Study on the Photoluminescence Character of Water-Soluble CdSe Nanocrystals Under Ambient Conditions

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.

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Poly(allylamine)-Encapsulated Water-Soluble CdSe Nanocrystals

The Journal of Physical Chemistry B ◽

10.1021/jp0603841 ◽

2007 ◽

Vol 111 (1) ◽

pp. 81-87 ◽

Cited By ~ 12

Author(s):

Jeunghoon Lee ◽

Baocheng Yang ◽

Rongfu Li ◽

Thomas A. P. Seery ◽

Fotios Papadimitrakopoulos

Keyword(s):

Water Soluble ◽

Cdse Nanocrystals

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Direct Synthesis of Bimetallic Nanoalloys from Corresponding Bulk Alloys

MRS Proceedings ◽

10.1557/opl.2013.632 ◽

2013 ◽

Vol 1546 ◽

Author(s):

Chi-Kai Lin ◽

Tao Xu

Keyword(s):

Ag Nanoparticles ◽

Direct Synthesis ◽

Water Soluble ◽

Liquid Lithium ◽

Proof Of Concept ◽

Ambient Conditions ◽

X Ray Diffraction ◽

Bimetallic Alloy ◽

Transmission Electron ◽

Bulk Alloys

AbstractWe report a transformative, all inorganic method-based synthesis of supported bimetallic alloy nanoparticles. We use Pd3Ag as a proof of concept. The method involves breaking down bulk Pd3Ag alloy into the nanoparticles in liquid lithium, converting metallic Li to LiOH, transferring Pd3Ag nanoparticles/LiOH mixture onto non-water soluble supports, followed by leaching off the LiOH with water under ambient conditions. The size of the resulting Pd3Ag nanoparticles was found narrowly distributed around 2.3 nm characterized by transmission electron microscope (TEM). In addition, studies by X-ray diffraction (XRD) showed that the resulting Pd3Ag nanoparticles inherited similar structure as the starting bulk Pd3Ag.

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A review of current knowledge concerning PM<sub>2.5</sub> chemical composition, aerosol optical properties, and their relationships across China

10.5194/acp-2017-271 ◽

2017 ◽

Cited By ~ 2

Author(s):

Jun Tao ◽

Leiming Zhang ◽

Junji Cao ◽

Renjian Zhang

Keyword(s):

Optical Properties ◽

Chemical Composition ◽

Current Knowledge ◽

Northern China ◽

Water Soluble ◽

Chemical Components ◽

Carbonaceous Aerosols ◽

Ambient Conditions ◽

Aerosol Optical Properties ◽

Inorganic Aerosols

Abstract. To obtain a thorough knowledge of PM2.5 chemical composition and its impact on aerosol optical properties across China, existing field studies conducted after the year of 2000 are reviewed and summarized in terms of geographical, inter-annual, and seasonal distributions. Annual PM2.5 was up to six times of the national air quality standard in some megacities in northern China. Annual PM2.5 was higher in northern than southern cities, and higher in inland than coastal cities. In a few cities with data longer than a decade, PM2.5 showed a slight decrease only in the second half of the past decade, while carbonaceous aerosols decreased, sulfate (SO42−) and ammonium (NH4+) remained at high levels, and nitrate (NO3−) increased. The highest seasonal averages of PM2.5 and its major chemical components were mostly observed in the cold seasons. Annual average contributions of secondary inorganic aerosols to PM2.5 ranged from 25 % to 48 %, and those of carbonaceous aerosols ranged from 23 % to 47 %, both with higher values in southern regions due to the frequent dust events in northern China. The geographical pattern of scattering coefficient (bsp) was similar to that of PM2.5, and that of aerosol absorption coefficient (bap) was determined by elemental carbon (EC) mass concentration and its coating. bsp in ambient condition of RH = 80 % can be amplified about 1.8 times of that under dry condition. Secondary inorganic aerosols accounted for about 60 % of aerosol extinction coefficient (bext) under ambient conditions in megacities with RH higher than 70 %. The mass scattering efficiency (MSE) of PM2.5 ranged from 3.0 to 5.0 m2 g−1 for aerosols produced from anthropogenic emissions and from 0.7 to 1.0 m2 g−1 for natural dust aerosols. The mass absorption efficiency (MAE) of EC ranged from 6.5 to 12.4 m2 g−1 in urban environments, but the MAE of water-soluble organic carbon (WSOC) was only 0.05 to 0.11 m2 g−1. Historical emission control policies in China and their effectiveness were discussed based on available chemically resolved PM2.5 data, which provides the much-needed knowledge for guiding future studies and emission policy making.

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

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18168 ◽

2008 ◽

Vol 8 (3) ◽

pp. 1178-1182 ◽

Cited By ~ 2

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.

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Synthesis of water-soluble luminescent poly(acrylic acid)-encapsulated CdTe/CdS nanoparticles

Canadian Journal of Chemistry ◽

10.1139/cjc-2013-0363 ◽

2014 ◽

Vol 92 (1) ◽

pp. 54-57 ◽

Cited By ~ 3

Author(s):

Jane Betty Goh ◽

Richard W. Loo ◽

M. Cynthia Goh

Keyword(s):

Acrylic Acid ◽

Quantum Dot ◽

Water Soluble ◽

Cds Nanoparticles ◽

Ambient Conditions ◽

Poly Acrylic Acid

Described is the synthesis in water under ambient conditions of water-soluble, luminescent poly(acrylic acid)-encapsulated CdTe/CdS nanoparticles. Counterion-collapsed poly(acrylic acid) is used as a nanotemplate for the formation of the quantum dot core. Gram quantities of nanoparticles are easily obtained. Simply varying the amount of thioacetamide used in the synthesis can shift the emission wavelengths of the resulting nanoparticles from green to yellow to red.

