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1.
ACS Sens ; 9(1): 337-343, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38194413

RESUMO

Selective and sensitive detection of nitrite has important medical and biological implications. In the present work, to obtain an enhanced electrochemiluminescence (ECL) determination of nitrite, a novel nano-ECL emitter CoBIM/cetyltrimethylammonium bromide (CTAB) was prepared via a micelle-assisted, energy-saving, and ecofriendly method based on benzimidazole (BIM) and CTAB. Unlike conventional micelle assistance, the deprotonated BIM (BIM-) preferential placement was in the palisade layer of cationic CTAB-based micelles. Enriching the original CTAB micelle with BIM- disrupted its stability and resulted in the formation of considerably smaller BIM/CTAB-based micelles, providing a confined coordination environment for BIM- and Co2+. As a result, the growth of CoBIM/CTAB was also limited. Owing to the unusual nitration reaction between BIM and nitrite, the prepared CoBIM/CTAB was successfully applied as a novel ECL probe for the detection of nitrite with a wide linear range of 1-1500 µM and a low detection limit of 0.67 µM. This work also provides a promising ECL platform for ultrasensitive monitoring of nitrite and it was applied with sausages and pickled vegetables.


Assuntos
Compostos de Cetrimônio , Nitritos , Cetrimônio , Micelas , Benzimidazóis
2.
Spectrochim Acta A Mol Biomol Spectrosc ; 309: 123770, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38157746

RESUMO

In this study, the complexation of potential chemo-therapeutic antibacterial drug, ciprofloxacin (CIP) with varying concentrations of surface active compounds (SACs) i.e., (N-(2-hydroxyethyl)-N,N-dimethyl-1-dodecanaminium bromide (12Cho.Br) and cetyltrimethylammonium bromide (CTAB) has been studied. Multispectroscopic techniques were exploited to carry out the study. The higher binding constant (Kb) value for CIP-CTAB than CIP-12Cho.Br obtained from fluorescence data revealed stronger binding of CTAB than 12Cho.Br, owing to the stronger hydrophobic-hydrophobic interaction betweeen CIP and CTAB compared to CIP and 12Cho.Br. The time resolve fluorescence decay shows changes in average lifetime (τavg) with the increasing concentration of 12Cho.Br and CTAB. The changes in τavg suggests that complex formation is taking place between CIP and 12Cho.Br / CTAB. Further, the formation of micelles by 12Cho.Br / CTAB and the effect of alkyl chain length was studied by dynamic light scattering (DLS) and zeta potential to confirm the drug complexation with 12Cho.Br and CTAB. The antibacterial activity has been performed for CIP and 12Cho.Br and CTAB. It was observed that in presence of lower concentrations of 12Cho.Br/ CTAB, the activity of the drug increased. The activity was also found cationic alkyl chain length dependent. Moreover, in-vitro cytotoxicity of CIP and its combinations with 12Cho.Br and CTAB was performed using MTT assay on HEK293 (Human embryonic kidney cells).


Assuntos
Ciprofloxacina , Líquidos Iônicos , Humanos , Cetrimônio , Ciprofloxacina/farmacologia , Líquidos Iônicos/química , Tensoativos/química , Colina , Células HEK293 , Compostos de Cetrimônio/farmacologia , Compostos de Cetrimônio/química , Micelas , Antibacterianos/farmacologia
3.
Water Res ; 246: 120738, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37866246

