EXPRESS: A Lanthanide Complex Fluorescent Probe for the Detection of Melamine

2021 ◽  
pp. 000370282110223
Author(s):  
Xiaolin Li ◽  
Chaoqun Ma ◽  
Lei Li ◽  
Hui Gao ◽  
Jiao Gu ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Chemical Properties ◽  
Lanthanide Complex ◽  
High Sensitivity ◽  
Radiative Energy ◽  
Radiative Energy Loss ◽  
Time Resolved ◽  
Small Molecule Compound ◽  
The Rich

Melamine is a kind of small molecule compound, which has been illegally adulterated in dairy food because of the rich nitrogen content and stable chemical properties. Therefore, the detection of melamine is of great significance to food safety and human's health protection. Melamine can emit weak fluorescence, making it difficult to detect melamine directly. However melamine can significantly enhance the emission of the tetracycline-europium (EuTC) complex at a wavelength of 616 nm, hence this work uses EuTC complex as a fluorescent probe to detect melamine. According to the characterizations of absorption spectra, molecular electrostatic potential distribution and the time-resolved spectra, we speculated that tetracycline and melamine may form a complex through hydrogen bonding interaction, causing the melamine closer approach to Eu3+ and reducing the non-radiative energy loss of water molecules to EuTC complex, which significantly enhanced the fluorescence intensity of EuTC. The fluorescence intensity with melamine concentration in the range of 0.5~40 μM shows a good linear relationship, and the correlation coefficient is 0.9951 with the detection limit of 0.0785 μM, which shows a high sensitivity in detection of melamine. As far as we know, EuTC complex is the first time that has been used as a fluorescent probe to detect melamine, which provides a supplement and extension for the detection of melamine in fluorescence spectroscopy.

scholarly journals 2-aminopurine as a fluorescent probe of DNA conformation and the DNA–enzyme interface

2015 ◽  
Vol 48 (2) ◽  
pp. 244-279 ◽  
Author(s):  
Anita C. Jones ◽  
Robert K. Neely
Keyword(s):  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Photophysical Properties ◽  
Fluorescence Decay ◽  
Structural Isomer ◽  
Time Resolved ◽  
Use Of Time ◽  
Fluorescence Measurements ◽  
Natural Base ◽  
Decay Parameters

AbstractNearly 50 years since its potential as a fluorescent base analogue was first recognized, 2-aminopurine (2AP) continues to be the most widely used fluorescent probe of DNA structure and the perturbation of that structure by interaction with enzymes and other molecules. In this review, we begin by considering the origin of the dramatic and intriguing difference in photophysical properties between 2AP and its structural isomer, adenine; although 2AP differs from the natural base only in the position of the exocyclic amine group, its fluorescence intensity is one thousand times greater. We then discuss the mechanism of interbase quenching of 2AP fluorescence in DNA, which is the basis of its use as a conformational probe but remains imperfectly understood. There are hundreds of examples in the literature of the use of changes in the fluorescence intensity of 2AP as the basis of assays of conformational change; however, in this review we will consider in detail only a few intensity-based studies. Our primary aim is to highlight the use of time-resolved fluorescence measurements, and the interpretation of fluorescence decay parameters, to explore the structure and dynamics of DNA. We discuss the salient features of the fluorescence decay of 2AP when incorporated in DNA and review the use of decay measurements in studying duplexes, single strands and other structures. We survey the use of 2AP as a probe of DNA-enzyme interaction and enzyme-induced distortion, focusing particularly on its use to study base flipping and the enhanced mechanistic insights that can be gained by a detailed analysis of the decay parameters, rather than merely monitoring changes in fluorescence intensity. Finally we reflect on the merits and shortcomings of 2AP and the prospects for its wider adoption as a fluorescence-decay-based probe.