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Biocatalysis for Material Science and Drug Discoveries

MRS Proceedings ◽

10.1557/proc-1065-qq01-06 ◽

2007 ◽

Vol 1065 ◽

Author(s):

Ferdinando Francesco Bruno ◽

Lynne A Samuelson ◽

Subhalakshmi Nagarajan ◽

Ramaswamy Nagarajan ◽

Jayant Kumar

Keyword(s):

Epithelial Cell ◽

Cancer Cells ◽

Water Solubility ◽

Human Cancer ◽

Water Soluble ◽

Ambient Conditions ◽

Inhibitory Effects ◽

One Pot ◽

Growth Inhibitory ◽

Soluble Poly

ABSTRACTA novel biomimetic route for the synthesis of conducting homopolymers and copolymers from aniline, phenol, pyrrole and 3,4-ethylenedioxy-thiophene in the presence of a polyelectrolyte, such as polystyrene sulfonate (SPS) is presented. A poly(ethylene glycol) modified hematin (PEG-Hematin) and the enzyme horseradish peroxidase (HRP) were used to catalyze the copolymerization of different monomers. UV-vis, FTIR, XPS, TGA and electrical conductivity studies for all complexes indicated the presence of a stable and electrically conductive form of these polymers. Furthermore, the presence of a polyelectrolyte, such as SPS, in this complex provides a unique combination of properties such as processability and water-solubility. Additionally catechins, the active compounds found in green tea, were polymerized and found to exhibit very interesting anti-carcinogenic properties. Here we report a unique enzymatic approach for the synthesis of water-soluble poly(catechins) with enhanced stability and potent anti-proliferative effects on human cancer cells in vitro. Various stereoisomers of catechin [(+), (-), (±)] and (-)-epicatechin have been biocatalytically polymerized using HRP in ethanol/buffer mixtures. This one-pot biocatalytic polymerization is carried out in ambient conditions yielding water-soluble poly(catechins). These synthesized poly(catechins) were tested for their growth inhibitory properties using a variety of normal and cancerous human epithelial cell lines. The poly(catechins) exhibit statistically significant greater growth inhibitory effects when compared to the monomers and exhibited specificity, inhibiting the growth of breast, colorectal and esophageal cancer cells while having little effect on normal epithelial cell growththus achieving a high therapeutic ratio. The synthesis, characterization and the growth inhibitory effects of these novel water-soluble poly(catechins) will also be presented.

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Rice Husk-Derived Cellulose Nanofibers: A Potential Sensor for Water-Soluble Gases

Sensors ◽

10.3390/s21134415 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4415

Author(s):

Naresh Shahi ◽

Eunji Lee ◽

Byungjin Min ◽

Dong-Joo Kim

Keyword(s):

Recovery Time ◽

Low Cost ◽

Cellulose Nanofibers ◽

High Sensitivity ◽

Water Soluble ◽

Sensor Technology ◽

Good Sensitivity ◽

Ambient Conditions ◽

Sensing Material ◽

Study Results

Cellulose and its derivatives have evoked much attention in sensor technology as host-matrices for conducting materials because of their versatility, renewability, and biocompatibility. However, only a few studies have dealt with the potential utilization of cellulose as a sensing material without a composite structure. In this study, cellulose nanofibers (CNF) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNF) extracted from rice husks by using ultrasonic-assisted methods are introduced as a potential gas sensing material with highly sensitive performance. To fabricate nanocellulose-based films, CNF, TOCNF, and TOCNF with glycerol (TOCNF/G) were dispersed in water and applied on polyimide substrate with digital electrodes to form self-standing thin films by a drop-casting method. A transparent coating layer on the surface of the plate after drying is used for the detection of water-soluble gases such as acetone, ammonia, methane, and hydrogen sulfide gases at room temperature at 52% relative humidity. The sensor prototypes exhibited high sensitivity, and the detection limit was between 1 ppm and 5 ppm, with less than 10 min response and recovery time. The results indicate that both the CNF- and the TOCNF-coated sensors show good sensitivity toward ammonia and acetone, compared to other gases. A TOCNF/G-coated sensor exhibited minimum time in regard to response/recovery time, compared to a CNF-coated sensor. In this study, nanocellulose-based sensors were successfully fabricated using a low-cost process and a bio-based platform. They showed good sensitivity for the detection of various gases under ambient conditions. Therefore, our study results should further propel in-depth research regarding various applications of cellulose-based sensors in the future.

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Biomimetic models of nitric oxide synthase for the oxidation of oximes to carbonyl compounds catalyzed by water-soluble manganese porphyrins in aqueous solution

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424611003173 ◽

2011 ◽

Vol 15 (03) ◽

pp. 211-216 ◽

Cited By ~ 4

Author(s):

Qing-Gang Ren ◽

Xian-Tai Zhou ◽

Hong-Bing Ji

Keyword(s):

Carbonyl Compounds ◽

Water Soluble ◽

Ambient Conditions ◽

Manganese Porphyrin ◽

Manganese Porphyrins ◽

Vis Spectroscopy ◽

Excellent Activity ◽

High Valent ◽

Manganese Species ◽

Oxide Synthase

A mild green and efficient approach for hydrogen peroxide oxidative converting oximes to the corresponding carbonyl compounds with a water-soluble manganese porphyrin as catalyst in water/acetone mixture has been developed. The water-soluble manganese porphyrin showed an excellent activity for the oxidative deoximation reactions of various oximes under ambient conditions in the absence of any additive. The oxidative deoximation was through the formation of high valent oxo-manganese species, which was confirmed by in situ UV-vis spectroscopy.

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