Acquisition of Optimum Co-sources of Sulfur MAA Capped-ZnS Quantum Dots Conditions for Photoluminescence Chlorine Sensor

2021 ◽  
Author(s):  
Jehan Elnady ◽  
Tosson Shaala ◽  
Moataz Soliman ◽  
Shaker Ebrahim ◽  
ahmed elshaer
Keyword(s):  
Quantum Dots ◽  
Hydrothermal Method ◽  
Limit Of Detection ◽  
Average Diameter ◽  
Peak Shift ◽  
Morphological Properties ◽  
Mercaptoacetic Acid ◽  
Zinc Vacancy ◽  
Cubic Structure ◽  
Pl Intensity

Abstract ZnS quantum dots (QDs) has received a great attention due to its unique properties and wide applications. The objective of this work is to synthesize ZnS QDs by hydrothermal method and capped with mercaptoacetic acid (MAA) to be used as a chlorine sensor in the range from 1 to 35 mg/L. Optical, structural and morphological properties of MAA capped-ZnS QDs were investigated. MAA capped-ZnS QDs exhibited a cubic structure with an average diameter size of 8.8 nm. Photoluminescence (PL) spectra of the fabricated MAA capped-ZnS QDs revealed three basic emission peaks at 371, 423 and 486 nm due to level transitions involving of zinc vacancy, interstitial sulfur and zinc, respectively. The photostability of the MAA capped-ZnS QDs was examined after 14 months which retains 12% of the original PL intensity without any peak shift. The MAA capped-ZnS QDs PL intensity was changed linearly with the chlorine concentration in the range from 1 to 35 mg/L with correlation coefficient, sensitivity and limit of detection of 0.9782, 6.96×10-2 ppm-1 and 3.6 mg/L, respectively.

Hydrothermal Synthesis of Polyethyleneimine Modified Carbon Quantum Dots for Sensitively Detection of Cobalt Ions

2021 ◽  
Vol 21 (4) ◽  
pp. 2099-2108
Author(s):  
Yong Zhang ◽  
Changjian Zhu ◽  
Yaqing Zhang ◽  
Na Jing ◽  
Yingte Wang
Keyword(s):  
Quantum Dots ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
Tap Water ◽  
Average Diameter ◽  
Carbon Quantum Dots ◽  
Fluorescence Excitation ◽  
Cobalt Ions ◽  
Transmission Electron ◽  
Morphology Characteristics

In this work, fluorescent carbon quantum dots (CQDs) was prepared using natural on ions as carbon source with hydrothermal method and it was modified with polyethyleneimine (PEI). The properties of PEI modified CQDs (PEI-CQDs) were characterized by fluorescence, infrared spectroscopy and ultraviolet method, the morphology characteristics of PEI-CQDs was observed by transmission electron microscope. The results shown that the fluorescence excitation and emission wavelength were at 340 nm/462 nm, respectively. The fluorescence quantum yield was 8.68%, the average diameter of the PEI-CQDs was 2.82 nm. The infrared showed that the PEI-CQDs contained hydroxyl and amino groups on its surface. The Co2+ has selective quenching effects on fluorescence of PEICQDs, PEI-CQDs can be used for detection and analysis of Co2+ in samples. The limit of detection and linear range of Co2+ using the PEI-CQDs as fluorescence probe are 0.048 μM and 0.05–11 μM, respectively. The recovery was in the range of 97.00–100.64%. Moreover, the PEI-CQDs are also successfully utilized for monitoring the Co2+ content of tap water.

Detection of Glucose in Human Serum Based on Silicon Dot Probe

2020 ◽  
Vol 16 (6) ◽  
pp. 744-752
Author(s):  
Kuan Luo ◽  
Xinyu Jiang
Keyword(s):  
Quantum Dots ◽  
Blood Glucose ◽  
Human Serum ◽  
Organic Dyes ◽  
Limit Of Detection ◽  
Fasting Blood Glucose ◽  
Glucose Biosensor ◽  
Metal Nanoclusters ◽  
Glucose Levels ◽  
Highly Sensitive

