Effect of the Structural and Morphological Properties of Surfactant-Assisted Hydroxyapatite on Dermal Irritation and Antibacterial Activity

Hydroxyapatite (HAp) nanoparticles with a homogeneous rod morphology were successfully synthesized using the hydrothermal method. The powders were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The antibacterial and dermal irritation analyses of the samples were performed and discussed. The use of cationic and anionic surfactants, namely, cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), respectively, at a low concentration (2.5 mol%) modified the length/diameter (L/D) ratio of the HAp rods. Structural characterizations of hydroxyapatite synthesized without surfactant (HA), with 2.5 and 5 mol% of SDS (SDS− and SDS+, respectively), and with 2.5 and 5 mol% of CTAB (CTAB− and CTAB+, respectively) revealed well-crystallized samples in the hexagonal phase. The CTAB− sample presented antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Streptococcus anginosus, Staphylococcus aureus, Micrococcus luteus, and Klebsiella pneumoniae, suggesting that antimicrobial susceptibility was promoted by the bacterial nature and the use of the surfactant. Dermal irritation showed no clinical signs of disease in rabbits during the study, where there was neither erythema nor necrosis at the inoculation sites.

Terbium(III) as a Fluorescent Probe for Molecular Detection of Ascorbic Acid

Fluorescence analysis is a simple and a highly sensitive method for detection of small amounts of biologically active substances. In this study, a complexation of terbium(III) chelates with 1,10-phenanthroline and ascorbic acid (AA) and luminescent properties of complexes were investigated. The influence of pH and solubilization of complexes by micellar solutions of nonionic, cationic, and anionic surfactants on fluorescence was studied. The quenching effect of terbium ion fluorescence was detected upon an introduction of ascorbic acid. The quenching effect of the complex with mixed ligands Tb(1,10-phenanthroline)-AA allows for the detection of ascorbic acid with the limit of 7.4 × 10−5 mol·L−1.

Features of the discharge of zinc in the background solution of sodium sulphate under stirring conditions

The production technology of hydrometallurgical zinc uses various surfactants to thicken pulps, stabilise the electrolysis process, and obtain high-quality cathode deposits. Numerous researches were conducted to study the cathodic and anodic processes in a wide range of the composition of aqueous solutions using various solid electrodes in the absence of intense stirring of the electrolyte and with a high contribution of the migration component of the discharge of metals. This approach to the study of the surfactants’ influence rarely provided a high degree of statistical reliability in observing the effect of differently charged surfactants on electrode processes, which is of great importance in the hydrometallurgical production of zinc. In this work, the task was to practically eliminate the contribution of the migration component due to the followingfactors: conducting electrolysis in a background solution of sodium sulphate, organising electrolyte stirring, performing calculations of current densities at the beginning of electrolysis, and establishing polarisation curves at an increased potential sweep rate from 20 to 100 mV/s. This approach provided a greater degree of statistical reliability in presenting the mechanism of the effect of additions of cationic and anionic surfactants during the stage of zinc discharge on a solid electrode, which was the purpose of the article.Electrolysis was conducted in the potential range from -1050 to -1250 mV relative to the silver chloride electrode (AgCl/Ag) in the presence of a background sodium sulphate solution (0.5 M of Na2SO4 solution) containing 0.005, 0.0125, and 0.025 M ZnSO4 with the introduction of high-molecular surfactants: cationic and anionic coagulants (flocculants) and foaming agents (lignosulphonate – LSTP).During the electrolysis in a background solution of sodium sulphate with stirring, it was found that the process of discharge of zinc ions on a solid electrode occurs in a mixed-kinetic mode. It was shown that positively charged additives, such as lignosulphonate and cationic coagulant (flocculant) Besfloc K6645, have a negative effect on the dynamics of zinc cation discharge, while negatively charged Besfloc K4034 has practically no effect. The approach proposed in this work allows evaluating the influence of additions of cationic and anionic surfactants on the stage of zinc discharge on a solid electrode, which was the practical and scientific value of this work

Interaction of Diphenhydramine Hydrochloride with Cationic and Anionic Surfactants: Mixed Micellization and Binding Studies

The focus of the present work is to evaluate the interactions of an anti-allergic drug (diphenhydramine hydrochloride, DPH) with anionic (sodium dodecyl sulfate, SDS) and cationic (cetylpyridinium chloride, CPC) surfactants in the aqueous medium. The mixed micellization behavior and surface properties of drug-surfactant mixtures have been examined by surface tension measurements. Various theoretical approaches were applied to explore the synergistic or non-ideal behavior of the current mixed systems. Furthermore, the binding studies of drug with surfactants have been elaborated by UV–visible spectroscopy. Benesi–Hildebrand (B-H) theory was used to compute stoichiometric ratio, binding constant, and free energy change for the drug-surfactant mixtures. The outputs are deliberated taking into consideration the use of surfactants as capable drug delivery agents for DPH and hence advance bioavailability.