RESUMO

Traditional research on biodegradation of emerging organic pollutants involves slow and labor-intensive experimentation. Currently, fast-developing metagenome, metatranscriptome, and metabolome technologies promise to expedite mechanistic research on biodegradation of emerging organic pollutants. Integrating the metagenome, metatranscriptome, and metabolome (i.e., tri-omics) makes it possible to link gene abundance and expression with the biotransformation of the contaminant and the formation of metabolites from this biotransformation. In this study, we used this tri-omics approach to study the biotransformation pathways for cetyltrimethylammonium bromide (CTAB) under aerobic conditions. The tri-omics analysis showed that CTAB undergoes three parallel first-step mono-/di-oxygenations (to the α, ß, and ω-carbons); intermediate metabolites and expressed enzymes were identified for all three pathways, and the ß-carbon mono-/di-oxygenation is a novel pathway; and the genes related to CTAB biodegradation were associated with Pseudomonas spp. Four metabolites - palmitic acid, trimethylamine N-oxide (TMAO), myristic acid, and betaine - were the key identified biodegradation intermediates of CTAB, and they were associated with first-step mono-/di-oxygenations at the α/ß-C. This tri-omics approach with CTAB demonstrates its power for identifying promising paths for future research on the biodegradation of complex organics by microbial communities.


Assuntos
Poluentes Ambientais , Metagenoma , Cetrimônio , Compostos de Cetrimônio , Metaboloma
4.
Indian J Med Microbiol ; 46: 100478, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37769586

RESUMO

BACKGROUND: Most studies on biocide resistance and its genetic determinants arise from environmental or food-borne microbial isolates and only a few from clinically relevant isolates. OBJECTIVES: This study determines the proportion of biocide resistance against five commonly used biocides and detects biocide resistance genes among MDR bacterial isolates using PCR. METHODS: Consecutive MDR isolates (n â€‹= â€‹180) were included (30 each of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus species) from clinical specimens of various inpatient units at JIPMER. The isolates were challenged at 0.5,1 and 2 Macfarland (McF) inoculum with discrete dilutions of disinfectants. The minimum bactericidal concentrations (MBCs) for 70% Ethanol, 1.5% Cresol, 2% Glutaraldehyde, 1% Cetrimide, and 1% Chlorhexidine were determined for the isolates using ATCC reference strains as controls. PCR was performed targeting qac A/B, G; smr; and nfx B genes. RESULTS: For all biocides, MDR isolates had MBCs less than the maximum MBCs of ATCC strains. For MDR K. pneumoniae, A. baumannii, and P. aeruginosa, the highest MBCs of chlorhexidine and cetrimide were ≥75 and â€‹≥ â€‹150 â€‹µg/ml respectively at 0.5 McF inoculum; whereas these organisms grew at higher inoculum (2McF) even at commercially recommended biocidal concentration (1%) corresponding to 750 and 1500 â€‹µg/ml of chlorhexidine and cetrimide respectively. Meanwhile, the highest MBCs of MDR E. coli were 75 and 150 â€‹µg/ml for chlorhexidine and cetrimide respectively. Interestingly, the Gram-positive cocci survived the action of up to 35% ethanol. The nfxB and qacG genes were detected in 87% and 6.67% of MDR P. aeruginosa isolates respectively with no biocide resistance genes detected among the other organisms. CONCLUSIONS: Biocide dilutions challenged with higher inoculum indicated a narrow margin of effectiveness for certain biocides. Although a significant proportion of clinical MDR isolates of P. aeruginosa harbored biocide resistance genes, this finding had no phenotypic correlation.


Assuntos
Desinfetantes , Humanos , Desinfetantes/farmacologia , Clorexidina , Escherichia coli , Centros de Atenção Terciária , Testes de Sensibilidade Microbiana , Etanol , Compostos de Cetrimônio , Antibacterianos/farmacologia
5.
Environ Sci Pollut Res Int ; 30(41): 94474-94484, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37535279

RESUMO

Cocoa shell was modified whit sodium hydroxide (NaOH) and cationic surfactant cetyltrimethylammonium bromide (CTAB) to increase surface functionality, surface area, and positive charge density. The prepared adsorbent CC-OH-CTAB was used to remove indigo carmine (IC) and bromocresol green (BCG) dyes from water. The optimal pH for IC and BCG adsorption were 2 and 4, respectively. The equilibrium was attained after a contact time of 30 min for IC and 120 min for BCG. The maximum adsorption capacity (Qmax) of IC and BCG obtained was 85.1 mg g-1 and 192.7 mg g-1, respectively. The Liu isotherm model best described the equilibrium results. The adsorption kinetics model showed that IC and BCG adsorption onto CC-OH-CTAB followed the pseudo-first-order and pseudo-second-order model, respectively. The regeneration and reusability experiments indicated that CC-OH-CTAB had much stability and excellent performance meanwhile repeatedly used. Finally, the insertion of CTAB on the CC-OH surface proved to be an excellent way to improve the adsorption performance of this material concerning dyes.


