quenching effect
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2022 ◽  
Author(s):  
Pingwu Du ◽  
Xinyu Zhang ◽  
Huiqing Liu ◽  
Guilin Zhuang ◽  
Shangfeng Yang

Herein we report a novel chiral bismacrocycle with unexpected dual emission and tunable aggregation-induced emission colors. A facile four-step synthesis strategy is developed to construct this rigid bismacrocycle, (1,4)[8]cycloparaphenylenophane (SCPP[8]), which possesses a 1,2,4,5-tetraphenylbenzene core locked by two intersecting polyphenylene-based macrocycles. The luminescent behavior of SCPP[8] shows the unique characteristics of both aggregation-caused quenching effect and aggrega-tion-induced emission (AIE) effect, inducing remarkable redshift emission including near white-light emission. SCPP[8] is configurationally stable and possesses a novel shape-persistent bismacrocycle scaffold with a high strain energy (up to 127.83 kcal/mol). In addition, SCPP[8] displays enhanced circularly polarized luminescence properties due to AIE effect.


2022 ◽  
Author(s):  
Beibei Feng ◽  
Fei Zhao ◽  
Min Wei ◽  
Yong Liu ◽  
Xinyu Ren ◽  
...  

Abstract On the basis of aptamer (Apt) with hairpin structure and fluorescence resonance energy transfer (FRET), a ratio fluorescent aptamer homogeneous sensor was prepared for the determination of Aflatoxin B1 (AFB1). Initially, the Apt labeled simultaneously with Cy5, BHQ2, and cDNA labeled with Cy3 were formed a double-stranded DNA through complementary base pairing. The fluorescent aptamer sensor demonstrates a weak fluorescence emission of Cy3 and a high fluorescence emission of Cy5 due to the quenching effect of BHQ2. The double-stranded DNA structure will be disintegrated in the presence of AFB1, resulting the removal of Cy3 and the close of Cy5 with BHQ2. The fluorescence signal of Cy3 and Cy5 were restored and quenched respectively. Thus, the ratio change of FCy3 to FCy5 was used to realized the detection of AFB1 with wider detection range and lower limit of detection (LOD). The response of the optimized protocol for AFB1 detection was wider linear range from 0.05 ng/mL to 100 ng/mL and the LOD was 12.6 pg/mL. The sensor designed in this strategy has the advantages of simple preparation and fast signal response. It has been used for the detection of AFB1 in labeled corn and wine, indicating it had good application potential in practical samples.


Author(s):  
Ziyue Xu ◽  
Weipeng Mao ◽  
Zizhen Zhao ◽  
Zekun Wang ◽  
Yue-Yang Liu ◽  
...  

Water-soluble three-dimensional supramolecular-organic frameworks (SOFs) and temoporfin (mTHPC) are discovered to form uniform self-assembly nanoparticles. These nanoparticles demonstrate an improved 1O2 generation efficiency due to a reduced aggregation-caused quenching effect....


2022 ◽  
Vol 130 (3) ◽  
pp. 428
Author(s):  
Н.В. Петроченкова ◽  
Т.Б. Емелина ◽  
А.Г. Мирочник

There were studied the luminescent chemosensory properties of Eu(III) carboxylatodibenzoylmethanates with acetic and acrylic acids while the interaction with ammonia vapors. Quantitative measurements of the optical response showed that with an increase in the analyte concentration in the range of 3-330 ppm, a linear increase in the luminescence intensity of europium(III) is observed. The reversibility of the luminescent response was established, the limit of detection of ammonia was 3 ppm. The mechanism of the optical effect is revealed by the method of quantum chemical modeling: the interaction of ammonia with the sensor leads to the formation of a rigid structural fragment of H2O–NH3, which blocks the quenching effect of high-frequency OH vibrations on luminescence. The studied chemosensors have high sensitivity and selectivity and, thus, can be promising for creating ammonia detection sensors for food safety control and environmental monitoring.


Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 193
Author(s):  
Xinli Wang ◽  
Xiang Lin ◽  
Renfu Li ◽  
Zexin Wang ◽  
Wei Liu ◽  
...  

In this work, we synthesized a pair of positional isomers by attaching a small electron-donating pyrrolidinyl group at ortho- and para-positions of a conjugated core. These isomers exhibited totally different fluorescent properties. PDB2 exhibited obvious aggregation-induced emission properties. In contrast, PDB4 showed the traditional aggregation-caused quenching effect. Their different fluorescent properties were investigated by absorption spectroscopy, fluorescence spectroscopy, density functional theory calculations and single-crystal structural analysis. These results indicated that the substituent position of the pyrrolidinyl groups affects the twisted degree of the isomers, which further induces different molecular packing modes, thus resulting in different fluorescent properties of these two isomers. This molecular design concept provided a new accurate strategy for designing new aggregation-induced emission luminogens.