Nitrogen and Sulfur Co-doped Fluorescent Carbon Dots for the Detection of Morin and Cell Imaging

2018 ◽  
Vol 15 (1) ◽  
pp. 47-55
Author(s):  
Xuebing Li ◽  
Haifen Yang ◽  
Ning Wang ◽  
Tijian Sun ◽  
Wei Bian ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Carbon Dots ◽  
Cell Imaging ◽  
Water Soluble ◽  
Heating Process ◽  
X Ray ◽  
Doped Carbon Dots ◽  
Co Doped

Background: Morin has many pharmacological functions including antioxidant, anticancer, anti-inflammatory, and antibacterial effects. It is commonly used in the treatment of antiviral infection, gastropathy, coronary heart disease and hepatitis B in clinic. However, researches have shown that morin is likely to show prooxidative effects on the cells when the amount of treatment is at high dose, leading to the decrease of intracellular ATP levels and the increase of necrosis process. Therefore, it is necessary to determine the concentration of morin in biologic samples. Method: Novel water-soluble and green nitrogen and sulfur co-doped carbon dots (NSCDs) were prepared by a microwave heating process with citric acid and L-cysteine. The fluorescence spectra were collected at an excitation wavelength of 350 nm when solutions of NSCDs were mixed with various concentrations of morin. Results: The as-prepared NSCDs were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The fluorescence intensity of NSCDs decreased significantly with the increase of morin concentration. The fluorescence intensity of NSCDs displayed a linear response to morin in the concentration 0.10-30 μM with a low detection limit of 56 nM. The proposed fluorescent probe was applied to analysis of morin in human body fluids with recoveries of 98.0-102%. Conclusion: NSCDs were prepared by a microwave heating process. The present analytical method is sensitive to morin. The quenching process between NSCDs and morin is attributed to the static quenching. In addition, the cellular toxicity on HeLa cells indicated that the as-prepared NSCDs fluorescent probe does not show obvious cytotoxicity in cell imaging. Our proposed method possibly opens up a rapid and nontoxic way for preparing heteroatom doped carbon dots with a broad application prospect.

scholarly journals Effects of Crystal Morphology on the Hot-Carrier Dynamics in Mixed-Cation Hybrid Lead Halide Perovskites

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 708
Author(s):  
Daniele Catone ◽  
Giuseppe Ammirati ◽  
Patrick O’Keeffe ◽  
Faustino Martelli ◽  
Lorenzo Di Mario ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Carrier Dynamics ◽  
Large Area ◽  
Photovoltaic Properties ◽  
Time Resolved ◽  
Hot Carrier ◽  
Mixed Cation ◽  
Small Crystals ◽  
Characterization Of Materials ◽  
Lead Halide

Ultrafast pump-probe spectroscopies have proved to be an important tool for the investigation of charge carriers dynamics in perovskite materials providing crucial information on the dynamics of the excited carriers, and fundamental in the development of new devices with tailored photovoltaic properties. Fast transient absorbance spectroscopy on mixed-cation hybrid lead halide perovskite samples was used to investigate how the dimensions and the morphology of the perovskite crystals embedded in the capping (large crystals) and mesoporous (small crystals) layers affect the hot-carrier dynamics in the first hundreds of femtoseconds as a function of the excitation energy. The comparative study between samples with perovskite deposited on substrates with and without the mesoporous layer has shown how the small crystals preserve the temperature of the carriers for a longer period after the excitation than the large crystals. This study showed how the high sensitivity of the time-resolved spectroscopies in discriminating the transient response due to the different morphology of the crystals embedded in the layers of the same sample can be applied in the general characterization of materials to be used in solar cell devices and large area modules, providing further and valuable information for the optimization and enhancement of stability and efficiency in the power conversion of new perovskite-based devices.

Urinary gonadotropin measurements by enhanced luminometric assays (LIA) for the evaluation of pubertal development

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
And Demir ◽  
Adem Aydın ◽  
Atilla Büyükgebiz ◽  
Ulf-Håkan Stenman ◽  
Matti Hero
Keyword(s):  
Healthy Subjects ◽  
Reliable Method ◽  
Pubertal Development ◽  
High Sensitivity ◽  
Tanner Stage ◽  
Time Resolved ◽  
Stage 1 ◽  
Sensitive Detection Technique ◽  
Serum And Urine