Assuntos
Corantes , Poluentes Químicos da Água , Cetrimônio , Corantes/química , Adsorção , Compostos de Cetrimônio/química , Índigo Carmim , Cinética , Poluentes Químicos da Água/análise , Concentração de Íons de Hidrogênio
6.
Aust Endod J ; 49(3): 530-536, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37464569

RESUMO

The objective of this research was to evaluate the efficacy of diclofenac sodium solutions, with or without cetrimide (CTR) added, against polymicrobial root canal biofilms grown in dentin specimens. The study groups were: (1) 5% diclofenac sodium (DCS); (2) 2.5% DCS; (3) 2.5% DCS + 0. 2% CTR; (4) 2.5% DCS + 0.4% CTR and (5) 0.9% saline solution (SS) as the control. After 5 min of solution contact with the biofilms, the antimicrobial activity was evaluated by means of the adenosine triphosphate (ATP) assay as well as confocal laser scanning microscopy (CLSM). Microbial quantification was indicated as the percentage reduction of relative light units (RLUs) for the ATP assay, the Log10 total biovolume and the viability percentage (green cells) for CLSM. Solutions of 2.5% DCS + 0.4% CTR and 5% DCS showed the highest antimicrobial efficacy. Cetrimide increased the antibiofilm activity of diclofenac sodium against endodontic biofilms.


Assuntos
Anti-Infecciosos , Diclofenaco , Diclofenaco/farmacologia , Cavidade Pulpar , Hipoclorito de Sódio/farmacologia , Irrigantes do Canal Radicular/farmacologia , Cetrimônio , Compostos de Cetrimônio , Biofilmes , Trifosfato de Adenosina , Enterococcus faecalis , Microscopia Confocal , Dentina
7.
Chemistry ; 29(27): e202203764, 2023 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-36808662

RESUMO

The emergence of catalytic activity associated with a disassembly process is reported, reminiscent of complex biological systems. A cystine derivative with pendant imidazole groups self-assembles into cationic nanorods in the presence of the cationic surfactants cetylpyridinium chloride (CPC) or cetyltrimethylammonium bromide (CTAB). Disulfide reduction triggers nanorod disassembly and the generation of a simple cysteine protease mimic, which shows a dramatically improved catalytic efficiency in the hydrolysis of p-nitrophenyl acetate (PNPA).


Assuntos
Cisteína Proteases , Nanotubos , Cetrimônio , Tensoativos , Compostos de Cetrimônio , Cátions
8.
Soft Matter ; 19(7): 1429-1439, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36723251

RESUMO

Catanionic surfactant vesicles (SVs) composed of sodium dodecylbenzenesulfonate (SDBS) and cetyltrimethylammonium tosylate (CTAT) have potential applications as targeted drug delivery systems, vaccine platforms, and diagnostic tools. To facilitate these applications, we evaluated various methods to attach proteins to the surface of SDBS/CTAT vesicles. Acid phosphatase from wheat germ was used as a model protein. Acid phosphatase was successfully conjugated to vesicles enriched with a Triton-X 100 derivative containing an unsaturated ester. Enzymatic activity of acid phosphatase attached to vesicles was assessed using an acid phosphatase assay. Results from the acid phosphatase assay indicated that 15 ± 3% of the attached protein remained functional but the presence of vesicles interferes with the assay. DLS and zeta potential results correlated with the protein functionalization studies. Acid phosphatase functionalized vesicles had an average diameter of 175 ± 85 nm and an average zeta potential of -61 ± 5 mV in PBS. As a control, vesicles enriched with Triton-X 100 were prepared and analyzed by DLS and zeta potential measurements. Triton X-100 enriched vesicles had an average diameter of 140 ± 67 nm and an average zeta potential of -49 ± 2 mV in PBS. Functionalizing the surface of SVs with proteins may be a key step in developing vesicle-based technologies. For drug delivery, antibodies could be used as targeting molecules; for vaccine formulation, functionalizing the surface with spike proteins may produce novel vaccine platforms.


