Reversible Thermochromism of Aggregation-Induced Emission-Active Benzophenone Azine Based on Polymorph-Dependent Excited-State Intramolecular Proton Transfer Fluorescence

In this work, (2-hydroxy-4-methoxyphenyl)­(phenyl)­methanone azine (<b>1</b>) was found to exhibit aggregation-induced emission (AIE) and tunable solid fluorescence upon alternate annealing/melting treatments. According to the characterizations by X-ray crystallography, X-ray powder diffraction, and differential scanning calorimetry, the switching between the two different polymorphs was responsible for the tunable solid fluorescence as a consequence of polymorph-dependent excited-state intramolecular proton transfer (ESIPT) fluorescence, while the thermochromism was contributed by the conformational flexibility of rotary phenyl rings. The change in the tightness of packing upon annealing or melting thermal treatments resulted in the emission at different wavelengths. Therefore, polymorph-dependent ESIPT fluorescence could be utilized as a new strategy to develop efficient AIE-active materials in response to external stimuli

Reversible Thermochromism of Aggregation-Induced Emission-Active Benzophenone Azine Based on Polymorph-Dependent Excited-State Intramolecular Proton Transfer Fluorescence

In this work, (2-hydroxy-4-methoxyphenyl)­(phenyl)­methanone azine (<b>1</b>) was found to exhibit aggregation-induced emission (AIE) and tunable solid fluorescence upon alternate annealing/melting treatments. According to the characterizations by X-ray crystallography, X-ray powder diffraction, and differential scanning calorimetry, the switching between the two different polymorphs was responsible for the tunable solid fluorescence as a consequence of polymorph-dependent excited-state intramolecular proton transfer (ESIPT) fluorescence, while the thermochromism was contributed by the conformational flexibility of rotary phenyl rings. The change in the tightness of packing upon annealing or melting thermal treatments resulted in the emission at different wavelengths. Therefore, polymorph-dependent ESIPT fluorescence could be utilized as a new strategy to develop efficient AIE-active materials in response to external stimuli

Reversible Thermochromism of Aggregation-Induced Emission-Active Benzophenone Azine Based on Polymorph-Dependent Excited-State Intramolecular Proton Transfer Fluorescence

In this work, (2-hydroxy-4-methoxyphenyl)­(phenyl)­methanone azine (<b>1</b>) was found to exhibit aggregation-induced emission (AIE) and tunable solid fluorescence upon alternate annealing/melting treatments. According to the characterizations by X-ray crystallography, X-ray powder diffraction, and differential scanning calorimetry, the switching between the two different polymorphs was responsible for the tunable solid fluorescence as a consequence of polymorph-dependent excited-state intramolecular proton transfer (ESIPT) fluorescence, while the thermochromism was contributed by the conformational flexibility of rotary phenyl rings. The change in the tightness of packing upon annealing or melting thermal treatments resulted in the emission at different wavelengths. Therefore, polymorph-dependent ESIPT fluorescence could be utilized as a new strategy to develop efficient AIE-active materials in response to external stimuli

Green and Simple Extraction of Arsenic Species from Rice Flour Using a Novel Ultrasound-Assisted Enzymatic Hydrolysis Method

It is well established that arsenic (As) has many toxic compounds, and in particular, inorganic As (iAs) has been classified as a type-1 carcinogen. The measuring of As species in rice flour is of great importance since rice is a staple of the diet in many countries and a major contributor to As intake in the Asian diet. In this study, several solvents and techniques for the extraction of As species from rice flour samples prior to their analysis by HPLC-ICP-MS were investigated. The extraction methods were examined for their efficiency in extracting various arsenicals from a rice flour certified reference material, NMIJ-7532a, produced by the National Metrology Institute of Japan. Results show that ultrasound-assisted extraction at 60 &deg;C for 1 h and then heating at 100 &deg;C for 2.5 h in the oven using a thermostable &alpha;-amylase aqueous solution was highly effective in liberating the arsenic species. The recoveries of iAs and dimethylarsinic acid (DMA) in NMIJ-7532a were 99.7% &plusmn; 1.6% (n = 3) and 98.1% &plusmn; 2.3% (n = 3), respectively, in comparison with the certificated values. Thus, the proposed extraction method is a green procedure that does not use any acidic, basic, or organic solvents. Moreover, this extraction method could effectively maintain the integrity of the native arsenic species of As(III), As(V), monomethylarsonate (MMA), DMA, arsenobetaine (AsB) and arsenocholine (AsC). Under the optimum extraction, chromatography and ICP-MS conditions, the limits of detection (LOD) obtained were 0.47 ng g&minus;1, 1.67 ng g&minus;1 and 0.80 ng g&minus;1 for As(III), As(V) and DMA, respectively, while the limits of quantification (LOQ) achieved were 1.51 ng g&minus;1, 5.34 ng g&minus;1 and 2.57 ng g&minus;1 for As(III), As(V) and DMA, respectively. Subsequently, the proposed method was successfully applied to As speciation analysis for several rice flour samples collected from contaminated areas in China

