Cds Quantum Dots
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2021 ◽  
Vol 27 (9) ◽  
Author(s):  
Mahmoud A. S. Sakr ◽  
Sayed A. Abdel Gawad ◽  
Samy A. El-Daly ◽  
Maram T. H. Abou Kana ◽  
El-Zeiny M. Ebeid

AbstractThis manuscript includes some photophysical parameters and some optical properties such as absorption and emission spectra of the (E, E)-2,5-bis (3,4-dimethoxystyryl) pyrazine (BDP) by applying sol–gel and copolymer matrices. The BDP molecular structure is incorporated in sol–gel matrix and copolymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). In case of sol–gel matrix, the BDP molecular structure has higher quantum yield in addition to photostability maxima. The laser behavior of this molecular structure containing sol–gel matrix is good senior compared to copolymer one via using diode laser (450 nm) as pumping laser of power 160 mW. Also, the fluorescence profile of the BDP molecular structure is sensitized via using cadmium sulfide (CdS) quantum dots (QDs) by applying sol–gel host. The optimized structure of the BDP molecule is obtained via applying B3LYP/6-31G(d) level of theory. The electronic absorption and emission spectra of the BDP molecular structure in ethanol solvent were calculated using time-dependent density functional theory (TDDFT) at CAM-B3LYP/6-31G +  + (d, p) level. The obtained theoretical results were compared to experimental ones.


Chemosphere ◽  
2021 ◽  
pp. 131994
Author(s):  
Mingxuan Jia ◽  
Boyu Jia ◽  
Xiaofang Liao ◽  
Linchun Shi ◽  
Zheng Zhang ◽  
...  

2021 ◽  
Author(s):  
Rahman Hallaj ◽  
Zahra Hosseinchi

Abstract This work focuses on the synthesis of novel modified core-shell CdTe/CdS quantum dots (QDs) and develops as a fluorescence sensor for glucose determination. The (E)-2,2'-(4,4'-dioxo-2,2'-dithioxo-2H,2'H-[5,5'-bithiazolylidene]-3,3'(4H,4'H)-diyl)bis(3- mercaptopropanoic acid) (DTM) as a new derivative of thiazolidine was synthesized and characterized and used to surface-modification of CdTe/CdS QDs. DTM-capped CdTe/CdS QDs used to immobilization of glucose oxidase (GOD). The intensity fluorescence emission of the CdSe/CdS-DTM/GOD is highly sensitive to the concentration of H2O2 as a byproduct of the catalytic oxidation of glucose. The experimental results showed that the quenched fluorescence was proportional to the glucose concentration within the range of 10 nM − 0.32 µM under optimized experimental conditions. The limit of detection of this system was found to be 4.3 nM. Compared with most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, and good sensitivity.


2021 ◽  
pp. 2102690
Author(s):  
Fengliang Wang ◽  
Tingting Hou ◽  
Xin Zhao ◽  
Wen Yao ◽  
Ruiqi Fang ◽  
...  

Author(s):  
Necip Öcal ◽  
Ahmet Ceylan ◽  
Fatih Duman

Background: Intracellular biosynthesis of quantum dots (QDs) based on microorganisms offers a green alternative and eco-friendly for the production of nanocrystals with superior properties. This study focused on the production of intracellular CdS QDs by stimulating the detoxification metabolism of Pseudomonas aeruginosa. Methods: For this aim, Pseudomonas aeruginosa ATCC 27853 strain was incubated in a solution of 1mM cadmium sulphate (CdSO4) to manipulate the detoxification mechanism. The intracellularly formed Cd-based material was extracted, and its characterization was carried out by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and dynamic light scattering (DLS) analyses and absorption-emission spectra. Results: The obtained material showed absorption peaks at 385 nm and a luminescence peak at 411 nm, and the particle sizes were measured in the range 4.63-17.54 nm. It was determined that the material was sphere-shaped, with a cubic crystalline structure, including Cd and S elements. The agar disk diffusion method investigated the antibacterial and antifungal activities of CdS QDs against eleven bacterial (four Gram-positive and seven Gram-negative) and one fungal strain. It was revealed that the obtained material has antibacterial effects on both Gram-positive and Gram-negative bacteria. However, cleavage activity of CdS QDs on pBR322 DNA was not detected. Conclusion: As a result, it has been proposed that the stimulation of the detoxification mechanism can be an easy and effective way of producing green and cheap luminescent QDs or nanomaterial.


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