Taming Janus-Faced Quinoline-Derived Fluorescent Probes for Dual-Channel Distinguishable Visualization of HSO3- and HClO in Dried Foods and Living Cells.

With the booming development of food manufacturing, developing ideal analytical tools to precisely quantify food additives is highly sought after in the food science field. Herein, a new series of quinoline-derived multifunctional fluorescent probes has been synthesized. Bearing double reactive sites, these compounds display fluorescence response toward both bisulfite (HSO3-) and hypochlorous acid (HClO). Among these compact structures, compound ethyl-2-cyano-3-(6-(methylthio)quinolin-2-yl)acrylate (QTE) was screened out. Probe QTE not only shows ratiometric variation toward HSO3- with little cross talk but also performs turn-off signal toward HClO. In addition, probe QTE has been utilized for bioimaging of HClO in living cells. Furthermore, the HSO3- content in dried food samples has been appraised by QTE with satisfactory results. Meanwhile, relying on the apparent chromaticity change, a flexible dark-box device has been elaborated for chromatic analysis, promoting visualization of HSO3- in the field.

Cascade reaction-based highly sensitive fluorescent sensing systems applicable for dual-pattern fluorescence visualizing of thiophenol flavors in meat products and condiments.

Thiophenols (ArSHs) are widely used as popular flavoring ingredients for making daily dishes. Dissecting the ArSHs contents in common foodstuffs is meaningful in the field of food safety science. Herein, a novel small-molecule sensor 2-(1H-benzo[d]imidazol-2-yl)-3-(2-(2,4-dinitrophenoxy)-4-morpholinophenyl)acrylonitrile (NOSA) has been tailored. The NOSA is able to respond to ArSHs, spontaneously yielding highly green-emissive fluorescent iminocoumarin (I500). This cascade reaction-based strategy is sensitive (limit-of-detection = 2.8 nM), rapid (within 5 min), and selective toward ArSH flavors. Probe NOSA has been applied to the determination of ArSHs in real-life meat products and condiments. Moreover, a far-red fluorescent compound, 2-(7-(diethylamino)-4-(4-(methylthio)styryl)-2H-chromen-2-ylidene)malononitrile (CMMT), has been first combined with NOSA to construct a composite probe NOSA@CMMT for the ratiometric detection of ArSHs (I500/I630). System NOSA@CMMT exhibits a conspicuous fluorescence change from deep-red to light-green. Benefitted from the gorgeous chromatic fluctuation, a smartphone-integrated analysis platform is established for the real-time evaluation of ArSHs level.

Gires-Tournois Immunoassay Platform for Label-Free Bright-Field Imaging and Facile Quantification of Bioparticles.

Bright-field imaging of nanoscale bioparticles is a challenging task for optical microscopy because the light-matter interactions of bioparticles are weak on conventional surfaces due to their low refractive index and small size. Alternatively, advanced imaging techniques, including near-field microscopy and phase microscopy, have enabled visualization and quantification of the bioparticles, but they require assistance of sophisticated/customized systems and post-processing with complex established algorithms. Here, a simple and fast immunoassay device, Gires-Tournois immunoassay platform (GTIP) is presented, which provides unique color dynamics in response to optical environment changes and thus enables the label-free bright-field imaging and facile quantification of bioparticles using conventional optical microscopy. Bioparticles on GTIP slow down the velocity of reflected light, leading to vivid color change according to the local particle density and maximizing chromatic contrast for high spatial distinguishability. The particle distribution and density on the surface of the resonator are readily analyzed through 2D raster-scanning-based chromaticity analysis. GTIP offers multiscale sensing capability for target analytes that possess different refractive indices and sizes.

6LiF:ZnS(Ag) Neutron Detector Performance Optimized Using Waveform Recordings and ROC Curves.

We used Gaussian separation and receiver operating characteristic (ROC) curves to optimize the neutron sensitivity and gamma rejection of an ultra-thin 6LiF:ZnS(Ag)-scintillator-based neutron detector paired with a silicon photomultiplier (SiPM). We recorded the waveforms while operating the detector in a monochromatic cold neutron beam and in the presence of isotopic 137Cs and 60Co gamma sources. We used a two-window charge comparison (CC) pulse-shape discrimination (PSD) technique to distinguish the neutron capture events from other types of signals. By feeding the recorded waveforms through variants of this algorithm, it was possible to optimize the duration of the integration windows [(0-100 ns) for the prompt window and (100-2300 ns)] for the delayed window. We then computed the detector's ROC curve from waveform recordings and compared that with the experimental performance. We also used this procedure to compare a series of detector configurations to select the optimal bias voltage for the SiPM photosensor.