Assuntos
Compostos de Cetrimônio , Tensoativos , Sistemas de Liberação de Medicamentos , Fosfatase Ácida
9.
Dalton Trans ; 52(4): 1052-1061, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36602082

RESUMO

The spectrum and size controllable synthesis of gold nanorods is of great value for their widely applicable aspect ratio dependence of anisotropic surface plasmon resonance. Herein, 1,7-dihydroxynaphthalene with a relatively strong reducibility is proposed as a reducing agent for the controllable synthesis of gold nanorods. The result indicated that gold nanorods with high monodispersity, high shape yield, relatively small diameters, and maximum plasmon resonance wavelength of above 1000 nm can be acquired. More importantly, by virtue of the reducing agent used, fine and precise controls over the plasmon wavelength and diameter of the rod can be achieved via changes in experimental conditions. In particular, increases in the concentration of both silver ions and cetyltrimethylammonium bromide (CTAB) can increase the plasmon wavelength from around 600 nm to 1000 nm but respectively show a decreased diameter with the smallest value of around 14.3 nm and a mildly increased diameter from around 9.0 nm to 14.3 nm; moreover, increasing the concentration of reducing agents and gold seeds can simultaneously cause decreases in the plasmon wavelength from around 1000 nm to 800 nm and the diameters from around 14.3 nm to 9.0 and 7.3 nm, respectively. This powerful and efficient method of controllable synthesis of AuNRs could be valuable and attractive for the application of the as-obtained particles.


Assuntos
Nanotubos , Substâncias Redutoras , Ouro , Cetrimônio , Compostos de Cetrimônio
10.
J Colloid Interface Sci ; 631(Pt A): 202-211, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36375300

RESUMO

HYPOTHESIS: Quatsome nanovesicles, formed through the self-assembly of cholesterol (CHOL) and cetyltrimethylammonium bromide (CTAB) in water, have shown long-term stability in terms of size and morphology, while at the same time exhibiting high CHOL-CTAB intermolecular binding energies. We hypothesize that CHOL/CTAB quatsomes are indeed thermodynamically stable nanovesicles, and investigate the mechanism underlying their formation. EXPERIMENTS: A systematic study was performed to determine whether CHOL/CTAB quatsomes satisfy the experimental requisites of thermodynamically stable vesicles. Coarse-grain molecular dynamics simulations were used to investigate the molecular organization in the vesicle membrane, and the characteristics of the simulated vesicle were corroborated with experimental data obtained by cryo-electron microscopy, small- and wide-angle X-ray scattering, and multi-angle static light scattering. FINDINGS: CHOL/CTAB quatsomes fulfill the requisites of thermodynamically stable nanovesicles, but they do not exhibit the classical membrane curvature induced by a composition asymmetry between the bilayer leaflets, like catanionic nanovesicles. Instead, CHOL/CTAB quatsomes are formed through the association of intrinsically planar bilayers in a faceted vesicle with defects, indicating that distortions in the organization and orientation of molecules can play a major role in the formation of thermodynamically stable nanovesicles.


