Water-soluble gold nanoclusters with pH-dependent fluorescence and high colloidal stability over a wide pH range via co-reduction of glutathione and citrate

RSC Advances ◽  
2014 ◽  
Vol 4 (43) ◽  
pp. 22651-22659 ◽  
Author(s):  
Wenchao Ding ◽  
Yong Liu ◽  
Yijing Li ◽  
Qiurong Shi ◽  
Houshen Li ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Colloidal Stability ◽  
Gold Nanoclusters ◽  
Water Soluble ◽  
Simple Strategy ◽  
Wide Ph Range ◽  
Ph Dependent ◽  
Ph Range ◽  
Co Reduction

We present a simple strategy for synthesis of water-soluble, monodisperse, highly fluorescent gold nanoclusters (Au NCs) with sizes of 1.8 nm by co-reduction of glutathione and citrate for 24 h at 50 °C. The fluorescence intensity of the GS/C–Au NCs obtained is pH-dependent and can be reversibly adjusted in the pH range from 4.1 to 8.6.

Use of bentonite to control the release of copper from contaminated soils

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 618 ◽  
Author(s):  
Wanting Ling ◽  
Qing Shen ◽  
Yanzheng Gao ◽  
Xiaohong Gu ◽  
Zhipeng Yang
Keyword(s):  
Heavy Metals ◽  
Sorption Capacity ◽  
Contaminated Soils ◽  
Montmorillonite Clay ◽  
Maximum Sorption Capacity ◽  
Maximum Sorption ◽  
Wide Ph Range ◽  
Ph Dependent ◽  
Ph Range ◽  
Soil Ageing

A decrease in release and availability of heavy metals in soil has been of worldwide interest in recent years. Bentonite is a type of expandable montmorillonite clay, and has strong sorption for heavy metals. In this work, the control of amended bentonite on the release of copper (Cu2+) from spiked soils was investigated using a batch equilibrium technique. Sorption of Cu by bentonite was pH-dependent, and could be well described using the Langmiur model. Maximum sorption capacity of the bentonite used in this study was 5.4 mg/g, which was much greater than soils reported in the literature. The extent of Cu2+ release from spiked soils was correlated with slurry concentrations, pH, and soil ageing process. In all cases, the amendment of bentonite was observed to effectively decrease the release of Cu2+ from soils. The apparent aqueous concentrations of Cu2+ released from soils devoid of bentonite treatment were 113–1160% higher than those from the soils amended with bentonite. Moreover, the magnitude of Cu2+ release decreased with increasing amount of bentonite added to soils. The bentonite added was more effective in retaining Cu2+ in sorbents for aged contaminated soils. Such enhanced retention resulting from the presence of bentonite was observed within a wide pH range from 2.5 to 7.0. Bentonite, as one of the most abundant minerals in soils, is regarded to improve the soil overall quality. The results obtained from this work provide useful information on utilisation of bentonite to control the release of heavy metals from contaminated soils.

scholarly journals Synthesis of water-soluble chitosan for biomedical applications

2015 ◽  
Vol 18 (3) ◽  
pp. 170-180
Author(s):  
Anh Thi Tram Tu ◽  
Huy Thuc Ha
Keyword(s):  
Drug Delivery ◽  
Molecular Weight ◽  
Iron Oxide ◽  
Biomedical Applications ◽  
Drug Delivery Systems ◽  
Water Soluble ◽  
Oxide Nanoparticles ◽  
Wide Ph Range ◽  
Ft Ir ◽  
Ph Range

Highly deacetylated chitosan (CS) reacted with anhydride acetic (Ac2O) to produce chitosan with various degree of deacetylation (DDA) depending on the CS/Ac2O ratios. The structure of products was characterized by FT-IR, 1H NMR, 13C NMR, and the molecular weight was identified by GPC. The DDA of products decreases as the CS/Ac2O ratio increases. The products with less than 80 % DDA were soluble in water with a wide pH range. The water-soluble chitosan can be used in many biomedical applications such as manufacturing drug delivery systems or functionalized iron oxide nanoparticles.

Hydrothermally treated chitosan spontaneously forms water-soluble spherical particles stable at a wide pH range

2016 ◽  
Vol 65 (15) ◽  
pp. 751-758 ◽  
Author(s):  
Srijita Basumallick ◽  
Maria Gabriela Nogueira Campos ◽  
David Richardson ◽  
Andre Gesquiere ◽  
Swadeshmukul Santra
Keyword(s):  
Water Soluble ◽  
Spherical Particles ◽  
Wide Ph Range ◽  
Ph Range

Receptors for sulfate that function across a wide pH range in mixed aqueous–DMSO media

2019 ◽  
Vol 55 (82) ◽  
pp. 12312-12315 ◽  
Author(s):  
Lei Qin ◽  
James R. Wright ◽  
Jakob D. E. Lane ◽  
Stuart N. Berry ◽  
Robert B. P. Elmes ◽  
...  
Keyword(s):  
Water Soluble ◽  
Aqueous Dmso ◽  
Wide Ph Range ◽  
Ph Range

Water soluble macrocyclic squaramides bind selectively to sulfate in aqueous–DMSO mixtures across a pH range from 3.2–14.

