scholarly journals Cobalt(II), Zinc(II), Iron(III), and Copper(II) Complexes Bearing Positively Charged Quaternary Ammonium Functionalities: Synthesis, Characterization, Electrochemical Behavior, and SOD Activity

2020 ◽  
Vol 2020 (35) ◽  
pp. 3347-3358
Author(s):  
Marko Stojičkov ◽  
Sabrina Sturm ◽  
Božidar Čobeljić ◽  
Andrej Pevec ◽  
Mima Jevtović ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Quaternary Ammonium ◽  
Sod Activity ◽  
Positively Charged

scholarly journals Effects of Quaternary Ammonium Silane Coatings on Mixed Fungal and Bacterial Biofilms on Tracheoesophageal Shunt Prostheses

2006 ◽  
Vol 72 (5) ◽  
pp. 3673-3677 ◽  
Author(s):  
Janine J. H. Oosterhof ◽  
Kevin J. D. A. Buijssen ◽  
Henk J. Busscher ◽  
Bernard F. A. M. van der Laan ◽  
Henny C. van der Mei
Keyword(s):  
Silicone Rubber ◽  
Quaternary Ammonium ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Environmental Surfaces ◽  
Sprayed Coating ◽  
Tracheoesophageal Shunt ◽  
Positively Charged

ABSTRACT Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyldimethyloctadecylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF, was sprayed onto the silicone rubber surface. The sprayed coating lost its stability within an hour, while the chemically bonded coating appeared stable. Upon incubation in an artificial throat model, allowing simultaneous adhesion and growth of yeast and bacteria, all coated prostheses showed significant reductions in the numbers of viable yeast (to 12% to 16%) and bacteria (to 27% to 36%) compared with those for silicone rubber controls, as confirmed using confocal laser scanning microscopy after live/dead staining of the biofilms. In situ hybridization with fluorescently labeled oligonucleotide probes showed that yeasts expressed hyphae on the untreated and Biocidal ZF-coated prostheses but not on the QAS-coated prostheses. Whether this is a result of the positive QAS coating or is due to the reduced number of bacteria is currently unknown. In summary, this is the first report on the inhibitory effects of positively charged coatings on the viability of yeasts and bacteria in mixed biofilms. Although the study initially aimed at reducing voice prosthetic biofilms, its relevance extends to all biomedical and environmental surfaces where mixed biofilms develop and present a problem.

On the Electrochemical Behavior of Pyrylium Ions at the Mercury-Electrode. III. Adsorption Behavior at the Aqueous-Mercury Interface

1987 ◽  
Vol 40 (3) ◽  
pp. 579 ◽  
Author(s):  
WNC Garrard ◽  
FG Thomas
Keyword(s):  
Sulfuric Acid ◽  
Electrochemical Behavior ◽  
Mercury Electrode ◽  
Adsorbed Layer ◽  
Adsorption Behaviour ◽  
Vertical Orientation ◽  
Aqueous Mercury ◽  
Low Solubility ◽  
Monolayer Coverage ◽  
Positively Charged

The adsorption behaviour of four pyrylium ions-2,4,6-trimethylpyrylium, 2,4,6-tri-t- butylpyrylium , 2,4,6-triphenylpyrylium and 7-phenyl-5,6,8,9-tetrahydrodibenzo[ c,h ] xanthylium -at the mercury-aqueous 0.5 M sulfuric acid interface is reported. The 2,4,6-trimethylpyrylium ion shows little tendency to adsorb at the mercury interface even at concentrations approaching saturated solution. The tri-t- butylpyrylium ion is adsorbed in a vertical orientation on a positively charged electrode, while on a negatively charged electrode it exhibits two position adsorption- initially flat then reorienting to vertical at higher concentrations. Triphenylpyrylium ions form an adsorbed layer of vertically oriented ions which approaches monolayer coverage at potentials just prior to its reduction at -0.68 V. The product of the reduction inhibits the reduction of the parent ion. The xanthylium ion behaves in a similar manner to the tri-t-butyl ion but the conclusions are tentative due to the limited reliability of the data as a consequence of the low solubility of this ion in water.

scholarly journals Influence of calcium ions on physical chemical characteristics of semiconductor quantum dots encapsulated by amphiphilic polymer and their efficiency of cellular uptake

2020 ◽  
pp. 3-16
Author(s):  
Aliaksandra V. Radchanka ◽  
Tatiana I. Terpinskaya ◽  
Tatsiana L. Yanchanka ◽  
Tatjana V. Balashevich ◽  
Mikhail V. Artemyev
Keyword(s):  
Quantum Dots ◽  
Physicochemical Properties ◽  
Cellular Uptake ◽  
Calcium Ions ◽  
Quaternary Ammonium ◽  
Carboxyl Groups ◽  
Polymer Shell ◽  
Ζ Potential ◽  
Calcium Dependent ◽  
Positively Charged