Background: Diabetes Mellitus (DM) is a major public metabolic disease that influences 366 million people in the world in 2011, and this number is predicted to rise to 552 million in 2030. DM is clinically diagnosed by a fasting blood glucose that is equal or greater than 7 mM. Therefore, the development of effective glucose biosensor has attracted extensive attention worldwide. Fluorescence- based strategies have sparked tremendous interest due to their rapid response, facile operation, and excellent sensitivity. Many fluorescent compounds have been employed for precise analysis of glucose, including quantum dots, noble metal nanoclusters, up-converting nanoparticles, organic dyes, and composite fluorescent microspheres. Silicon dot as promising quantum dots materials have received extensive attention, owing to their distinct advantages such as biocompatibility, low toxicity and high photostability. Methods: MnO2 nanosheets on the Si nanoparticles (NPs) surface serve as a quencher. Si NPs fluorescence can make a recovery by the addition of H2O2, which can reduce MnO2 to Mn2+, and the glucose can thus be monitored based on the enzymatic conversion of glucose by glucose oxidase to generate H2O2. Therefore, the glucose concentration can be derived by recording the fluorescence recovery spectra of the Si NPs. Results: This probe enabled selective detection of glucose with a linear range of 1-100 μg/mL and a limit of detection of 0.98 μg/mL. Compared with the commercial glucometer, this method showed favorable results and convincing reliability. Conclusion: We have developed a novel method based on MnO2 -nanosheet-modified Si NPs for rapid monitoring of blood glucose levels. By combining the highly sensitive H2O2/MnO2 reaction with the excellent photostability of Si NPs, a highly sensitive, selective, and cost-efficient sensing approach for glucose detection has been designed and applied to monitor glucose levels in human serum with satisfactory results.

scholarly journals Scalable Production of Boron Quantum Dots for Broadband Ultrafast Nonlinear Optical Performance

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 687
Author(s):  
Shuolei Meng ◽  
Qianyuan Chen ◽  
Hongjian Lin ◽  
Feng Zhou ◽  
Youning Gong ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Relaxation Time ◽  
Nonlinear Optical ◽  
Average Diameter ◽  
Optical Devices ◽  
Nonlinear Optical Properties ◽  
Saturable Absorption ◽  
Nonlinear Optical Susceptibility ◽  
Tandem Structure

A simple and effective approach based on the liquid phase exfoliation (LPE) method has been put forward for synthesizing boron quantum dots (BQDs). By adjusting the interactions between bulk boron and various solvents, the average diameter of produced BQDs is about 7 nm. The nonlinear absorption (NLA) responses of as-prepared BQDs have been systematically studied at 515 nm and 1030 nm. Experimental results prove that BQDs possess broadband saturable absorption (SA) and good third-order nonlinear optical susceptibility, which are comparable to graphene. The fast relaxation time and slow relaxation time of BQDs at 515 nm and 1030 nm are about 0.394–5.34 ps and 4.45–115 ps, respectively. The significant ultrafast nonlinear optical properties can be used in optical devices. Here, we successfully demonstrate all-optical diode application based on BQDs/ReS2 tandem structure. The findings are essential for understanding the nonlinear optical properties in BQDs and open a new pathway for their applications in optical devices.

scholarly journals Facile Synthesis of L-Cysteine Functionalized Graphene Quantum Dots as a Bioimaging and Photosensitive Agent

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1879
Author(s):  
Mila Milenković ◽  
Aleksandra Mišović ◽  
Dragana Jovanović ◽  
Ana Popović Bijelić ◽  
Gabriele Ciasca ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Gamma Irradiation ◽  
Hela Cells ◽  
Graphene Quantum Dots ◽  
Morphological Properties ◽  
Paramagnetic Resonance ◽  
Chemical Reagents ◽  
Amino Amide ◽  
Gamma Irradiated ◽  
Electron Paramagnetic

Nowadays, a larger number of aggressive and corrosive chemical reagents as well as toxic solvents are used to achieve structural modification and cleaning of the final products. These lead to the production of residual, waste chemicals, which are often reactive, cancerogenic, and toxic to the environment. This study shows a new approach to the modification of graphene quantum dots (GQDs) using gamma irradiation where the usage of reagents was avoided. We achieved the incorporation of S and N atoms in the GQD structure by selecting an aqueous solution of L-cysteine as an irradiation medium. GQDs were exposed to gamma-irradiation at doses of 25, 50 and 200 kGy. After irradiation, the optical, structural, and morphological properties, as well as the possibility of their use as an agent in bioimaging and photodynamic therapy, were studied. We measured an enhanced quantum yield of photoluminescence with the highest dose of 25 kGy (21.60%). Both S- and N-functional groups were detected in all gamma-irradiated GQDs: amino, amide, thiol, and thione. Spin trap electron paramagnetic resonance showed that GQDs irradiated with 25 kGy can generate singlet oxygen upon illumination. Bioimaging on HeLa cells showed the best visibility for cells treated with GQDs irradiated with 25 kGy, while cytotoxicity was not detected after treatment of HeLa cells with gamma-irradiated GQDs.

