scholarly journals Elucidating the Quenching Mechanism in Carbon Dot-Metal Interactions–Designing Sensitive and Selective Optical Probes

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1391
Author(s):  
Farah Noun ◽  
Evelyne Anastasia Jury ◽  
Rafik Naccache
Keyword(s):  
Animal Health ◽  
Chemical Properties ◽  
High Sensitivity ◽  
Global Scale ◽  
Detection Sensitivity ◽  
Optical Probes ◽  
One Pot ◽  
Carbon Dot ◽  
Metal Interactions ◽  
Metal Sensors

Overexposure to metals has significant adverse effects on human and animal health coupled with nefarious consequences to the environment. Sensitive tools to measure low contaminant levels exist, but often come at a high cost and require tedious procedures. Thus, there exists a need for the development of affordable metal sensors that can offer high sensitivity and selectivity while being accessible on a global scale. Here, carbon dots, prepared in a one-pot synthesis using glutathione and formamide, have been developed as dual fluorescent metal sensing probes. Following extensive characterization of their physico-chemical properties, it is demonstrated that dual fluorescence can be exploited to build a robust ratiometric sensor with low-ppb detection sensitivity in water. This investigation shows that these optical probes are selective for Pb2+ and Hg2+ ions. Using steady-state and dynamic optical characterization techniques, coupled with hard and soft acid-base theory, the underlying reason for this selective behavior was identified. These findings shed light on the nature of metal-carbon dot interactions, which can be used to tailor their properties to target specific metal ions. Finally, these findings can be applicable to other fluorescent nanoparticle systems that are targeted for development as metal sensors.

scholarly journals Highly Sensitive Fluorescent Detection of Acetylcholine Based on the Enhanced Peroxidase-Like Activity of Histidine Coated Magnetic Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1207
Author(s):  
Hong Jae Cheon ◽  
Quynh Huong Nguyen ◽  
Moon Il Kim
Keyword(s):  
Magnetic Nanoparticles ◽  
High Sensitivity ◽  
High Specificity ◽  
Choline Oxidase ◽  
Fluorescent Detection ◽  
One Pot ◽  
Site Structure ◽  
Specificity And Sensitivity ◽  
Highly Sensitive ◽  
Peroxidase Mimics

Inspired by the active site structure of natural horseradish peroxidase having iron as a pivotal element with coordinated histidine residues, we have developed histidine coated magnetic nanoparticles (His@MNPs) with relatively uniform and small sizes (less than 10 nm) through one-pot heat treatment. In comparison to pristine MNPs and other amino acid coated MNPs, His@MNPs exhibited a considerably enhanced peroxidase-imitating activity, approaching 10-fold higher in catalytic reactions. With the high activity, His@MNPs then were exploited to detect the important neurotransmitter acetylcholine. By coupling choline oxidase and acetylcholine esterase with His@MNPs as peroxidase mimics, target choline and acetylcholine were successfully detected via fluorescent mode with high specificity and sensitivity with the limits of detection down to 200 and 100 nM, respectively. The diagnostic capability of the method is demonstrated by analyzing acetylcholine in human blood serum. This study thus demonstrates the potential of utilizing His@MNPs as peroxidase-mimicking nanozymes for detecting important biological and clinical targets with high sensitivity and reliability.

scholarly journals High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

2021 ◽  
Vol 11 (15) ◽  
pp. 6992
Author(s):  
Tie Zhang ◽  
Yuxin Xing ◽  
Gaoxuan Wang ◽  
Sailing He
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Continuous Monitoring ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Infrared Range ◽  
Wavelength Modulation ◽  
Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

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.

scholarly journals Mini-FLOTAC and McMaster egg counting method for detection of gastrointestinal parasites in small ruminants: a comparison study

2021 ◽  
Vol 15 (2) ◽  
pp. 119-124
Author(s):  
Osires Lustosa Vieira ◽  
Lucia Oliveira Macedo ◽  
Marcos Antônio Bezerra-Santos ◽  
Lucas Azevedo dos Santos ◽  
Carla Lopes de Mendonça ◽  
...  
Keyword(s):  
Animal Health ◽  
Small Ruminants ◽  
High Sensitivity ◽  
Gastrointestinal Parasites ◽  
Comparison Study ◽  
Helminth Eggs ◽  
Nematode Eggs ◽  
Proper Diagnosis ◽  
Flotac Technique ◽  
Sensitivity Specificity

