11 research outputs found
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Polyelectrolyte nanocontainers: controlled binding and release of indomethacin
Herein, polyelectrolyte capsules containing anti-inflammatory drug indomethacin were formed using layer-by-layer strategy, which involves alternative deposition of oppositely charged polyelectrolytes, such as poly(acrylic acid) and poly(ethyleneimine) (or chitosan) onto the drug substrate. Two variants of encapsulation have been implemented: direct deposition of polyelectrolytes onto indomethacin dispersed in water at рН 6, and preliminary formation of soft matrix by solubilization of indomethacin in micellar solutions of cationic surfactants. The inclusion of indomethacin into nanosized polyelectrolyte capsules (hydrodynamic diameter of three- and five-layer capsules is 90–180 nm) has given a new form of indomethacin with the drug content of 0.20–0.25%, which exceeds its limiting solubility in water nearly by the factor of 40. The choice of materials and procedures used for preparation of capsules, as well as the number of polyelectrolyte layers that form shell has provided the control of the drug release from capsule and resulted in the design of pharmaceutical dosage forms with long-lasting effect
Physicochemical properties and esterolytic reactivity of oxime functionalized surfactants in pH-responsive mixed micellar system
Effect of structure of polycyclic aromatic substrates on solubilization capacity and size of cationic monomeric and gemini 14-s-14 surfactant aggregates
Antimicrobial Properties and Cytotoxic Effect of Imidazolium Geminis with Tunable Hydrophobicity
Antimicrobial, membranotropic and cytotoxic properties of dicationic imidazolium surfactants of n-s-n (Im) series with variable length of alkyl group (n = 8, 10, 12, 14, 16) and spacer fragment (s = 2, 3, 4) were explored and compared with monocationic analogues. Their activity against a representative range of Gram-positive and Gram-negative bacteria, and also fungi, is characterized. The relationship between the biological activity and the structural features of these compounds is revealed, with the hydrophobicity emphasized as a key factor. Among dicationic surfactants, decyl derivatives showed highest antimicrobial effect, while for monocationic analogues, the maximum activity is observed in the case of tetradecyl tail. The leading compounds are 2–4 times higher in activity compared to reference antibiotics and prove effective against resistant strains. It has been shown that the antimicrobial effect is not associated with the destruction of the cell membrane, but is due to specific interactions of surfactants and cell components. Importantly, they show strong selectivity for microorganism cells while being of low harm to healthy human cells, with a SI ranging from 30 to 100
Enhanced Herbicidal Action of Clopyralid in the Form of a Supramolecular Complex with a Gemini Surfactant
Surfactants are often added to herbicidal formulations to improve the delivery of the herbicide into plants. In this study a new herbicidal formulation was formed based on the clopyralid with 0.01% gemini surfactant hexanediyl-1,6-bis(dimethylcetylammonium bromide) (16-6-16) as an adjuvant. The increase in the efficiency of the formulation was associated with the formation of a supramolecular surfactant–herbicide complex (SMC), which has improved wetting properties, provides high clopyralid concentration on the leaf surface, and has higher penetrating ability compared to surfactant-free clopyralid solutions. Comparison of the herbicidal action of clopyralid–16-6-16 SMC with two commercial formulations of the same concentration of clopyralid was performed using digital phenotyping of the model weed plant cocklebur (Xanthium strumarium). Based on the spectral indices NDVI (normalized differential vegetation index) and PSRI (plant senescence reflectance index) and key morphological indexes of the leaf angle, plant height, and leaf area, we showed that clopyralid formulations strongly affected the plants and that the strongest and most durable effect was exerted by the clopyralid–16-6-16 SMC formulation
Micellization and Catalytic Properties of Cationic Surfactants with Head Groups Functionalized with a Hydroxyalkyl Fragment
The catalytic activity of two homological series of cationic
surfactants
bearing a hydroxyalkyl fragment in the head groups RÂ(CH<sub>3</sub>)<sub>2</sub>N<sup>+</sup>(CH<sub>2</sub>CH<sub>2</sub>OH)ÂBr<sup>–</sup> and RÂ(CH<sub>3</sub>)<sub>2</sub>N<sup>+</sup>(CH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>OH)ÂBr<sup>–</sup> toward
the cleavage of the <i>p</i>-nitrophenyl esters of carbonic
acids of different hydrophobicity (acetate, caprilate, caprinate,
laurate, myristate) is shown to exceed that of typical cationic surfactants
with the trimethylammonium (TMA) headgroup. The catalytic effect increases
with the alkyl chain length of surfactants and nonmonotonous changes
in the series: acetate < caprilate < myristate < laurate
< caprinate, reaching 750 times. NMR and IR spectroscopy studies
and the surface potential calculations revealed that the higher catalytic
effect of hydroxyalkylated surfactants is not due to their higher
surface potential and binding capacity toward substrates. This is
in line with finding that binding constants for TMA series are higher
than for their hydroxyalkylated analogues, which was demonstrated
by the fitting of kinetic data
in terms of the pseudophase model. The microenvironment factor rather
than concentrating effect is responsible for the advanced catalytic
properties of hydroxyalkylated surfactants in the micellar phase
Novel cationic surfactants with cleavable carbamate fragment: Tunable morphological behavior, solubilization of hydrophobic drugs and cellular uptake study
Polyelectrolyte Capsules with Tunable Shell Behavior Fabricated by the Simple Layer-by-Layer Technique for the Control of the Release and Reactivity of Small Guests
A novel simple protocol for the layer-by-layer coating
of uncharged
organic substrates (hydrophobic carboxylic acid esters, CAEs) and
control of their loading/release behavior has been developed. The
approach involves the preliminary treatment of CAEs with the cationic
surfactant cetyltrimethylammonium bromide followed by polyÂ(acrylic
acid)/polyethyleneimine alternate deposition. The basic hydrolysis
of the substrates is used to spectrophotometrically control the loading/release
behavior through monitoring the absorbency of the reaction product <i>p</i>-nitrophenolate ion. Unlike the reactivity of free CAEs,
highly sensitive to the solution pH, and the presence of micellar
catalysts, the reaction rate of the loaded substrates is unaffected
by reaction conditions and can be administered by the capsule design
(numbers of deposition cycles, adjusted pH, ultrasonication). The
developed protocol makes it possible to omit the use of the sacrificial
template and stages of its removal. Capsules corresponding to the
biorelevant size criterion, with diameter of ≤200 nm, are obtained.
They can be successfully applied for sustaining the dosage of different
specimens with the desirable rate and for the control of the guest
reactivity by tuning the shell permeability