Ba 1.8−x Sr x SiO 4 :0.1Ce 3+ ,0.1Na + (x = 0−1.8) phosphors were prepared by a high-temperature solid-state reaction. The emission peaks of Ba 1.8−x Sr x SiO 4 :0.1Ce 3+ ,0.1Na + shift from 391 to 411 nm with increasing Sr 2+ content under excitation by a UV light at around 360 nm. Ba 0.4 Sr 1.4 SiO 4 :0.1Ce 3+ ,0.1Na + phosphor exhibits the best performance of luminescence, whose absolute quantum efficiency is 97.2%, and the emission intensity at 150 °C remains 90% of that at room temperature. The effect of replacing Ba 2+ by Sr 2+ on the red shift of the emission band and the increase of quantum efficiency (QE) and thermal stability (TS) was investigated in detail based on the Rietveld refinements, Raman spectra, thermoluminescence, and decay curves, etc. The performance of UV chip-based pc-LEDs indicates that Ba 0.4 Sr 1.4 SiO 4 :0.1Ce 3+ ,0.1Na + can be a promising blue phosphor for white-emitting pc-LEDs.

In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors.

A novel acetylcholinesterase (AChE) liquid crystal (LC) biosensor based on enzymatic growth of gold nanoparticles (Au NPs) has been developed for amplified detection of acetylcholine (ACh) and AChE inhibitor. In this method, AChE mediates the hydrolysis of acetylthiocholine (ATCl) to form thiocholine, and the latter further reduces AuCl(4)(-) to Au NPs without Au nanoseeds. This process, termed biometallization, leads to a great enhancement in the optical signal of the LC biosensor due to the large size of Au NPs, which can greatly disrupt the orientational arrangement of LCs. On the other hand, the hydrolysis of ATCl is inhibited in the presence of ACh or organophosphate pesticides (OPs, a AChE inhibitor), which will decrease the catalytic growth of Au NPs and, as a result, reduce the orientational response of LCs. On the basis of such an inhibition mechanism, the AChE LC biosensor can be used as an effective way to realize the detection of ACh and AChE inhibitors. The results showed that the AChE LC biosensor was highly sensitive to ACh with a detection limit of 15 μmol/L and OPs with a detection limit of 0.3 nmol/L. This study provides a simple and sensitive AChE LC biosensing approach and offers effective signal enhanced strategies for the development of enzyme LC biosensors.

Uranyl ion (UO 2 2+) pollution is a serious environmental problem, and developing novel adsorption materials is essential for UO 2 2+ monitoring and removal. Although some progress is achieved, it is still a challenging task to develop an adsorption material with indicating signal for real-time evaluation of the adsorption degree and the UO 2 2+ concentration. Herein, this paper describes a smart photonic crystal hydrogel (PCH) material, which not only can be used for real-time monitoring function but also can be utilized for UO 2 2+ removal based on the chelation of UO 2 2+ with ligand groups in PCH material. The working principle is based on the binding of a uranyl ion to multiple ligand groups, which results in the shrinkage of PCH material and triggers a blue-shift of diffraction wavelength. Consequently, the adsorption degree and the UO 2 2+ concentration can be sensitively evaluated by measuring the diffraction shift or observing the color change with naked eye. With this PCH material, the lowest detectable concentration for UO 2 2+ is 10 × 10 −9 m, and the maximum adsorption capacity at 298 K is 169.67 mmol kg −1 . In addition, this material also holds good selectivity and regeneration feature, and shows desirable performance for UO 2 2+ analysis in real water samples.

Developing photocatalysts to steer conversion of solar energy toward high-value-added fine chemicals represents a potentially viable approach to address the energy crisis and environmental issues. However, enablement of this conversion is usually impeded by the sluggish kinetic process for proton-coupled electron transfer and rapid recombination of photogenerated excitons. Herein, we report a simple and general structural expansion strategy to facilitate charge transfer in conjugated microporous polymers (CMPs) via engineering the donor surrounding the trifluoromethylphenyl core. The resulting CMPs combine high surface area, strong light-harvesting capabilities, and tunable optical properties endowed by extended π-conjugation; the optimized compound CbzCMP-5 generated from 9,9′,9″-(2-(trifluoromethyl)benzene-1,3,5-triyl)tris(9H-carbazole) remarkably enhanced the photogenerated carrier transfer efficiency, enabling the functionalization of thiophenols toward thiocarbamates and 3sulfenylindoles with high photocatalytic efficiency. Most importantly, the in-depth insights into the carrier-transfer processes open up new prospects on further optimization and rational design of photoactive polymers for efficient charge-transfer-mediated reactions.

A novel fluorometric assay method based on target-induced signal on was developed for acetylcholinesterase (AChE) inhibitor with obviously improved detection sensitivity. In this method, the AChE molecules catalyzed the hydrolysis of acetylthiocholine (ATCl) to form thiocholine, which in turn can specifically react with fluorescent squaraine derivative, a specific chemodosimeter for thiol-containing compounds, resulting in fluorescence quenching and offering a low fluorometric background for the further detection of AChE inhibitor. In the presence of AChE inhibitor, the catalytic hydrolysis of ATCl is blocked, and then the squaraine derivative remains intact and shows signal-on fluorescence. The amount of the remaining fluorescent squaraine derivative is positively correlated with that of the AChE inhibitor in solution. This new designed sensing system shows an obviously improved sensitivity toward target with a detection limit of 5 pg mL(-1) (0.018 nM) for the AChE inhibitor, comparing favorably with previously reported fluorometric methods. To our best knowledge, this new method is the first example of fluorometric enzymatic assay for AChE inhibitors based on such a signal-on principle and using a specific reaction, which has potential to offer an effective strategy for the detection of AChE inhibitors.

Highly efficient and stable white emission is realized in a single-doped K2Ca(PO4)F:Eu2+ phosphor with Eu2+ on both K+ and Ca2+ sites.

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