Assuntos
Compostos de Cetrimônio , Simulação de Dinâmica Molecular , Cetrimônio , Microscopia Crioeletrônica , Compostos de Cetrimônio/química , Colesterol/química , Bicamadas Lipídicas/química
11.
Langmuir ; 38(48): 14768-14778, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36437713

RESUMO

A catanionic surfactant system is an aqueous solution or dispersion of cationic and anionic surfactants that spontaneously self-assemble into structures such as micelles, vesicles, and coacervates. Their structural diversity varies depending on the ratios of cationic and anionic surfactants (compositions), the chemical structure of the constituent molecules, etc. Herein, two types of catanionic surfactant systems were systematically characterized: (i) cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), both typical ionic surfactants; and (ii) dodecylmethylimidazolium ammonium bromide ([C12mim]Br) and SDS, where the former is an ionic liquid. By observing the sample appearance, turbidity, and particle size, the phase state of each system was analyzed according to the total concentration of surfactants and the molar ratio of cationic surfactants to the total concentration. Especially, for specific compositions of catanionic surfactant vesicles (cataniosome), the closed structure of the vesicles was confirmed through calcein entrapment and release detected with a fluorescence assay. The polarities of the interface of the prepared self-assemblies were evaluated using a fluorescence probe, Laurdan. The packing state of the molecules in the formed self-assembly structure was estimated using Raman spectroscopy. The results clearly indicate consistent phase-transition behavior for the CTAB-SDS (i) and [C12mim]Br-SDS (ii) systems, depending on the total surfactant concentration and composition, while the membrane properties of the two systems differed. The cataniosome formed in the CTAB-SDS system was in a tightly packed membrane state and more hydrophobic than that formed in the [C12mim]Br-SDS system owing to the difference in the structure of the constituting molecule: [C12mim]Br has a larger head group and shorter acyl chain than CTAB. The self-assembly properties evaluated in this study were compared with those of typical lipid membranes, liposomes (lipid vesicles), to determine a possible application of the catanionic systems with various self-assembly formulations.


Assuntos
Surfactantes Pulmonares , Tensoativos , Tensoativos/química , Cetrimônio , Dodecilsulfato de Sódio/química , Compostos de Cetrimônio/química , Cátions/química , Excipientes
12.
Molecules ; 27(14)2022 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-35889205

RESUMO

In recent years, there has been increasing interest in daily-use chemical products providing a pleasant scent. The added fragrance molecules may induce microstructural transitions of surfactant aggregates, which further affect the physical and chemical properties of the products. Here, the effects of four types of aromatic alcohols (cinnamyl alcohol, phenyl ethanol, phenyl methanol and anisyl alcohol) on cetyltrimethylammonium bromide (CTAB)/KBr aggregates were studied. The combined results from rheology, dynamic light scattering, and transmission electron microscopy measurements showed that cinnamyl alcohol induced significant micellar growth, while increases in micellar growth were less obvious for the other aromatic alcohols. The changes in the interfacial molarities of water, aromatic alcohol, and bromide ions during such transitions were studied using the chemical trapping method. Transitions resulting from added cinnamyl alcohol were accompanied by significant declines in interfacial water and bromide ion molarities, and a rise in interfacial alcohol molarity. The marked decrease in interfacial water molarity was not observed in previous studies of the octanol induced formation of wormlike micelles and vesicles, indicating that a different mechanism was presented in the current system. Nuclear magnetic resonance investigation showed that π-π stacking between cinnamyl alcohols, but not cation-π interactions between alcohols and CTAB headgroups, facilitated the tight packing of alcohol molecules in CTAB aggregates and the repulsion of water from the interfacial region. The current study may provide a theoretical basis for the morphological regulation of surfactant aggregates in the presence of additives.


