Characterization of in situ prepared nanocomposites of PS and TIO2nanoparticles surface modified with alkyl gallates: Effect of alkyl chain length

2013 ◽  
Vol 34 (3) ◽  
pp. 399-407 ◽  
Author(s):  
Enis S. Džunuzović ◽  
Jasna V. Džunuzović ◽  
Tijana S. Radoman ◽  
Milena T. Marinović-Cincović ◽  
Ljubiša B. Nikolić ◽  
...  
Keyword(s):  
Chain Length ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Alkyl Gallates ◽  
Surface Modified

scholarly journals The Inhibition of Uric Acid Formation Catalyzed by Xanthine Oxidase Properties of the Alkyl Caffeates and Cardol

2012 ◽  
Vol 1 (3) ◽  
pp. 257 ◽  
Author(s):  
Noriyoshi Masuoka ◽  
Ken-ichi Nihei ◽  
Takayoshi Masuoka ◽  
Kouhei Kuroda ◽  
Kenji Sasaki ◽  
...  
Keyword(s):  
Uric Acid ◽  
Xanthine Oxidase ◽  
Chain Length ◽  
Inhibitory Activity ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Acid Formation ◽  
Alkyl Gallates ◽  
Xanthine Oxidase Inhibitors ◽  
Specific Structural Feature

Xanthine oxidase inhibitors may serve as therapeutic agents for hyperuricaemia and/or oxidative stress. From our continuing investigation, we proposed that some inhibitors for reactions catalyzed by xanthine oxidase consisted of a head portion and a tail portion and that each portion had different functions for inhibition. In a previous study on the effect of alkyl gallates on the uric acid formation catalyzed by xanthine oxidase it was shown that the alkyl chain length needs to be longer than C<sub>6</sub> to exert inhibitory activity. In the current study, compounds having different head portions, alkyl caffeates, alkyl protocatechuates, alkyl 3,5-dihydroxybenzoates, 3,4- dihydroxyphenylalkanoates and 3,5-dihydroxyphenylalkanoates were prepared, and their effects on the uric acid formation were examined. A series of alkyl caffeates (C<sub>1</sub>-C<sub>10</sub>) was demonstrated effective in inhibiting the uric acid formation, and the inhibitory activity increased by increasing the alkyl chain length. However, none of the other compounds was effective in inhibiting the uric acid formation. These results indicate that head portions in these compounds are important for the inhibition of uric acid formation and require further a specific structural feature to elicit the inhibitory activity.

scholarly journals Properties of Polystyrene Clay Nanocomposites Prepared Using Two New Imidazolium Surfactants

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Giovanna Di Pasquale ◽  
Antonino Pollicino
Keyword(s):  
Infrared Spectroscopy ◽  
Chain Length ◽  
Polymer Matrix ◽  
Alkyl Chain ◽  
In Situ Polymerization ◽  
Alkyl Chain Length ◽  
Clay Nanocomposites ◽  
Uv Aging ◽  
Rheological Analysis

Montmorillonite/polystyrene nanocomposites were prepared by in situ photopolymerization of styrene in the presence of 2% by weight of clay organomodified by two new imidazolium surfactants having in their structure an alkyl chain with 20 or 22 carbon atoms, respectively. Thermogravimetry showed that the new surfactants are more thermally stable than conventional alkylammonium surfactants. The properties of the obtained nanocomposites were compared with those of pristine polystyrene, with those of a microcomposite obtained by in situ polymerization of styrene in the presence of unmodified clay, and with those of a nanocomposite obtained starting from an organomodified clay with a short alkyl chain (12 carbon atoms) imidazolium surfactant. XRD, TEM, and rheological analysis showed that the clay/PS nanocomposites have a mixture of intercalated and partially exfoliated structure layers, where the higher the surfactant alkyl chain length, the higher the exfoliation degree. Kinetics curve of accelerated UV aging, obtained by following through infrared spectroscopy the increase of carbonyl functions during aging, showed that the rate of photooxidation of clay containing samples is higher than neat polystyrene. The rate is higher as a function of the degree of dispersion of the filler in the polymer matrix.

scholarly journals Silver Nanoparticles Stabilized with Phosphorus-Containing Heterocyclic Surfactants: Synthesis, Physico-Chemical Properties, and Biological Activity Determination

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1883
Author(s):  
Martin Pisárčik ◽  
Miloš Lukáč ◽  
Josef Jampílek ◽  
František Bilka ◽  
Andrea Bilková ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Biological Activity ◽  
Zeta Potential ◽  
Chain Length ◽  
Alkyl Chain ◽  
Chemical Properties ◽  
Alkyl Chain Length ◽  
Microbial Pathogens ◽  
Physico Chemical ◽  
Phosphorus Containing

Phosphorus-containing heterocyclic cationic surfactants alkyldimethylphenylphospholium bromides with the alkyl chain length 14 to 18 carbon atoms were used for the stabilization of silver nanodispersions. Zeta potential of silver nanodispersions ranges from +35 to +70 mV, which indicates the formation of stable silver nanoparticles (AgNPs). Long-chain heptadecyl and octadecyl homologs of the surfactants series provided the most intensive stabilizing effect to AgNPs, resulting in high positive zeta potential values and smaller diameter of AgNPs in the range 50–60 nm. A comparison with non-heterocyclic alkyltrimethylphosphonium surfactants of the same alkyl chain length showed better stability and more positive zeta potential values for silver nanodispersions stabilized with heterocyclic phospholium surfactants. Investigations of biological activity of phospholium-capped AgNPs are represented by the studies of antimicrobial activity and cytotoxicity. While cytotoxicity results revealed an increased level of HepG2 cell growth inhibition as compared with the cytotoxicity level of silver-free surfactant solutions, no enhanced antimicrobial action of phospholium-capped AgNPs against microbial pathogens was observed. The comparison of cytotoxicity of AgNPs stabilized with various non-heterocyclic ammonium and phosphonium surfactants shows that AgNPs capped with heterocyclic alkyldimethylphenylphospholium and non-heterocyclic triphenyl-substituted phosphonium surfactants have the highest cytotoxicity among silver nanodispersions stabilized by the series of ammonium and phosphonium surfactants.

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