Green and Simple Extraction of Arsenic Species from Rice Flour Using a Novel Ultrasound-Assisted Enzymatic Hydrolysis Method

It is well established that arsenic (As) has many toxic compounds, and in particular, inorganic As (iAs) has been classified as a type-1 carcinogen. The measuring of As species in rice flour is of great importance since rice is a staple of the diet in many countries and a major contributor to As intake in the Asian diet. In this study, several solvents and techniques for the extraction of As species from rice flour samples prior to their analysis by HPLC-ICP-MS were investigated. The extraction methods were examined for their efficiency in extracting various arsenicals from a rice flour certified reference material, NMIJ-7532a, produced by the National Metrology Institute of Japan. Results show that ultrasound-assisted extraction at 60 °C for 1 h and then heating at 100 °C for 2.5 h in the oven using a thermostable α-amylase aqueous solution was highly effective in liberating the arsenic species. The recoveries of iAs and dimethylarsinic acid (DMA) in NMIJ-7532a were 99.7% ± 1.6% (n = 3) and 98.1% ± 2.3% (n = 3), respectively, in comparison with the certificated values. Thus, the proposed extraction method is a green procedure that does not use any acidic, basic, or organic solvents. Moreover, this extraction method could effectively maintain the integrity of the native arsenic species of As(III), As(V), monomethylarsonate (MMA), DMA, arsenobetaine (AsB) and arsenocholine (AsC). Under the optimum extraction, chromatography and ICP-MS conditions, the limits of detection (LOD) obtained were 0.47 ng g−1, 1.67 ng g−1 and 0.80 ng g−1 for As(III), As(V) and DMA, respectively, while the limits of quantification (LOQ) achieved were 1.51 ng g−1, 5.34 ng g−1 and 2.57 ng g−1 for As(III), As(V) and DMA, respectively. Subsequently, the proposed method was successfully applied to As speciation analysis for several rice flour samples collected from contaminated areas in China

Aggregation-Induced Emission Luminogen-Embedded Silica Nanoparticles Containing DNA Aptamers for Targeted Cell Imaging

Conventional fluorophores usually undergo aggregation-caused quenching (ACQ), which limits the loading amount of these fluorophores in nanoparticles for bright fluorescence imaging. On the contrary, fluorophores with aggregation-induced emission (AIE) characteristics are strongly fluorescent in their aggregate states and have been an ideal platform for developing highly fluorescent nanomaterials, such as fluorescent silica nanoparticles (FSNPs). In this work, AIE luminogens based on salicylaldehyde hydrazones were embedded in silica nanoparticles through a facile noncovalent approach, which afforded AIE-FSNPs emitting much brighter fluorescence than that of some commercial fluorescein-doped silica and polystyrene nanoparticles. These AIE-FSNPs displaying multiple fluorescence colors were fabricated by a general method, and they underwent much less fluorescence variation due to environmental pH changes compared with fluorescein-hybridized FSNPs. In addition, a DNA aptamer specific to nucleolin was functionalized on the surface of AIE-FSNPs for targeted cell imaging. Fluorescent microscopy and flow cytometry studies both revealed highly selective fluorescence staining of MCF-7 (a cancer cell line with nucleolin overexpression) over MCF-10A (normal) cells by the aptamer-functionalized AIE-FSNPs. The fluorescence imaging in different color channels was achieved using AIE-FSNPs containing each of the AIE luminogens, as well as photoactivatable fluorescent imaging of target cells by the caged AIE fluorophore

CCQM-K145: Toxic and essential elements in bovine liver Final Report

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. Also, working with other systems and organs, it is responsible for several important functions such as storing iron, detoxifying harmful substances, maintaining the hormonal balance, and producing immune factors to fight infections. Cattle seemed to be the most sensitive animal species with respect to some metal toxicities resulting from ingestion of feed material. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. Therefore, the IAWG has included the need for such a key comparison to maintain, expand and improve core capabilities, and to support specific CMCs claim in bio-sample analysis as well

Label-Free Catalytic and Molecular Beacon Containing an Abasic Site for Sensitive Fluorescent Detection of Small Inorganic and Organic Molecules

In this work, two methods with complementary features, catalytic and molecular beacon (CAMB) and label-free fluorescent sensors using an abasic site, have been combined into new label-free CAMB sensors that possess advantages of each method. The label-free method using a dSpacer-containing molecular beacon makes CAMB more cost-effective and less interfering with the catalytic activity, while CAMB allows the label-free method to use true catalytic turnovers for signal amplifications, resulting in a new label-free CAMB sensor for Pb²⁺ ion, with a detection limit of 3.8 nM while maintaining the same selectivity. Furthermore, by using CAMB to overcome the label-free method’s limitation of requiring excess enzyme strands, a new label-free CAMB sensor using aptazyme is also designed to detect adenosine down to 1.4 μM, with excellent selectivity over other nucleosides