Effect of pH on the cation exchange capacity of some halloysite nanotubes

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Nia Gray ◽  
David G. Lumsdon ◽  
Stephen Hillier
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Halloysite Nanotubes ◽  
Exchange Capacity ◽  
Average Value ◽  
Two Samples ◽  
Wide Ph Range ◽  
Capacitance Model ◽  
Ph Dependent ◽  
Ph Range

AbstractThe cation exchange capacity (CEC) of seven well characterized halloysite nanotubes (HNTs) in the dehydrated 7 Å form has been measured using a method based on cobalt hexammine exchange. In addition to unbuffered measurements, which varied between 2.9 and 9.3 cmol(+)kg−1, CECs were also determined over a wide pH range and proton titration measurements were conducted on two samples. The data were fitted using a constant capacitance model based on the presence of two sites: permanently charged sites and pH-dependent variable charged sites. Normalization of CEC to the average specific surface area (BET) of the halloysite samples reduces considerably the variation of CEC values for the different samples particularly over the intermediate pH range (5–9) with the average value at pH 7 equal to 8.5 cmol(+)kg−1and a standard deviation of 1.17. Overall the CEC behaviour of the seven samples appears reasonably consistent throughout the set. Calculations based on proton titrations suggest a ratio of variable charge to basal sites for the dehydrated halloysite nanotubes of ∼3:1.

scholarly journals d-, l- and d,l-Tryptophan-Based Polyamidoamino Acids: pH-Dependent Structuring and Fluorescent Properties

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 543 ◽  
Author(s):  
Federica Lazzari ◽  
Amedea Manfredi ◽  
Jenny Alongi ◽  
Daniele Marinotto ◽  
Paolo Ferruti ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Water Soluble ◽  
Photoluminescence Properties ◽  
Fluorescent Properties ◽  
Acid Base ◽  
Scattering Measurements ◽  
Tryptophan Content ◽  
Ph Dependent ◽  
Ph Range ◽  
Glycine Content

Chiral polyamidoamino acids were obtained by polyaddition of N,N’-methylenebisacrylamide with d-, d,l- and l-tryptophan (M-d-Trp, M-d,l-Trp and M-l-Trp). l-tryptophan/glycine copolymers, M-G-l-Trp5, M-G-l-Trp10, M-G-l-Trp20 and M-G-l-Trp40, were prepared from l-tryptophan/glycine mixtures. These polymers were amphoteric, with acid-base properties similar to those of the parent amino acids. The l-tryptophan/glycine copolymers with high glycine content were water soluble in the pH range 2-12. M-G-l-Trp40 showed a solubility gap centred at pH 4.5 and all tryptophan homopolymers were soluble only at pH > 7. Dynamic light scattering measurements performed in their solubility ranges, namely 2-11 M-G-l-Trp5, M-G-l-Trp10 and M-G-l-Trp20 and 7-11 for M-G-l-Trp40, M-d-Trp, M-l-Trp and M-d,l-Trp, showed that the size of all samples did not significantly vary with pH. Both M-l-Trp and M-G-l-Trp copolymers showed pH-dependent circular dichroism spectra in the wavelength interval 200–280 nm, revealing structuring. All samples were fluorescent. Their emission spectra were unstructured and, if normalized for their tryptophan content, almost superimposable at the same pH, providing evidence that only tryptophan governed the photoluminescence properties. Changing pH induced in all cases a slight shift of the emission wavelength maximum ascribed to the modification of the microenvironment surrounding the indole ring induced by different protonation degrees.

scholarly journals Self-Assembled Multilayers and Photoluminescence Properties of a New Water-Soluble Poly(Para-Phenylene)

1997 ◽  
Vol 488 ◽  
Author(s):  
Xiaobo Shi ◽  
DeQuan Li ◽  
M. Lütt ◽  
M. R. Fitzsimmons ◽  
G. P. Van Patten
Keyword(s):  
Uv Light ◽  
Water Soluble ◽  
Solubility In Water ◽  
Dimethyl Ammonium ◽  
Wide Ph Range ◽  
Dilute Aqueous Solutions ◽  
Self Assembled ◽  
Ph Range ◽  
Positively Charged ◽  
Soluble Poly

