Aqueous Processing CdSe/TGA Quantum dots For Potential Bio-Medical Applications

2015 ◽  
Vol 1797 ◽  
Author(s):  
Raquel Feliciano-Crespo ◽  
José A Rodriguez-Gonzalez ◽  
Chuan-Jian Zhong ◽  
Oscar Perales-Perez
Keyword(s):  
Optical Properties ◽  
Crystallite Size ◽  
Hexagonal Structure ◽  
Water Soluble ◽  
Visible Range ◽  
Cdse Nanocrystals ◽  
Excitation Wavelength ◽  
Exciton Peak ◽  
Cdse Qds ◽  
E Coli

ABSTRACTThe size-dependent optical properties of CdSe nanoparticles are desirable in bio-imaging and cell sorting applications because of their tunable photoluminescence in the visible range. Previous studies have already suggested that CdSe QDs could be utilized for pathogen detection by using suitable capping agents to make it biocompatible; however, systematic works on the effect of crystallite size and composition of the nanocrystals are scarce. The present research will be focused on the effect of CdSe crystal size and composition (pure and doped systems) to systematically evaluate its applicability in detecting pathogens, like Escherichia coli (E. coli). Highly luminescent water-soluble CdSe QDs were firstly synthesized in the aqueous phase, in the presence of thioglycolic acid (TGA) as a capping agent. CdSe/TGA molar ratios, reaction temperature, time, and pH were evaluated in order to optimizer the QDs optical properties. X-Ray diffraction (XRD) measurements confirmed the formation of CdSe exhibiting hexagonal structure with an estimated averaged crystallite size in the 4-6 nm range. Transmission electron microscopy (TEM) analyses evidenced the formation of CdSe nanocrystals with particle sizes between 3-5 nm. UV-Vis measurements showed a strong exciton peak between 390-400 nm with an estimated band gap of 2.64 eV (bulk: 1.74 eV); additionally, a strong fluorescence peak was observed between 500-550 nm using an excitation wavelength of 400 nm. Fourier Transform Infrared Spectroscopy (FT-IR) analyses suggested the actual functionalization of the CdSe surface with TGA functional groups. Preliminary results of the CdSe/TGA coupling with the selected bacteria, E. coli, are presented and discussed.

Synthesis and Optical Properties of L-Cysteine Hydrochloride-Stabilized CdSe Nanocrystals in a New Alkali System

2008 ◽  
Vol 8 (3) ◽  
pp. 1178-1182 ◽  
Author(s):  
Bin Feng ◽  
Feng Teng ◽  
Ai-Wei Tang ◽  
Yan Wang ◽  
Yan-Bing Hou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Nanocrystals ◽  
X Ray ◽  
Transmission Electron ◽  
Cysteine Hydrochloride

Water-soluble CdSe nanocrystals were synthesized in a new alkali system at lower temperatures by using L-cysteine hydrochloride as a stabilizer and Na2SeSO3 as a selenium source to enable the synthesis of CdSe nanocrystals in a wider range of pHvalues. The CdSe nanocrystal powder was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. We systematically investigated the effect of synthesis conditions on the optical properties of the L-cysteine hydrochloride-stabilized CdSe nanocrystals, and found that different sizes of CdSe nanocrystals can be obtained by changing the pHvalue, the molar ratio of L-cysteine hydrochloride to Cd2+, or the refluxing time. The emission maxima of the obtained CdSe nanocrystals can be tuned in a wider range from 477 to 575 nm by changing the pHvalue from 7 to 13. We observed an obvious blue-shift of the absorption and photoluminescence peak position by varying the molar ratio of L-Cys to Cd2+ from 3.5:1 to 2:1 at the same pHvalue. The size of the obtained nanocrystals increased and the full width at half maximum became narrower as reflux time increased. Transmission electron microscopy images indicate that the as-prepared CdSe nanocrystals have a good dispersion, which means that L-cysteine hydrochloride can control the grouping of CdSe nanocrystals excellently as a stabilizer in the new alkali system.

scholarly journals Raman Stable Isotope Probing of Bacteria in Visible and Deep UV-Ranges

Life ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1003
Author(s):  
Georgette Azemtsop Matanfack ◽  
Aikaterini Pistiki ◽  
Petra Rösch ◽  
Jürgen Popp
Keyword(s):  
Stable Isotope ◽  
Resonance Raman Spectroscopy ◽  
Stable Isotope Probing ◽  
Visible Range ◽  
Excitation Wavelength ◽  
Bacterial Cells ◽  
E Coli ◽  
Efficient Detection ◽  
Uv Resonance Raman Spectroscopy ◽  
Deep Uv

Raman stable isotope probing (Raman-SIP) is an excellent technique that can be used to access the overall metabolism of microorganisms. Recent studies have mainly used an excitation wavelength in the visible range to characterize isotopically labeled bacteria. In this work, we used UV resonance Raman spectroscopy (UVRR) to evaluate the spectral red-shifts caused by the uptake of isotopes (13C, 15N, 2H(D) and 18O) in E. coli cells. Moreover, we present a new approach based on the extraction of labeled DNA in combination with UVRR to identify metabolically active cells. The proof-of-principle study on E. coli revealed heterogeneities in the Raman features of both the bacterial cells and the extracted DNA after labeling with 13C, 15N, and D. The wavelength of choice for studying 18O- and deuterium-labeled cells is 532 nm is, while 13C-labeled cells can be investigated with visible and deep UV wavelengths. However, 15N-labeled cells are best studied at the excitation wavelength of 244 nm since nucleic acids are in resonance at this wavelength. These results highlight the potential of the presented approach to identify active bacterial cells. This work can serve as a basis for the development of new techniques for the rapid and efficient detection of active bacteria cells without the need for a cultivation step.

