscale cell dynamics, single synaptic vesicles, and other complex bioprocesses by overcoming the diffraction-imposed resolution barrier that is associated with conventional microscopy techniques. Besides the typical technical reliance on the optical framework and computational algorithm, super-resolution imaging microscopy resorts largely to fluorescent materials with special photophysical properties, including fluorescent proteins, organic fluorophores and nanomaterials. In this tutorial review article, with the emphasis on cell biology, we summarize the recent developments in fluorescent materials being utilized in various super-resolution techniques with successful integration into bio-imaging applications. Fluorescent proteins (FP) applied in super-resolution microscopy will not be covered herein as it has already been well summarized; additionally, we demonstrate the breadth of opportunities offered from a future perspective. [ABSTRACT FROM AUTHOR]

Salinomycin is a promising anti-cancer agent which selectively targets cancer stem cells. To improve its potency and selectivity, an analog library of salinomycin was generated by site-specific modification and CuAAc derivatization. Through a cytotoxicity analysis of the library, a fluorinated analog with high potency, selectivity, and 19F MRI sensitivity was discovered as a novel theranostic agent. [ABSTRACT FROM AUTHOR]

A near-UV excited phosphor, Y4Si2O7N2:Ce3+, was synthesized using a solid-state reaction. The crystal structure and luminescence properties were studied. Y4Si2O7N2 crystallizes in a monoclinic unit cell with space group P21/c, lattice constants a = 7.5678(2) Å, b = 10.4529(1) Å, c = 10.7779(3) Å and β = 110.06°, and cell volume = 800.85(2) Å3. The crystal structure of Y4Si2O7N2, featuring Si(O,N)4 polyhedra, is provided, and there are four different Y3+ coordination environments with two different coordination numbers in the structure. Ce3+-doped Y4Si2O7N2 exhibited a broad emission band, and the maximum emission wavelength could be tuned from blue (λem = 450 nm) to green (λem = 515 nm) by increasing the concentration of Ce3+. The quantum efficiency was determined to be about 47%. The results show that Y4Si2O7N2:Ce3+ is a candidate for use as a conversion phosphor for near-UV white LED applications. [ABSTRACT FROM AUTHOR]

Pure nitride Ca-α-sialon phosphors with the composition Ca1.4−xAl2.8Si9.2N16:xEu (x = 0–0.3) were successfully prepared by gas-pressed sintering and their luminescence properties and morphology were investigated. Simultaneously, their time-resolved spectra were also presented. Ca1.4Al2.8Si9.2N16:Eu exhibited broad-band yellow-orange emission centered at ∼592 nm (FWHM ≈ 85 nm) under 400 nm excitation and with good thermal stability. Its emission intensity at 250 °C remained 88% of that measured at room temperature. The emission intensity was 1.7 times that of YAG:Ce3+ (P46-Y3) commercial phosphor. The outstanding luminescent properties allow it to be an attractive luminescent material for white LEDs. [ABSTRACT FROM AUTHOR]

Dual-imaging agents with highly sensitive fluorescence (FL) imaging and highly selective fluorine-19 magnetic resonance imaging ( 19 F MRI) are valuable for biomedical research. At the same time, photosensitizers with a high reactive oxygen species (ROS) generating capability are crucial for photodynamic therapy (PDT) of cancer. Herein, a series of tetra-trifluoromethylated aza-boron dipyrromethenes (aza-BODIPYs) were conveniently synthesized from readily available building blocks and their physicochemical properties, including ultraviolet-visible (UV-Vis) absorption, FL emission, photothermal efficacy, ROS generating efficacy, and 19 F MRI sensitivity, were systematically investigated. An aza-BODIPY with 12 symmetrical fluorines was identified as a potent FL- 19 F MRI dual-imaging traceable photodynamic agent. It was found that the selective introduction of trifluoromethyl (CF 3 ) groups into aza-BODIPYs may considerably improve their UV absorption, FL emission, photothermal efficacy, and ROS generating properties, which lays the foundation for the rational design of trifluoromethylated aza-BODIPYs in biomedical applications.