Here, we studied the effect of calcium ions on the physicochemical properties and cellular uptake of CdSe/ZnS quantum dots encapsulated with poly(maleic anhydride-alt-1-tetradecene), modified to a varying extent by quaternary ammonium groups. It was shown that quantum dots carrying negatively charged carboxyl groups in the polymer shell change their physicochemical and optical characteristics in the presence of Ca2+ and Ba2+ ions. As the negatively charged carboxyl groups in the shell are completely replaced by positively charged quaternary ammonium groups, these effects gradually decrease. A change in the physicochemical properties of nanoparticles leads to a change in their cellular uptake in the presence of calcium ions. Nanoparticles carrying only negatively charged groups in the shell in the presence of Ca2+ agglomerate and form conglomerates of nanoparticles and cells. The positively charged quaternary ammonium groups in the polymer shell of the nanoparticles increase their aggregative stability in the presence of Ca2+ and contribute to their uptake by cells. The mechanisms of uptake depend on nanoparticle’s charge. Nanoparticles with a positive ζ potential are absorbed by calcium-dependent mechanisms, which are suppressed by inhibition of the calcium-dependent enzyme dynamin or in the presence of calcium chelator EGTA. The uptake of nanoparticles with a negative ζ potential, in contrast, is enhanced by the chelation of calcium ions. This indicates the different role of cellular calcium-dependent mechanisms in the uptake of positively and negatively charged nanoparticles.

Acute antihypertensive action of nitroxides in the spontaneously hypertensive rat

2006 ◽  
Vol 290 (1) ◽  
pp. R37-R43 ◽  
Author(s):  
Kinjal Patel ◽  
Yifan Chen ◽  
Kathryn Dennehy ◽  
Jonathan Blau ◽  
Stephanie Connors ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Spontaneously Hypertensive Rat ◽  
Antihypertensive Agents ◽  
Sod Activity ◽  
Hypotensive Action ◽  
Spontaneously Hypertensive ◽  
Antihypertensive Action ◽  
Hypertensive Rat ◽  
Antihypertensive Response ◽  
Positively Charged

Tempol is an amphipathic radical nitroxide (N) that acutely reduces blood pressure (BP) and heart rate (HR) in the spontaneously hypertensive rat (SHR). We investigated the hypothesis that the response to nitroxides is determined by SOD mimetic activity or lipophilicity. Groups ( n = 6–10) of anesthetized SHRs received graded intravenous doses of Ns: tempol (T), 4-amino-tempo (AT), 4-oxo-tempo (OT), 4-trimethylammonium-2,2,6,6-tetramethylpiperidine-1-oxyl iodide (CAT-1), 3-carbamoyl-proxyl (3-CP), or 3-carboxy-proxyl (3-CTPY). Others received native or liposomal (L) Cu/Zn SOD. T and OT are uncharged, AT is positively charged and cell-permeable, and CAT-1 is positively charged and cell-impermeable. 3-CP and 3-CTPY have five-member pyrrolidine rings, whereas T, AT, OT, and CAT-1 have six-member piperidine rings. T and AT reduced mean arterial pressure (MAP) similarly (−48 ± 2 mmHg and −55 ± 8 mmHg) but more ( P < 0.05) than OT and CAT-1. 3-CP and 3-CTPY were ineffective. The group mean change in MAP with piperidine Ns correlated with SOD activity ( r = −0.94), whereas their ED50 correlated with lipophilicity ( r = 0.89). SOD and L-SOD did not lower BP acutely but reduced it after 90 min (−32 ± 5 and −31 ± 6 mmHg; P < 0.05 vs. vehicle). Pyrrolidine nitroxides are ineffective antihypertensive agents. The antihypertensive response to piperidine Ns is predicted by SOD mimetic action, and the sensitivity of response is by hydrophilicity. SOD exerts a delayed hypotensive action that is not enhanced by liposome encapsulation, suggesting it must diffuse to an extravascular site.

Protamine-DNA interaction

1978 ◽  
Vol 36 (2) ◽  
pp. 200-201
Author(s):  
D.P. Bazett-Jones ◽  
F.P. Ottensmeyer
Keyword(s):  
Small Volume ◽  
Double Helix ◽  
Dna Interaction ◽  
Dark Field ◽  
Sperm Head ◽  
Nuclear Proteins ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dna Double Helix ◽  
Positively Charged

Dark field electron microscopy has been used for the study of the structure of individual macromolecules with a resolution to at least the 5Å level. The use of this technique has been extended to the investigation of structure of interacting molecules, particularly the interaction between DNA and fish protamine, a class of basic nuclear proteins of molecular weight 4,000 daltons.Protamine, which is synthesized during spermatogenesis, binds to chromatin, displaces the somatic histones and wraps up the DNA to fit into the small volume of the sperm head. It has been proposed that protamine, existing as an extended polypeptide, winds around the minor groove of the DNA double helix, with protamine's positively-charged arginines lining up with the negatively-charged phosphates of DNA. However, viewing protamine as an extended protein is inconsistent with the results obtained in our laboratory.

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