scholarly journals Facile Synthesis of Water-Soluble, Highly-Fluorescent Graphene Quantum Dots from Graphene Oxide Reduction for Efficient Cell Labelling

2019 ◽  
Vol 5 (4) ◽  
pp. 77 ◽  
Author(s):  
Minati ◽  
Del Piano
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Network Formation ◽  
Graphene Quantum Dots ◽  
Water Soluble ◽  
Visible Range ◽  
Cell Labelling ◽  
Excitation Wavelength ◽  
Residual Solvent

In this work, we report a simple, one-step, green procedure to fabricate strong blue and yellow photoluminescent graphene quantum dots (GQDs) as by-product of the synthesis of mesoporous graphene hydrogel (GHs). The graphene hydrogel was obtained by chemical reduction of graphene oxide using ascorbic acid at mild temperature. As a consequence of the network formation, small fluorescent GQDs can be isolated from the residual solvent, purified from the by-products and finally concentrated to produce GQDs. The GQDs chemistry and morphology were characterized by X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The GQDs mean diameter was about 5–10 nm and they exhibited an intense luminescence in the visible range with an excitation wavelength-dependent fluorescence. Our experiments showed that GQDs were easily internalized in living cells and furthermore, such internalization did not adversely affect cell viability.

scholarly journals Fabrication of Transparent Mg(OH)2 Thin Films by Drop-Dry Deposition

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 724
Author(s):  
Tong Li ◽  
Masaya Ichimura
Keyword(s):  
Thin Films ◽  
Aqueous Solution ◽  
Optical Properties ◽  
Surface Morphology ◽  
Magnesium Hydroxide ◽  
Dry Deposition ◽  
Visible Range ◽  
Substrate Heating ◽  
Water Effects ◽  
Deposition Conditions

Magnesium hydroxide (Mg(OH)2) thin films were deposited by the drop-dry deposition (DDD) method using an aqueous solution containing Mg(NO3)2 and NaOH. DDD was performed by dropping the solution on a substrate, heating-drying, and rinsing in water. Effects of different deposition conditions on the surface morphology and optical properties of Mg(OH)2 thin films were researched. Films with a thickness of 1−2 μm were successfully deposited, and the Raman peaks of Mg(OH)2 were observed for them. Their transmittance in the visible range was 95% or more, and the bandgap was about 5.8 eV. It was found that the thin films have resistivity of the order of 105 Ωcm. Thus, the transparent and semiconducting Mg(OH)2 thin films were successfully prepared by DDD.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

Inhibition of ATPase activity of E. coli F1 by the water-soluble carbodiimide EDC is due to modification of several carboxyls in the .beta. subunit

Biochemistry ◽  
1984 ◽  
Vol 23 (18) ◽  
pp. 4134-4140 ◽  
Author(s):  
Hans Ruedi Lotscher ◽  
Catherina DeJong ◽  
Roderick A. Capaldi
Keyword(s):  
Atpase Activity ◽  
Water Soluble ◽  
Beta Subunit ◽  
E Coli

Pyridine-based poly(aryleneethynylene)s: a study on anionic side chain density and their influence on optical properties and metallochromicity

RSC Advances ◽  
2015 ◽  
Vol 5 (116) ◽  
pp. 96189-96193 ◽  
Author(s):  
Markus Bender ◽  
Kai Seehafer ◽  
Marlene Findt ◽  
Uwe H. F. Bunz
Keyword(s):  
Optical Properties ◽  
Water Soluble ◽  
Side Chain ◽  
Phenylene Ethynylene ◽  
Alternating Copolymers

We report the Pd-catalyzed synthesis of six new water soluble, alternating poly(p-phenylene-ethynylene-p-pyridinylene-ethynylene) (abcb-alternating) copolymers and one poly(p-pyridinyleneethynylene).

Influence of Bi2O3 on Borophosphate Glasses Properties

2014 ◽  
Vol 979 ◽  
pp. 343-346 ◽  
Author(s):  
Natthakridta Chanthima ◽  
Jakrapong Kaewkhao
Keyword(s):  
Optical Properties ◽  
Molar Volume ◽  
Absorption Spectra ◽  
Packing Density ◽  
Visible Range ◽  
Melt Quenching ◽  
Borophosphate Glasses ◽  
Borophosphate Glass ◽  
Uv Visible

Borophosphate glasses have been synthesized with a Bi2O3concentration of 15.0 to 25.0 mol%, added 2.5 mol% for each concentration, by the normal melt quenching technique at 1200 °C. The physical and optical properties of bismuth borophosphate glass systems have been studied. The glasses are characterized for their physical and optical properties. The density and molar volume of these glasses were found in the range 3.4391 to 3.9338 g/cm3and 52.2515 to 55.7557 cm3/mol, respectively. It was observed that the density and molar volume of these glasses was increased with increasing the concentration of Bi2O3. The absorption spectra of these glasses were recorded in the UV-Visible range. It has been found that, the absorption spectra were shifted to longer wavelength with higher Bi2O3concentration. In addition, the oxygen packing density of glass samples have been also investigated.

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