Assuntos
Surfactantes Pulmonares , Tensoativos , Brometos , Cetrimônio , Compostos de Cetrimônio/química , Excipientes , Micelas , Odorantes , Tensoativos/química , Água/química
13.
Appl Opt ; 61(10): 2864-2868, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35471371

RESUMO

The major goal of this study was to find predictors of plasmon positions in silver nanorod (NR) optical absorption spectra. The goal of this study is to use an adaptive neural fuzzy inference system to identify the various input parameters for longitudinal surface plasmon resonance (LSPR) and transverse surface plasmon resonance (TSP). A seed strategy has been used for preparation of the silver NRs. During the preparation, the seed particles are synthesized in the presence of cetyltrimethylammonium bromide (CTAB). To produce the silver NRs, metal salt (AgNO3) has been added, as well as ascorbic acid (AA) and CTAB. Skillful prediction could play a pivotal role in the plasmon NR production management. The combination of CTAB and the seeds has the largest influence on the TSPR. The combination of CTAB and AA has the largest influence on the LSPR. The study considering different input parameters simultaneously, to the best of our knowledge, is the first on a small scale and should attract great general interest.


Assuntos
Nanotubos , Prata , Cetrimônio , Compostos de Cetrimônio , Ouro
14.
Langmuir ; 38(8): 2486-2494, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-35164504

RESUMO

Although worm-like micelles were invented 35 years ago, its formation pathway remains unclear. Inspired by the fact that a single molecular level experiment could provide meaningful and additional information, especially in a heterogeneous subpopulation, herein, we present a single molecular level study on the formation of wormlike micelles by cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) in water. Our results indicated a coexistence of normal spherical micelles along with a big wormlike micelle in its formation path. More interestingly, we have two unique insights into the formation mechanism, which are inaccessible in ensemble averaged experiments: (i) at extremely low concentrations of the surfactant, [CTAB]/[NaSal] ∼ 0.06, the wormlike micelle attains the highest size; and (ii) the relative concentration of wormlike micelles is highest when [CTAB]/[NaSal] ∼ 2.


Assuntos
Compostos de Cetrimônio , Micelas , Cetrimônio , Compostos de Cetrimônio/química , Espectrometria de Fluorescência , Tensoativos/química
15.
J Colloid Interface Sci ; 610: 785-795, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34876264

RESUMO

HYPOTHESIS: Molecular interactions between 4-OH-cinnamate and cetrimonium in solution result in improved adsorption of the cinnamate on mild steel, developing a protective mechanism against the diffusion of corrosive chloride to the oxide surface. Fundamental understanding of this mechanism should allow new design routes for the development of eco-friendly corrosion inhibitors. EXPERIMENTS: Via classic molecular dynamics, simulations were carried out for cetrimonium and 4-OH-cinnamate in aqueous solutions at different ionic strengths and the results were validated with experimental SAXS data. Self-aggregation of cetrimonium 4-OH-cinnamate on a hydrated hematite surface was then simulated and results were compared with cryo-TEM imaging for the same compound. Finally, the effect of the adsorbed aggregates on chloride diffusion to the oxide surface was modelled. FINDINGS: Simulations showed the encapsulation of 4-OH-cinnamate into cetrimonium micelles, consistent with experiments. The newly formed micelles adsorb onto a hydrated iron oxide surface by forming hydrogen bonds between their carboxylate outer-shell groups and the surface hydroxyls. As the adsorbate concentrations increase, there is a morphological transition from spherical to wormlike adsorbed aggregates. The wormlike structure can block chloride ions, demonstrating a synergistic inhibitory mechanism between both cetrimonium and 4-OH-cinnamate. Encapsulation and delivery of active compounds to certain targets, such as carcinogenic tumors, have been well studied in biochemistry research, we demonstrate that the same mechanism can be applied to the design of efficient corrosion inhibitors, optimizing their delivery to the metal surface.


Assuntos
Cinamatos , Micelas , Cetrimônio , Compostos de Cetrimônio , Compostos Férricos , Espalhamento a Baixo Ângulo , Tensoativos , Difração de Raios X
16.
J Chromatogr A ; 1660: 462654, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34788671