Test methods for determining cationic and anionic surfactants in disinfecting and technological solutions

The purpose of the work was to develop Express methods for determining cationic and anionic surfactants in disinfectants and process solutions. The surfactant concentration was determined visually and colorimetrically by the intensity of color of the indicator zones of paper test strips or by the length of the colored (discolored) zones of test strips laminated in a polymer film. Semi-quantitative determination of surfactants in solutions was carried out by the intensity of color of the zones of indicator test strips pasted on the substrate (test titration on paper). Bromphenol blue was used as an indicator. The titrant was sodium dodecyl sulfate for cationic surfactants and cetylpyridinium chloride for anionic surfactants. Test strips were used for the determination of surfactants in the disinfectant solutions. The concentration in the range of 0.1 – 1.2% was determined by comparing the color with the standard color scale. The duration of the analysis was 3 – 5 min. Quantitative determination of surfactants was carried out by the length of the colored (discolored) zones of test strips glued in a polymer film. As an indicator for cationic surfactants, bromphenol blue (blue zone on the test strip) was used, and for anionic surfactants, an associate of bromphenol blue with cetylpyridinium chloride (discolored zone on the test strip). The determination range of the surfactant made up 16 – 1000 mg/liter. The concentration was determined according to a calibration graph representing the dependence of the length of the blue/discolored zone of the test strips on the concentration of surfactants in the solution. The relative standard deviation of the analysis results does not exceed 0.3; the analysis duration was 20 – 30 min.

Ir-Ni based mono and bimetallic nanocrystals: synthesis, characterization and effect of cationic, anionic, and non-ionic stabilizers

Nickel based bimetallic nanocrystals, iridium-nickel play an imperative role in catalysis, electrocatalysis, and magnetic applications. In the present work Ir-Ni bimetallic nanoalloys were synthesized by modified polyol reduction method with different cationic, anionic, and non-ionic surface active agents like CTAB, SDS, TSC, and PVP. The non-ionic surface active agent PVP produced a better effect on nanoparticle size than cationic and anionic surfactants. The synthesized bimetallic nanocrystals were characterized by UV-Vis, XRD, FTIR, FESEM, and HRTEM techniques. XRD and FTIR verify the nature of synthesized bimetallic nanocrystals and the interaction between stabilizers and nanoparticles. HRTEM studies reveal that the PVP stabilized Ir-Ni (3:1) and Ir-Ni (1:1) bimetallic nanocrystals are small in size and less dispersed. Particle size range of these nanoparticles is from (1.77-2.36) nm. FESEM images show that nanoparticles are in quasi spherical shape. EDX analysis indicates that the resultant particles are core shell structure with Ni core and Ir shell.

Simultaneous Determination of Iron and Cobalt using Spectrophotometry after Catanionic Mixed Micellar Cloud Point Extraction Procedure

A new preconcentration method which utilises a mixture of cationic and anionic surfactants for separation and spectrophotometric determination of iron and cobalt simultaneously has been developed. The metal ions, iron and cobalt were complexed with thiocyante. The hydrophobic complexes of iron and cobalt were then extracted into catanionic mixed micelles of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). Different parameters like concentration of HCl, concentration of thiocyanate, concentrations of the surfactants (CTAB and SDS), equilibration temperature and time were studied to get maximum efficiency. The linear ranges of Fe3+ and Co2+ were found to be 0.139 – 0.838 μg mL–1 and 5.89 – 35.4 μg mL–1, respectively the detection limits obtained were 1.54 ng mL–1 and 6.18 ng mL–1. The developed procedure has been employed for the retrieval of Fe3+ and Co2+ in water samples successfully (tap water and sea water). 98 – 107% recoveries were obtained.