A Ratio Fluorescence Method Based on Dual Emissive Copper Nanoclusters for the Detection of Vanillin.

In this study, a novel double-emission fluorescence probe at 340 and 400 nm was synthesized by one-pot method using phenylalanine (Phe) and ascorbic acid (AA) as stabilizing and reducing agents. It was found that the fluorescence intensity of the probe at 400 nm could be controlled by controlling the temperature within a certain range, and the ratio of double-emission fluorescence probe could be further regulated. Under the optimal conditions, the fluorescence intensity at 340 nm decreased significantly, while it only showed a slight decrease at 400 nm, which constituted the ratio fluorescence probe. The synthesized fluorescence probe showed good linearity in the range of 0.2-32 µM, and its detection limit was 63.4 nM. Moreover, the method was successfully employed to determine VA in vanilla drink and perfumes, and corresponding results were consistent with those of HPLC.

Side chain of confined xylan affects cellulose integrity leading to bending stem with reduced mechanical strength in ornamental plants.

The stem support for fresh-cut flowers exerts a profound influence on the display of their blossoms. During vase insertion, bending stems significantly affect the ornamental value, but much remains unclear about the underlying reasons. In this study, six pairs of ornamental plants were screened for the contrast of bending and straight stems. The bending stems have weakened mechanical force and biomass recalcitrance compared with the straight ones. Meanwhile, cells in the bending stems became more loosely packed, along with a decrease in cell wall thickness and cellulose levels. Furthermore, wall properties characterizations show bending stems have decreased lignocellulosic CrI and cellulose DP, and enhanced the branching ratio of hemicellulose which is trapped in the cellulose. Given the distinct cell wall factors in different species, all data are grouped in standardized to eliminate the variations among plant species. The principal composition analysis and correlation analysis of the processed dataset strongly suggest that cellulose association factors determine the stem mechanical force and recalcitrance. Based on our results, we propose a model for how branches of confined hemicellulose interacted with cellulose to modulate stem strength support for the straight or bending phenotype in cut flowers.

Sensitive Detections of Sodium Dichloroisocyanurate and Rosmarinic Acid by Polyvinylpyrrolidone Coated Copper Nanoclusters.

In this article, the water-soluble blue-light-emitting copper nanoclusters (CuNCs) were prepared by polyvinylpyrrolidone (PVP) and ascorbic acid as templating and reducing agents, respectively. The optimization of synthesis conditions of PVP-CuNCs were studied and analyzed. And the quantum yield of the PVP-CuNCs was calculated to be 14.97%. It had good specificity and exceptionally sensitive detection for sodium dichloroisocyanurate (DCCNa)/rosmarinic acid (RA), with a linear response range of 0.030-2.400/0.030-0.900 µM and corresponding LOD value of 10.766/8.985 nM. Moreover, the fluorescent reaction mechanisms of the PVP-CuNCs-DCCNa and PVP-CuNCs-DCCNa-RA systems were discussed, and the sensing probe could be effectively used for the assays of DCCNa and RA in genuine samples, whose results were acceptable.

Silicon Doped Carbon Dots as an New Ratiometric Fluorescence Probe for Proanthocyanidins Assay Based on the Redox Reaction Between Cr(VI) and Proanthocyanidins.

In the study, silicon doped carbon quantum dots (Si-CQDs) was prepared by one-pot hydrothermal method with (3-aminopropyl) triethoxysilane (APTES) and o-phenylenediamine (OPD) as raw materials. Then a new ratiometric fluorescent probe (RF-probe) was successfully established for sensitively and selectively monitoring proanthocyanidins (PAs) with a linear range of 10-500 nM and limit of detection (LOD) of 5.6 nM. that is, the fluorescence (FL) intensity of Si-CQDs at 570 nm was used as the built-in reference, while dopamine (DA) reacting with 4-hexylresorcinol (4-HR) could produce a new fluorescent substance (named as azamonardine, AZMON), and its FL intensity at 480 nm was reduced because Cr(VI) could oxidize DA to generate quinone without fluorescence. In the presence of PAs, Cr(VI) was reduced to Cr(III), which caused that the amount of DA reacting with 4-HR was increased, thus the FL intensity of AZMON was recovered. Furthermore, the RF-probe was successfully used for the determination of PAs in black goji berry from two different areas and PAs capsule with satisfactory results compared to the standard HPLC method.