RESUMO

A stacking technique is proposed to improve the poor detection sensitivity of capillary zone electrophoresis (CZE) with UV detection. A long injection (e.g., 12.4 cm plug) of model anionic analytes prepared in a dilute solution of hexadecyltrimethylammonium bromide (CTAB) was enriched 26-34-x (compared to a typical or 2.1 mm sample injection) via the injection of a micellar solution of sodium dodecyl sulfate (SDS) prior to CZE separation. During sample injection, the CTAB formed a stationary pseudophase coating, which trapped the analytes at the inner walls of a fused silica capillary. The SDS micelles then released the CTAB admicelles via the formation of solution CTAB-SDS catanionic micelles during SDS plug injection and voltage application. As the SDS micelles moved through the sample zone, the formation of the catanionic micelles then released and accumulated the analytes at the front of the injected SDS zone. The stacking technique is called electroosmotic flow (EOF) assisted pseudophase to pseudophase microextraction because the EOF was essential for the formation of CTAB-SDS catanionic micelles for microextraction. Also, the CTAB and SDS aggregates are both pseudophases, which were used to retain and release the analytes from the capillary wall, respectively.


Assuntos
Eletro-Osmose , Eletroforese Capilar , Cetrimônio , Compostos de Cetrimônio , Micelas , Dodecilsulfato de Sódio
17.
J Colloid Interface Sci ; 604: 757-766, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34293533

RESUMO

HYPOTHESIS: The previously observed effects of nonpolar additives on the scission energy and rheological properties of surfactant wormlike micelles can be explained in terms of the spatial distribution of the additive within the micelles. The dependence of the scission energy with the molecular organization of the system can be analyzed with a molecular theory capable of describing the thermodynamics and structure of the micelles. THEORY: A new theoretical method to determine the scission energy of surfactant wormlike micelles is introduced. This methodology is based on a molecular theory that explicitly considers molecular details of all components of the micelles, and their inter- and intramolecular interactions without the use of fitting and/or empirical macroscopic parameters. FINDINGS: The predicted effects of the concentration, molecular structure and hydrophobicity of the additive on the scission energy of cetyltrimethylammonium bromide (CTAB) wormlike micelles are found to be in qualitative agreement with previous experimental observations. In particular, our theory captures the decrease of micellar length with increasing content of highly hydrophobic additives and the non-monotonic dependence of the viscosity with additive hydrophobicity. The latter effect arises because highly and mildly hydrophobic additives affect the scission energy of wormlike micelles via markedly different molecular mechanisms.


Assuntos
Micelas , Surfactantes Pulmonares , Cetrimônio , Compostos de Cetrimônio , Tensoativos
18.
Langmuir ; 37(25): 7681-7688, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34139839

RESUMO

The influence of mercury on the morphology and formation mechanism of gold amalgams in the presence of different reducing agents (ascorbic acid and sodium borohydride) was systematically studied. In the presence of cetyltrimethylammonium bromide (CTAB), chemical reducing agents not only reduced mercury ions in the solution but also replaced the CTAB molecules on the surface of the gold nanorod. The stability of the reducing agents in the colloidal system and the combining capacity of the reducing agent to the gold nanoparticles can affect the alloying process of mercury and gold, thereby forming a rod-shaped or spherical gold amalgam. Once CTAB was removed, a similar transformation process occurs between the gold nanorods and mercury. In addition, without the presence of a stabilizer, mercury that cannot be dispersed undergoes Ostwald ripening growth, which causes the gold amalgam nanoalloys to form a tip-to-tip structure as a result of mercury enrichment because of the weak shielding effects occurring at the tips of the gold nanorods. After the CTAB molecules were substituted with ascorbic acid and alkylthiol molecules, the question of whether the shielding effect weakened or disappeared was also investigated. By investigation, this research found that, in comparison to the blocking effect of CTAB molecules, the binding ability of the reducing agent to gold plays a dominant role in the nanoamalgam formation process.