The synergistic chemotherapy and photodynamic therapy (PDT) may significantly improve the cancer therapeutic efficacy, in which fluorinated nanoemulsions are highly advantageous for their ability to deliver oxygen to hypoxic tumors and provide fluorine-19 magnetic resonance imaging ( 19 F MRI). The low solubility of chemotherapy drugs and photosensitizers in current perfluorocarbon (PFC)-based 19 F MRI agents usually leads to complicated formulations or chemical modifications and low nanoemulsion stability and performance. Herein, we employ readily available partially fluorinated ethyl 2-(3,5-bis(trifluoromethyl)phenyl)acetate as the 19 F MRI agent and the solvent to dissolve the cancer stem cell inhibitor salinomycin and the photosensitizer ICG for the convenient preparation of 19 F MRI-fluorescence dual imaging and synergistic chemotherapy, photothermal and photodynamic therapy nanoemulsions. The chemotherapy drug salinomycin has a high solubility in the partially fluorinated reagent, facilitating its high loading and efficient delivery. Paramagnetic iron(III) (Fe 3+ ) is incorporated into the nanoemulsion through the dissolved chelator to significantly improve the 19 F MRI sensitivity. Furthermore, the dissolved fluorinated 2-pyridone enables the efficient capture and sustained release of singlet oxygen in the dark for high PDT efficacy. The multifunctional nanoemulsions show sensitive 19 F MRI and fluorescence dual imaging capability and high synergistic chemotherapy, photothermal and photodynamic therapy efficacy in cancer cells, which may be valuable oxygen delivery, sustained ROS generating and release, dual imaging and multimodal therapy agents for hypoxic tumors. This study provided a convenient co-solubilization strategy for the rapid construction of multifunctional theranostics for hypoxic tumors.

As a promising cell tracking technology, 19F MRI suffers from low sensitivity. Here, fluorinated nanoemulsions with a unified 19F signal and paramagnetic relaxation enhancement were developed as 19F MRI cellular tracers with high stability, size controllability, biocompatibility, cellular uptake, and dual-modality for sensitive in vivo RAW264.7 cell tracking.

Tracking drugs with 19F MRI would be beneficial for developing theranostics and optimizing drug therapy. To this end, a fluorinated dendritic amphiphile with high 19F MRI sensitivity and biocompatibility has been developed for 19F MRI tracking of doxorubicin (DOX)-loaded liposomes in mice, which may provide an effective platform to in vivo trace various drugs with 19F MRI.

For detecting metal ions with 19 F chemical exchange saturation transfer magnetic resonance imaging ( 19 F CEST MRI), a class of novel fluorinated chelators with diverse fluorine contents and chelation properties were conveniently synthesized on gram scales. Among them, a DTPA-derived chelator with high sensitivity and selectivity was identified as a novel 19 F CEST imaging probe for simultaneously detecting multiple metal ions.

Fluorine is a highly attractive element for both medicinal chemistry and imaging technologies. To facilitate protein tyrosine phosphatases (PTPs)-targeted drug discovery and imaging-guided PTP research with fluorine, several highly potent and 19 F MR sensitive PTP inhibitors were discovered through a structure-based focused library strategy.

Correction for 'Discovery of a (19)F MRI sensitive salinomycin derivative with high cytotoxicity towards cancer cells' by Qiuyan Shi et al., Chem. Commun., 2016, 52, 5136-5139.

Salinomycin is a promising anti-cancer agent which selectively targets cancer stem cells. To improve its potency and selectivity, an analog library of salinomycin was generated by site-specific modification and CuAAc derivatization. Through a cytotoxicity analysis of the library, a fluorinated analog with high potency, selectivity, and (19)F MRI sensitivity was discovered as a novel theranostic agent.

Rhodamine-labelled dieckol (1) synthesized through a click reaction was found to be localized in the endoplasmic reticulum (ER) of RAW 264.7 cells. Anti-inflammatory activity of compound was considerably greater than that of dieckol itself.

We herein report a fluorescent bimodal probe (1) capable of determining ER viscosity and polarity changes using FLIM and fluorescence ratiometry, respectively; during ER stress caused by tunicamycin, the viscosity was increased from ca. 129.5 to 182.0 cP and the polarity of the ER (dielectric constant, ε) enhanced from 18.5 to 21.1.

A specific ratiometric nanoprobe for hypochlorite was constructed as a paradigm of FRET spectral unmixing. The separation of FRET pairs' emissions reaches 175 nm, which ensures that the FRET probing is more accurate. This new nanoprobe shows high selectivity and potential in biological systems.

A series of Ru(bpy)(3)(2+)-(CH(2))(n)-MV(2+) complexes (, n = 3, 4, 7) used for DNA photocleavage have been designed and synthesized. Under the irradiation of visible light, complexes can cleave supercoiled plasmid DNA (pBR322) both in air and under Ar atmosphere. Radical species such as O(2)(-) , OH and the light-induced charge-separated (CS) oxidation state Ru(bpy)(3)(3+)-(CH(2))(n)-MV(+) are responsible for the cleavage. The longer the carbon chain linkage, the higher the DNA photocleavage efficiency. It is noted that backwards intramolecular electron transfer (ET) that exist in complexes can lead to some decreasing effect on the cleavage result, while inclusion of complexes with cucurbit[8]uril (CB[8]) inhibits the backwards ET to some extent, thereby increasing photocleavage efficiency.

Organocatalysts containing primary-secondary diamines based on bispidine have been developed to catalyze the asymmetric Michael addition of ketones to alkylidene malonates and nitroalkenes. The corresponding products were obtained in high yields (up to 99%) with high diastereoselectivities (up to 99:1) and high enantioselectivities (up to 97% ee) under mild conditions using either environmentally benign water as the solvent or no solvent.