The proper diagnosis of gastrointestinal parasites of small ruminants requires the development of multivalent techniques characterized by high sensitivity, specificity, precision, reproducibility, and the ability to quickly detect and monitor infections that pose risks to animal health. The aim of this study was to evaluate the performance of Mini-FLOTAC technique and McMaster egg counting (gold standard) in the detection of gastrointestinal parasites of goats and sheep. A total of 789 fecal samples were analyzed (401 of sheep and 388 of goats). From those, nematode eggs were detected in 80.86% (638/789), being 72.57% (291/401) from sheep and 89.43% (347/388) from goats. The Mini-FLOTAC technique presented a better performance to detect helminth eggs in both goats (88.40%; 343/388) and sheep (71.57%; 287/401) (?2 = 10.358; p < 0.0001). Kappa analysis revealed a weak concordance between techniques for goats (k = 0.342; p < 0.001) and sheep (k = 0.281; p < 0.001). Data herein reported suggests that the Mini-FLOTAC is a technique more sensitive than the McMaster egg counting, therefore its use might be adopted for the diagnosis of gastrointestinal infection in small ruminants.

scholarly journals Modeling the marine chromium cycle: new constraints on global-scale processes

2021 ◽  
Vol 18 (19) ◽  
pp. 5447-5463
Author(s):  
Frerk Pöppelmeier ◽  
David J. Janssen ◽  
Samuel L. Jaccard ◽  
Thomas F. Stocker
Keyword(s):  
Biological Activity ◽  
Chemical Properties ◽  
Global Scale ◽  
Oxidation States ◽  
The Arctic ◽  
Great Promise ◽  
Concentration Gradients ◽  
Oxygen Minimum Zones ◽  
Cr Concentration ◽  
Critical Regions

Abstract. Chromium (Cr) and its isotopes hold great promise as a tracer of past oxygenation and marine biological activity due to the contrasted chemical properties of its two main oxidation states, Cr(III) and Cr(VI), and the associated isotope fractionation during redox transformations. However, to date the marine Cr cycle remains poorly constrained due to insufficient knowledge about sources and sinks and the influence of biological activity on redox reactions. We therefore implemented the two oxidation states of Cr in the Bern3D Earth system model of intermediate complexity in order to gain an improved understanding on the mechanisms that modulate the spatial distribution of Cr in the ocean. Due to the computational efficiency of the Bern3D model we are able to explore and constrain the range of a wide array of parameters. Our model simulates vertical, meridional, and inter-basin Cr concentration gradients in good agreement with observations. We find a mean ocean residence time of Cr between 5 and 8 kyr and a benthic flux, emanating from sediment surfaces, of 0.1–0.2 nmol cm−2 yr−1, both in the range of previous estimates. We further explore the origin of regional model–data mismatches through a number of sensitivity experiments. These indicate that the benthic Cr flux may be substantially lower in the Arctic than elsewhere. In addition, we find that a refined representation of oxygen minimum zones and their potential to reduce Cr yield Cr(III) concentrations and Cr removal rates in these regions in much improved agreement with observational data. Yet, further research is required to better understand the processes that govern these critical regions for Cr cycling.

scholarly journals DESIGN AND SYNTHESIS OF MOLECULAR TWEEZER BASED ON 3-HYDROXYFLAVONE FOR THE DETECTION OF ATP

2017 ◽  
pp. 67-70
Author(s):  
O. Bugera ◽  
A. Netrebchuk ◽  
V. Pivovarenko
Keyword(s):  
Amino Acid ◽  
Hydrogen Bonds ◽  
Atmospheric Oxygen ◽  
High Sensitivity ◽  
Fluorescence Probes ◽  
Amino Acid Derivative ◽  
One Pot ◽  
Design And Synthesis ◽  
Sensitivity And Selectivity ◽  
Molecular Tweezer

Adenosine 5'-triphosphate (ATP) is known as a universal energy source and signaling mediator in numerous biological processes. Among the methods for its determination, molecular fluorescence probes occupy leading positions due to high sensitivity and selectivity. Recently we have shown that 31 of 33 tested flavones and quinolones of various structures give fluorescence response and can be effectively applied as the probes in aqueous solutions for detection of ATP in 1–50,000 μM range of its concentrations. To increase response parameters of a probe in respect to ATP we have synthesized N,N'-(butane-1,4-diyl)bis(2-((2-(4-(dimethylamino)phenyl)-3-hydroxy-4-oxo-4H-chromene-6-yl)oxy)acetamide, the molecular tweezer composed of two flavonol units connected by active linker. On our idea, being equipped by two planar platforms, the tweezershould demonstrate increased affinity and selectivity to ATP in a result of increased number of hydrogen bonds and increased stacking interactions. Having two NH-amide groups the amino acid linker will form hydrogen bonds with the phosphates of ATP, increasing the portion of probe-ATP complex population in the reporting conformation.In the four-step synthesis of this molecular device, starting from methyl 2-(3-acetyl-4-hydroxyphenoxy)acetate and N,N-dimethylaminobenzaldehyde, the conditions for the reaction of one-pot chalcone formation and its oxidative heterocyclization in the presence of an organic base were found, which resulted in the isolation of a target flavonol-amino acid derivative with high yields. We suggest that atmospheric oxygen was an oxidizer in this process. The obtained derivative was converted intotarget compound by dual condensation with 1,4-butane diamine.