Synthetic pigments for Japanese quail fed diets with sorghum / Pigmentantes sintéticos para codornas japonesas alimentadas com rações à base de sorgo

Corn is the major energy ingredient in diets, and many ingredients have been tested aiming to replace it. In this regard, sorghum stands out for its chemical profile similar to that of corn. However, because it is low in carotenoids, its inclusion in diets reduces the egg yolk color pigmentation, which can be corrected by the addition of synthetic pigments. This study aimed to evaluate the performance and egg quality of Japanese quail (Coturnix japonica) supplemented with red (canthaxanthin) and yellow (apo-ester 10%) synthetic pigments. A total of 150 quail at 70 days of age were distributed according to the experimental diet [R1: corn-based control diet (DC); R2: sorghum-based diet (DS); R3: DS + yellow; R4: DS + yellow + red; and R5: DS + red] with six replications and five birds per experimental unit, for 28 days. Performance, egg quality, yolk color, and feed cost characteristics were evaluated. Regression equations were estimated for the effects of color as a function of periods, and treatment means were compared by Tukey's test at 0.05 probability. There was no significant effect (P>0.05) of additives on the quail productive traits. However, addition of synthetic pigments significantly improved the chromatic profile of the yolks (P<0.05). Inclusion of synthetic pigments improves yolk color, but should be evaluated according to market demands.(AU)

O milho é o principal ingrediente energético nas rações. A fim de substituí-lo, vários ingredientes foram testados. Nesse sentido, destaca-se o sorgo, pois apresenta perfil bromatológico semelhante ao do milho. No entanto, por ser deficiente em carotenoides, sua inclusão na ração reduz a pigmentação da gema do ovo, o que pode ser corrigido por meio da adição de pigmentos sintéticos. Objetivou-se, com este estudo, avaliar o desempenho zootécnico e a qualidade dos ovos de codornas japonesas (Coturnix japonica) suplementadas com os pigmentantes sintéticos vermelho (cantaxantina) e amarelo (apoéster 10%). Foram utilizadas 150 codornas japonesas com 70 dias de idade, distribuídas de acordo com a ração experimental (R1: ração referência à base de milho; R2: ração à base de sorgo (RS); R3: RS + amarelo; R4: RS + amarelo + vermelho; R5: RS + vermelho), com seis repetições e cinco aves por unidade experimental, durante 28 dias. Foram avaliadas as características de desempenho, qualidade dos ovos, cor da gema e custo das rações. Equações de regressão dos efeitos da cor em função dos períodos foram estimadas, e as médias de tratamento foram comparadas pelo teste de Tukey com 0,05 de probabilidade. Não houve efeito significativo (P>0,05) dos aditivos sobre as características produtivas das codornas. Entretanto, a adição de pigmentantes sintéticos melhorou significativamente o perfil cromático das gemas dos ovos de codornas (P<0,05). A inclusão de pigmentantes sintéticos melhora a cor das gemas, porém deve ser avaliada de acordo com as exigências de mercado.(AU)

Chromatic analysis by monitoring unmodified silver nanoparticles reduction on double layer microfluidic paper-based analytical devices for selective and sensitive determination of mercury(II).

This study demonstrates chromatic analysis based on a simple red green blue (RGB) color model for sensitive and selective determination of mercury(II). The analysis was performed by monitoring the color change of a microfluidic Paper-based Analytical Device (µPAD). The device was fabricated by using alkyl ketene dimer (AKD)-inkjet printing and doped with unmodified silver nanoparticles (AgNPs) which were disintegrated when being exposed to mercury(II). The color intensity was detected by using an apparatus consisting of a digital camera and a homemade light box generating constant light intensity. A progressive increase in color intensity of the tested area on the µPAD (3.0mm) was observed with increasing mercury(II) concentration. The developed system enabled quantification of mercury(II) at low concentration with the detection limit of 0.001mgL(-1) (3 SD blank/slope of the calibration curve) and small sample volume uptake (2µL). The linearity range of the calibration curve in this technique was demonstrated from 0.05 to 7mgL(-1) (r(2)=0.998) with good precision (RSD less than 4.1%). Greater selectivity towards mercury(II) compared with potential interference ions was also observed. Furthermore, the percentage recoveries of spiked water samples were in an acceptable range which was in agreement with the values obtained from the conventional method utilizing cold vapor atomic absorption spectrometer (CVAAS). The proposed technique allows a rapid, simple, sensitive and selective analysis of trace mercury(II) in water samples.

Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction.

Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. Microtox(®), rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation requirements and the simplicity of the bioassay open the possibility of in-situ water toxicity assessment with a fast and low-cost protocol.

Evolution of gold nanoparticle clusters in living cells studied by sectional dark-field optical microscopy and chromatic analysis.

The evolution of gold nanoparticle (Au NP) clusters in living cells are studied by using sectional dark-field optical microscopy and chromatic analysis approach. During endocytosis, Au NP clusters undergo fantastic color changes, from green to yellow-orange due to the plasmonic coupling effect. Analysis of brightness/hue values of the dark-field images helps estimate the numbers of Au NPs in the clusters. The Au NP clusters were further categorized into four groups within the endocytosis. As the results, the late endosomes had increased number of large Au NP clusters with time, while clustered numbers in secondary and tertiary groups were first increased and then decreased due to the fusion and fission of the endocytic vesicles. The time constants and cluster numbers for different groups are fitted by using an integrated rate equation, and show a positive correlation with the size of the Au NP cluster. The efficiency of Au NP uptake is only about 50% for normal cells, while 75% for cancer cells. Compared to normal cells, cancer cells show a larger number in uptake, while faster rate in removal. The propose method helps the kinetic study of endocytosed nanoparticles in physiological conditions.