Marine Drugs ◽  
2021 ◽  
Vol 20 (1) ◽  
pp. 13
Author(s):  
Xiaoshan Long ◽  
Xiao Hu ◽  
Shaobo Zhou ◽  
Huan Xiang ◽  
Shengjun Chen ◽  
...  

Gracilaria lemaneiformis polysaccharide (GLP) exhibits good physiological activities, and it is more beneficial as it is degraded. After its degradation by hydrogen peroxide combined with vitamin C (H2O2-Vc) and optimized by Box–Behnken Design (BBD), a new product of GLP-HV will be generated. While using GLP as control, two products of GLP-H (H2O2-treated) and GLP-V (Vc-treated) were also produced. These products chemical characteristics (total sugar content, molecular weight, monosaccharide composition, UV spectrum, morphological structure, and hypolipidemic activity in vitro) were assessed. The results showed that the optimal conditions for H2O2-Vc degradation were as follows: H2O2-Vc concentration was 18.7 mM, reaction time was 0.5 h, and reaction temperature was 56 °C. The total sugar content of GLP and its degradation products (GLP-HV, GLP-H and GLP-V) were more than 97%, and their monosaccharides are mainly glucose and galactose. The SEM analysis demonstrated that H2O2-Vc made the structure loose and broken. Moreover, GLP, GLP-HV, GLP-H, and GLP-V had significantly inhibition effect on α-glucosidase, and their IC50 value were 3.957, 0.265, 1.651, and 1.923 mg/mL, respectively. GLP-HV had the best inhibition effect on α-glucosidase in a dose-dependent manner, which was the mixed type of competitive and non-competitive. It had a certain quenching effect on fluorescence of α-glucosidase, which may be dynamic quenching.


Author(s):  
Hesham Salem ◽  
Amany Abdelaziz ◽  
Aliaa Gamal ◽  
Ramy El Sabaa

A dependable, sensitive, basic and cheap spectrofluorimetric approach has been created for test of sulfur-containing drug; ixabepilone in bulk powder, vials and human plasma. The approach depends on the quenching effect of ixabepilone on the fluorescence intensity of acetoxymercuric fluorescene (AMF) reagent at λem of 530 nm and λex of 500 nm. Parameters which will control the reaction such as pH, AMF solution concentration, temperature, time and solvents were examined and optimized. According to the optimized conditions, the proposed approach was practiced over the concentration area of 20-100 ng mL-1 with adequate linearity (r = 0.9998). The developed approach was approved confirming to ICH rules in terms of accuracy, precision, linearity, LOD and LOQ. The proposed approach was practiced to analyze ixabepilone in Ixempra® vials with satisfactory recovery % of 99.89 and RSE% of 1.24. The results achieved were compared to those achieved by an already reported HPLC approach.


2021 ◽  
Vol 14 (12) ◽  
pp. 1314
Author(s):  
Hung-Ju Lin ◽  
Chun-Chi Wang ◽  
Hwang-Shang Kou ◽  
Cheng-Wei Cheng ◽  
Shou-Mei Wu

Highly stable and facile one-pot copper nanoclusters (Cu NCs) coated with poly(allylamine hydrochloride) (PAH) have been synthesized for selectively sensing deferasirox (DFX) in β-thalassemia plasma. DFX is an important drug used for treating iron overloading in β-thalassemia, but needs to be monitored due to certain toxicity. In this study, the PAH-Cu NCs showed highly stable fluorescence with emission wavelengths at 450 nm. The DFX specifically interacted with the copper nanocluster to turn off the fluorescence of the PAH-Cu NCs, and could be selectively quantified through the fluorescence quenching effect. The linear range of DFX in plasma analyzed by PAH-Cu NCs was 1.0–100.0 µg/mL (r = 0.985). The relative standard deviation (RSD) and relative error (RE) were lower than 6.51% and 7.57%, respectively, showing excellent reproducibility of PAH-Cu NCs for sensing DFX in plasma. This method was also successfully applied for an analysis of three clinical plasma samples from β-thalassemia patients taking DFX. The data presented high similarity with that obtained through a capillary electrophoresis method. According to the results, the PAH-Cu NCs could be used as a tool for clinically sensing DFX in human plasma for clinical surveys.


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