AbstractThis paper reports the synthesis and characterizations of a new water-soluble poly(paraphenylene) (PPP) and its applications in preparing self-assembled multi-layer films. This new water-soluble conducting polymer was prepared through the sulfonation reaction of poly(pquarterphenylene- 2,2'-dicarboxylic acid). The incorporation of sulfonate groups has dramatically improved PPP's solubility in water at a wide pH range, whereas previous PPP is only slightly soluble in basic solutions. Dilute aqueous solutions of this polymer with acidic, neutral or basic pH emit brilliant blue light while irradiated with UV light. The sulfonated PPP emits from 350 nm to 455 nm with a maximum intensity at 380 nm. Self-assembled multilayers of this sulfonated PPP were constructed with a positively charged polymer poly(diallyl dimethyl ammonium chloride) and characterized with various surface analyses. Conductive (RuO2 and ITO), semiconductive (Si wafer), and non-conductive (SiO2) substrates were used in the preparation of self-assembled multilayers. Electrical, optical and structural properties of these novel self-assembled thin films will be discussed.

scholarly journals Oxygen- and pH-Dependent Photophysics of Fluorinated Fluorescein Derivatives: Non-Symmetrical vs. Symmetrical Fluorination

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5172
Author(s):  
Ciaran K. McLoughlin ◽  
Eleni Kotroni ◽  
Mikkel Bregnhøj ◽  
Georgios Rotas ◽  
Georgios C. Vougioukalakis ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Fluorescent Probe ◽  
Fluorescent Probes ◽  
Wide Ph Range ◽  
Ph Dependent ◽  
Ph Range ◽  
Derivatives Of

Fluorescein, and derivatives of fluorescein, are often used as fluorescent probes and sensors. In systems where pH is a variable, protonation/deprotonation of the molecule can influence the pertinent photophysics. Fluorination of the xanthene moiety can alter the molecule’s pKa such as to render a probe whose photophysics remains invariant over a wide pH range. Di-fluorination is often sufficient to accomplish this goal, as has been demonstrated with compounds such as Oregon Green in which the xanthene moiety is symmetrically difluorinated. In this work, we synthesized a non-symmetrical difluorinated analog of Oregon Green which we call Athens Green. We ascertained that the photophysics and photochemistry of Athens Green, including the oxygen-dependent photophysics that results in the sensitized production of singlet oxygen, O2(a1Δg), can differ appreciably from the photophysics of Oregon Green. Our data indicate that Athens Green will be a more benign fluorescent probe in systems that involve the production and removal of O2(a1Δg). These results expand the available options in the toolbox of fluorescein-based fluorophores.

A novel NhaD-type Na+/H+ antiporter from the moderate halophile and alkaliphile Halomonas alkaliphila

2017 ◽  
Vol 63 (7) ◽  
pp. 596-607 ◽  
Author(s):  
Yanhong Wang ◽  
Na Song ◽  
Lina Yang ◽  
Heba Abdel-motaal ◽  
Rui Zhang ◽  
...  
Keyword(s):  
Membrane Vesicles ◽  
Activity Profile ◽  
Moderate Halophile ◽  
E Coli ◽  
Significant Difference ◽  
Dependent Activity ◽  
Wide Ph Range ◽  
Ph Dependent ◽  
Ph Range ◽  
Selection Of

In this study, a NhaD-type Na+/H+ antiporter gene designated Ha-nhaD was obtained by selection of genomic DNA from the moderate halophile and alkaliphile Halomonas alkaliphila in Escherichia coli KNabc lacking 3 major Na+/H+ antiporters. The presence of Ha-NhaD conferred tolerance of E. coli KNabc to NaCl up to 0.6 mol·L–1 and to LiCl up to 0.2 mol·L–1 and to an alkaline pH. pH-dependent Na+(Li+)/H+ antiport activity was detected from everted membrane vesicles prepared from E. coli KNabc/pUC-nhaD but not those of KNabc/pUC18. Ha-NhaD exhibited Na+(Li+)/H+ antiport activity over a wide pH range from 7.0 to 9.5, with the highest activity at pH 9.0. Protein sequence alignment and phylogenetic analysis revealed that Ha-NhaD is significantly different from the 7 known NhaD-type Na+/H+ antiporters, including Dw-NhaD, Dl-NhaD, Vp-NhaD, Vc-NhaD, Aa-NhaD, He-NhaD, and Ha-NhaD1. Although Ha-NhaD showed a closer phylogenetic relationship with Ha-NhaD2, a significant difference in pH-dependent activity profile exists between Ha-NhaD and Ha-NhaD2. Taken together, Ha-nhaD encodes a novel pH-dependent NhaD-type Na+/H+ antiporter.

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