scholarly journals Non-Enzymatic Glucose Sensing Based on Incorporation of Carbon Nanotube into Zn-Co-S Ball-in-Ball Hollow Sphere

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4340
Author(s):  
Han-Wei Chang ◽  
Chia-Wei Su ◽  
Jia-Hao Tian ◽  
Yu-Chen Tsai
Keyword(s):  
Electron Microscopy ◽  
Hollow Sphere ◽  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
High Sensitivity ◽  
Glucose Sensing ◽  
Ionic Exchange ◽  
X Ray ◽  
Transmission Electron ◽  
Electro Oxidation

Zn-Co-S ball-in-ball hollow sphere (BHS) was successfully prepared by solvothermal sulfurization method. An efficient strategy to synthesize Zn-Co-S BHS consisted of multilevel structures by controlling the ionic exchange reaction was applied to obtain great performance electrode material. Carbon nanotubes (CNTs) as a conductive agent were uniformly introduced with Zn-Co-S BHS to form Zn-Co-S BHS/CNTs and expedited the considerable electrocatalytic behavior toward glucose electro-oxidation in alkaline medium. In this study, characterization with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) was used for investigating the morphological and physical/chemical properties and further evaluating the feasibility of Zn-Co-S BHS/CNTs in non-enzymatic glucose sensing. Electrochemical methods (cyclic voltammetry (CV) and chronoamperometry (CA)) were performed to investigate the glucose sensing performance of Zn-Co-S BHS/CNTs. The synergistic effect of Faradaic redox couple species of Zn-Co-S BHS and unique conductive network of CNTs exhibited excellent electrochemical catalytic ability towards the glucose electro-oxidation, which revealed linear range from 5 to 100 μM with high sensitivity of 2734.4 μA mM−1 cm−2, excellent detection limit of 2.98 μM, and great selectivity in the presence of dopamine, uric acid, ascorbic acid, and fructose. Thus, Zn-Co-S BHS/CNTs would be expected to be a promising material for non-enzymatic glucose sensing.

One-pot synthesis of (anatase/bronze-type)-TiO2/carbon dot polymorphic structures and their photocatalytic activity for H2 generation

2020 ◽  
Vol 526 ◽  
pp. 146650 ◽  
Author(s):  
Sovann Khan ◽  
Yuta Kubota ◽  
Wenwei Lei ◽  
Norihiro Suzuki ◽  
Kazuya Nakata ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
One Pot ◽  
Carbon Dot ◽  
H2 Generation ◽  
One Pot Synthesis

A protein triggering exponential amplification reaction enables label- and wash-free one-pot protein assay with high sensitivity

Talanta ◽  
2021 ◽  
Vol 225 ◽  
pp. 121980
Author(s):  
Jun Chen ◽  
Yanfei Zhang ◽  
Bao-Ping Xie ◽  
Bin Sun ◽  
Wen-Jun Duan ◽  
...  
Keyword(s):  
High Sensitivity ◽  
One Pot ◽  
Protein Assay ◽  
Amplification Reaction

scholarly journals One-Pot Synthesis of Photoluminescent Self-Assembled Carbon Dot Monolayer Films

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Hongchong Guo ◽  
Wei Li ◽  
Gang Sun ◽  
Bo You
Keyword(s):  
Copper Acetate ◽  
Coating Films ◽  
Self Assembled Monolayer ◽  
Monolayer Films ◽  
One Pot ◽  
Carbon Dot ◽  
Phase Medium ◽  
Oil Water ◽  
Self Assembled ◽  
Oxidation System

We propose a facile and simple synthesis of photoluminescent (PL) carbon dot self-assembled monolayer films (CD-SAMFs) at oil-water interfaces. By using styrene both as the carbon source and the oil phase medium, we got our amazing CD-SAMFs under the copper acetate and hydrogen peroxide (Cu(Ac)2-H2O2) catalytic-oxidation system. Without any surface modification, the spontaneously formed CD-SAMFs exhibit ultrathin thickness (<10 nm), bright luminescence, high transparency, and hydrophobicity, which have the potential as a new alternative to be used on multifunctional coating films, anticounterfeiting, displays, sensors, and optical devices.

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