Abstract Objectives Determination of LH in urine has proved to be a reliable method for evaluation of pubertal development. The human LH assay based on time-resolved immunofluorometric (IFMA) technology (AutoDELFIA, PerkinElmer, Wallac) has been found to be suitable for this purpose thanks to its high sensitivity but other assays have not been evaluated. We have analyzed our data obtained by another potentially sensitive detection technique, enhanced luminometric assay (LIA) with the objective of finding a viable alternative to IFMA since these may not be available in the future. Methods LIA was used to measure LH and FSH in serum and urine samples from 100 healthy subjects of each Tanner stage and both genders, whose pubertal development has been determined. Results Urinary gonodotropin concentrations measured by LIA correlated well with Tanner stage [(r=0.93 for girls, r=0.81 for boys; p<0.01 for LH) and (r=0.81 for girls, r=0.73 for boys; p<0.01 for FSH)]. LIA determinations revealed the increase in U-LH concentrations during the transition from Tanner stage 1–2 in both girls and boys (p<0.001), whereas U-FSH and S-LH were able to detect the increase from Tanner stage 1–2 only in boys or girls, respectively (both p<0.001). Conclusions Measurement of urinary gonadotropin concentrations by LIA may be useful for the evaluation of overall pubertal development and also in the detection of transition from prepuberty to puberty.

Highly sensitive, stable, and precise detection of dopamine with carbon dots/tyrosinase hybrid as fluorescent probe

RSC Advances ◽  
2014 ◽  
Vol 4 (87) ◽  
pp. 46437-46443 ◽  
Author(s):  
Hao Li ◽  
Juan Liu ◽  
Manman Yang ◽  
Weiqian Kong ◽  
Hui Huang ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Carbon Dots ◽  
Low Cost ◽  
High Sensitivity ◽  
Highly Sensitive

The carbon dots/tyrosinase hybrid as a low-cost fluorescent probe for the detection of dopamine exhibits high sensitivity, stability, and precision.

scholarly journals The Radiative Energy Loss from the Shock Front

1973 ◽  
Vol 49 (6) ◽  
pp. 1911-1931 ◽  
Author(s):  
Shinji Narita
Keyword(s):  
Energy Loss ◽  
Shock Front ◽  
Radiative Energy ◽  
Radiative Energy Loss

Synthesis of Cu2O and ZnO Nanowires and their Heterojunction Nanowires by Thermal Evaporation: A Short Review

2014 ◽  
Vol 71 (5) ◽  
Author(s):  
Muhammad Arif Khan ◽  
Samsudi Sakrani ◽  
Syahida Suhaima ◽  
Yussof Wahab ◽  
Rosnita Muhammad
Keyword(s):  
Physical Vapor Deposition ◽  
Thermal Evaporation ◽  
Chemical Properties ◽  
High Sensitivity ◽  
Short Review ◽  
Zno Nanowires ◽  
Oxide Semiconductor ◽  
The Individual ◽  
Photovoltaic Solar Cells ◽  
Physical And Chemical

One dimensional metal oxide semiconductor nanowires of copper (I) oxide (Cu2O), zinc oxide (ZnO), and their heterojunction nanowires possess remarkable physical and chemical properties. ZnO and Cu2O areattractive because the metals are abundant on earth, inexpensive, nontoxic.Moreover, these oxides have useful optical and electrical properties suitable for a wide variety of electrical devices, because their electrical conduction can be predictably controlled by doping. We here restrict the disscussion using a Hot Tube Vacuum Thermal Evaporation. The NWs in these devices will be studied by physical vapor deposition known as vapor-liquid-solid (VLS). Therefore, we explore conventional methods, particularly the VLS of growing ZnO and Cu2O nanowires which are assisted by the catalyst.  In this short review, we report the individual and combined (Cu2O/ZnO) junction nanowires by PVD method.  The main advantages of these composite nanowires are the natural p-n characteristics, the broad light absorption, the high sensitivity to humidity changes, and the fast dynamic response. The combination of all characteristics offered by Cu2O/ZnO nanowires can enable the fabrication of diverse sensing devices, and photovoltaic solar cells.

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