Assuntos
Nanopartículas Metálicas , Nanotubos , Compostos de Cetrimônio , Ouro , Substâncias Redutoras
19.
Langmuir ; 37(15): 4611-4621, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33843215

RESUMO

In this work, we characterize the micellization and morphology transition induced in aqueous cetyltrimethylammonium bromide (CTAB) solution by the addition of the antioxidant propyl gallate (PG) using tensiometry, rheology, and small-angle neutron scattering (SANS) techniques combined with the molecular dynamics (MD) simulation approach. The adsorption of CTAB at the air-water interface in the presence of varying [PG] revealed a progressive decrease in the critical micelle concentration (CMC), while the changes in different interfacial parameters indicated enhancement of the hydrophobicity induced by PG in the CTAB micellar system. The dynamic rheology behavior indicated an increase in the flow viscosity (η) as a function of [PG]. Moreover, the rheological components (storage modulus, G', and loss modulus, G″) depicted the viscoelastic features. SANS measurements depicted the existence of ellipsoidal micelles with varying sizes and aggregation number (Nagg) as a function of [PG] and temperature. Computational simulation performed using density functional theory (DFT) calculations and molecular dynamics (MD) provided an insight into the atomic composition of the examined system. The molecular electrostatic potential (MEP) analysis depicted a close proximity of CTAB, i.e., emphasized favorable interactions between the quaternary nitrogen of CTAB and the hydroxyl group of the PG monomer, further validated by the two-dimensional nuclear Overhauser enhancement spectroscopy (2D-NOESY), which showed the penetration of PG inside the CTAB micelles. In addition, various dynamic properties, viz., the radial distribution function (RDF), the radius of gyration (Rg), and solvent-accessible surface area (SASA), showed a significant microstructural evolution of the ellipsoidal micelles in the examined CTAB-PG system, where the changes in the micellar morphology with a more elongated hydrophobic chain and the increased Rg and SASA values indicated the notable intercalation of PG in the CTAB micelles.


Assuntos
Compostos de Cetrimônio , Micelas , Antioxidantes , Cátions , Cetrimônio , Tensoativos
20.
Int J Infect Dis ; 105: 702-708, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33636356

RESUMO

OBJECTIVE: Catheter-associated urinary tract infection (CAUTI) is a common nosocomial infection. However, there has been no randomized control trial (RCT) comparing the efficacy of periurethral cleaning solutions for reducing CAUTI. This study aimed to compare the efficacy of normal saline solution (NSS) and Savlon solution. METHODS: A non-inferiority cross-over RCT was conducted to compare the 2 solutions by the incidence of significant bacteriuria (SB) on day 5 after Foley catheterization. Patients admitted to a tertiary referral hospital from June 2018 to August 2019 participated in the study. The acceptable prespecified non-inferiority margin was 10%. RESULTS: There were 265 and 275 patients in the NSS and Savlon groups, respectively. The incidence of CAUTI was 2.65/1000 catheter-days, and the median duration of catheterization was 5 days (IQR 4, 7). There was no significant difference between the incidence of SB in the NSS and Savlon groups, as indicated by the adjusted difference of 0.6 (95% CI: -3.1-4.2). CONCLUSION: This study was the first RCT in patients from multiple hospital units to compare the efficacy of the 2 solutions in the periurethral cleaning process. The study demonstrated non-inferiority of NSS to Savlon solution. THAI CLINICAL TRIALS REGISTRY STUDY ID: TCTR20180518001.


Assuntos
Anti-Infecciosos/uso terapêutico , Bacteriúria/prevenção & controle , Infecções Relacionadas a Cateter/prevenção & controle , Compostos de Cetrimônio/uso terapêutico , Clorexidina/uso terapêutico , Solução Salina/uso terapêutico , Infecções Urinárias/prevenção & controle , Adulto , Idoso , Idoso de 80 Anos ou mais , Bacteriúria/epidemiologia , Infecções Relacionadas a Cateter/microbiologia , Cateteres de Demora/efeitos adversos , Cateteres de Demora/microbiologia , Infecção Hospitalar/microbiologia , Infecção Hospitalar/prevenção & controle , Combinação de Medicamentos , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Cateterismo Urinário/efeitos adversos , Infecções Urinárias/microbiologia , Adulto Jovem
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