ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2019
·Vol. 411
·期 25
·6677-6686
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IF 3.286
Tian Sizhu,Li Xuwen,Jiang Jia,Wang Kun,Zhang Hanqi,Yu Aimin,Zhang Ziwei
The antioxidant capacity of 22 kinds of fruits was measured by the developed electron spin resonance (ESR) method based on Cu 2+ sensor. Cu 2+ is reduced to Cu + by the antioxidants in the fruits, and the remaining Cu 2+ was determined by ESR and UV-Vis spectroscopy. Cu 2+ can give an ESR signal whereas Cu + cannot, and the loss of the ESR signal was used to quantify the antioxidant capacity of various fruits. The results were shown as vitamin C equivalent antioxidant capacity (VCEAC). The VCEAC values obtained by ESR and UV-Vis methods ranged from 24.23 to 688.61 mg/100 g and from 24.12 to 677.79 mg/100 g, respectively. Cupric ion reducing antioxidant capacity (CUPRAC) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) methods were employed for comparison. Based on Pearson’s correlation test, the results obtained by CUPRAC and DPPH methods were both significantly correlated with these obtained by the present method, which indicated that the novel method was reliable. Total phenolic content for all kinds of fruits was measured with the Folin–Ciocalteu reagent, and VCEAC values obtained by the ESR method were significantly correlated with total phenolic contents.
Graphical abstract
研究领域:
分析化学
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食品科学
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营养学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Additive Manufacturing
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2023
·
IF 11
Zhengqiang Guo,Hongrui Zhang,Weigui Xie,Aimin Tang,Wangyu Liu
Due to the constraints of photoinitiators and mechanical properties, vat photopolymerization 3D printable hydrogels are still the focus of current research. Drawing inspiration from the water-soluble modification of the photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), a rapid and expedient UV-curable hydrogel with remarkable strength and toughness has been developed using polymerizable micelles . The incorporation of polymerizable micelles not only significantly enhances the solubility of TPO, an efficient commercial photoinitiator, thereby eliminating the need for specific organic solvents , but also serves as physical crosslinking points for polymer chains. Moreover, by harnessing the abundant hydrogen bonding present in glycerol and plant cellulose, the precursor hydrogel exhibits a rapid layer-by-layer printing capability of 6 s per layer, accompanied by an enhanced mechanical toughness reaching 4.55 MJ/m³. The hydrogel-based resistance sensor demonstrates wide-ranging detection capabilities and high sensitivity. It has the gauge factor (GF) of 2.28 within low strains (<100 %) and can maintain a high linear GF of 5.84 even under large strains (200–500 %). This allows the hydrogel-based sensor to have a significant change in relative resistance when detecting human limb movements. The lattice structure design imparts a notable pressure sensitivity of 1.13 KPa −1 . Additionally, the utilization of a glycerol/water binary solvent ensures excellent water retention properties. Furthermore, the hydrogel exhibits significant advantages in capacitive sensors owing to its printed surface gradient bulge structure. Consequently, the hydrogel developed in this study possesses exceptional printing abilities, high strength, and impressive toughness, making it a valuable option for the design and fabrication of flexible electronic devices.
研究领域:
材料科学
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3D打印
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传感器
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机械工程
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高分子科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Saudi Chemical Society
·
2021
·
IF 3.932
Yujie Hua,Xican Li,Wenhui Zhang,Ban Chen,Yamei Liu,Xiaojun Zhao,Hong Xie,Dongfeng Chen
Folium Hibisci Mutabilis, a new member of Chinese Pharmacopoeia, can treat some diseases induced by reactive oxygen species. The study prepared a lyophilized aqueous extract of Folium Hibisci Mutabilis (LAFHM). LAFHM was found to enrich eight flavonoids (i.e., quercetin, luteolin, hyperoside, isoquercitrin, rutin, kaempferol, tiliroside, and vitexin) by HPLC analysis. These flavonoids were further compared using antioxidant assays, where triliroside and vitexin always exhibited higher IC 50 values than the others. In ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry analysis, these flavonoids could basically give two characteristic m / z values (226 and 196) and their corresponding double m / z values (i.e., 602, 570, 926, 926, 570, 1186, and 862), when treated by 1,1-diphenyl-2-picryl-hydrazl radical (DPPH • ). Finally, the coupling products of DPPH • -treated triliroside were investigated using computational chemistry. It was found that the –OH in para- coumaroyl moiety to have the lowest bond disassociation energy among all phenolic -OHs in the triliroside. In conclusion, Folium Hibisci Mutabilis contains the above eight antioxidant flavonoids. Despite of the different antioxidant levels, they can generally produce flavonoid-radical coupling product and flavonoid-flavonoid homodimer during antioxidant process. Especially, tiliroside uses para -coumaroyl as linker to construct a tiliroside-radical coupling product at the meta -carbon atom.
研究领域:
药理学
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分析化学
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计算化学
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植物科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）