Electrostatic repulsion strategy for highly selective and sensitive “switch–on” fluorescence sensor of ascorbic acid based on the cysteamine-coated CdTe quantum dots and cerium (IV)

2021 ◽  
Author(s):  
Yifei Guo ◽  
Jingjing Du ◽  
Jianjun Li ◽  
Ran Yang ◽  
Peter B. de Harrington ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ascorbic Acid ◽  
Hydrothermal Method ◽  
Cadmium Chloride ◽  
Fluorescence Sensor ◽  
Cdte Quantum Dots ◽  
Electrostatic Repulsion ◽  
Functional Monomer ◽  
Simple Hydrothermal Method ◽  
Cdte Qds

In this work, cysteamine-coated CdTe quantum dots (CA-CdTe QDs) were synthesized by a simple hydrothermal method employing cadmium chloride as the cadmium source and cysteamine hydrochloride as the functional monomer....

Optical and morphological properties of In(Ga)As/GaAs quantum dots grown on novel index surfaces

1999 ◽  
Vol 30 (4-5) ◽  
pp. 419-425 ◽  
Author(s):  
S. Sanguinetti ◽  
A. Miotto ◽  
S. Castiglioni ◽  
E. Grilli ◽  
M. Guzzi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Morphological Properties

Preparation of NiO Microspheres by Hydrothermal Method and its Electrochemical Capacitive Properties

2015 ◽  
Vol 814 ◽  
pp. 81-85 ◽  
Author(s):  
Qian Qian Li ◽  
Run Hua Fan ◽  
Ke Lan Yan ◽  
Kai Sun ◽  
Xu Ai Wang ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Electrochemical Impedance ◽  
Specific Capacity ◽  
Rate Capability ◽  
Average Diameter ◽  
Three Dimensions ◽  
Electrochemical Characteristics ◽  
X Ray Diffraction ◽  
High Specific Capacity ◽  
Capacitive Properties

The precursor Ni (OH)2 was synthesized by a simple hydrothermal method with hexamethylenetetramine ((CH2)6N4) as precipitant and template, and then NiO was gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical capacitive characterization was performed using cyclic voltammetry (CV), chronopotentiometry and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result shows that spherical NiO without impurity was synthesized, the average diameter of the spheres is 5 um and these spheres were constructed by the interactive arrangement of many nanoflakes in three dimensions. This kind of NiO shows the typical electrochemical characteristics of pseudo capacitance with high specific capacity and excellent rate capability. The specific capacity can reach 515F/g at the current density of 1A/g

An optical ratiometric temperature sensor based on dopant-dependent thermal equilibrium in dual-emitting Ag&Mn:ZnInS quantum dots

RSC Advances ◽  
2016 ◽  
Vol 6 (63) ◽  
pp. 58113-58117 ◽  
Author(s):  
Guangguang Huang ◽  
Chunlei Wang ◽  
Xiaojing Xu ◽  
Yiping Cui
Keyword(s):  
Quantum Dots ◽  
Optical Sensor ◽  
Temperature Sensor ◽  
Thermal Equilibrium ◽  
Temperature Detection ◽  
Pl Intensity

A novel optical sensor for ratiometric temperature detection is devised via Ag&Mn:ZnInS quantum dots (QDs). The temperature can be read via the PL ratios of Ag-related and Mn-related PL intensity.

Three-Pulse Photon Echo Peak Shift Measurements of Capped CdSe Quantum Dots

2009 ◽  
Vol 114 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Lachlan J. McKimmie ◽  
Craig N. Lincoln ◽  
Jacek Jasieniak ◽  
Trevor A. Smith
Keyword(s):  
Quantum Dots ◽  
Photon Echo ◽  
Peak Shift ◽  
Cdse Quantum Dots ◽  
Pulse Photon ◽  
Photon Echo Peak Shift
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