Employing Sodium Dodecyl Sulfate Research Articles

Analytical Quality by Design-Compliant Development of a Cyclodextrin-Modified Micellar ElectroKinetic Chromatography Method for the Determination of Trimecaine and Its Impurities.

In 2022, the International Council for Harmonisation released draft guidelines Q2(R2) and Q14, intending to specify the development and validation activities that should be carried out during the lifespan of an analytical technique addressed to assess the quality of medicinal products. In the present study, these recommendations were implemented in Capillary Electrophoresis method development for the quality control of a drug product containing trimecaine, by applying Analytical Quality by Design. According to the Analytical Target Profile, the procedure should be able to simultaneously quantify trimecaine and its four impurities, with specified analytical performances. The selected operative mode was Micellar ElectroKinetic Chromatography employing sodium dodecyl sulfate micelles supplemented with dimethyl-β-cyclodextrin, in a phosphate-borate buffer. The Knowledge Space was investigated through a screening matrix encompassing the composition of the background electrolyte and the instrumental settings. The Critical Method Attributes were identified as analysis time, efficiency, and critical resolution values. Response Surface Methodology and Monte Carlo Simulations allowed the definition of the Method Operable Design Region: 21-26 mM phosphate-borate buffer pH 9.50-9.77; 65.0 mM sodium dodecyl sulfate; 0.25-1.29% v/v n-butanol; 21-26 mM dimethyl-β-cyclodextrin; temperature, 22 °C; voltage, 23-29 kV. The method was validated and applied to ampoules drug products.

Enhancing oral bioavailability of andrographolide via sodium dodecyl sulfate and D-α-Tocopherol polyethylene glycol 1000 succinate copolymer modified nanocrystals

Nanocrystal technology is a common strategy to enhance the oral bioavailability of poorly-soluble drugs, and how to enlarge the enhancing ability on oral absorption via nanocrystals has become a pharmaceutical research field. In this study, we selected andrographolide (ADR), a typical poorly-soluble drug, as the model drug, and employed sodium dodecyl sulfate and D-ɑ-Tocopherol polyethylene glycol 1000 succinate copolymer (SDS-TPGS) to construct novel SDS-TPGS modified andrographolide nanocrystals (S-TANs). We found that the particle sizes of SDS/TPGS physical mixture modified nanocrystals (STANs) were about 553.4 ± 4.1 nm, while that of SDS-TPGS modified nanocrystals (S-TANs) were 604.6 ± 5.7 nm. During the production process of nanocrystals, the crystallinity of ADR was slightly decreased. Nanocrystals enhanced the saturation solubility of ADR, and improved oral absorption, Cmax and AUC0-∞ of S-TANs was about 2.10 and 1.24 fold increased, STAN about 2.63, 2.97 fold. In a Real-time distribution study, we found the distribution time of andrographolide, SDS and TPGS in SDS/TPGS physical mixture modified nanocrystals system varies widely, while the distribution times of these materials were similar in SDS-TPGS copolymer modified nanocrystals system. These results indicated that modified with functional stabilizer was an efficient strategy to enlarge the enhancing ability on oral absorption of nanocrystals, and synthesized copolymer containing different functional stabilizers showed higher ability on enhancing oral bioavailability than physical mixtures.

Improving Oral Bioavailability of Luteolin Nanocrystals by Surface Modification of Sodium Dodecyl Sulfate.

Luteolin suffers from drawbacks like low solubility and bioavailability, thus hindering its application in the clinic. In this study, we employed sodium dodecyl sulfate (SDS), an efficient tight junction opening agent, to modify the surface of luteolin nanocrystals, aiming to enhance the bioavailability of luteolin (LUT) and luteolin nanocrystals (LNC). The particle sizes of SDS-modified luteolin nanocrystals (SLNC) were slightly larger than that of LNC, and the zeta potential of LNC and SLNC was -25.0 ± 0.7 mV and -43.5 ± 0.4 mV, respectively. Both LNC and SLNC exhibited enhanced saturation solubility and high stability in the liquid state. In the cellular study, we found that SDS has cytotoxicity on caco-2 cells and could open the tight junction of the caco-2 monolayer, which could lead to an enhanced transport of luteolin across the intestinal membrane. The bioavailability of luteolin was enhanced for 1.90-fold by luteolin nanocrystals, and after modification with SDS, the bioavailability was enhanced to 3.48-fold. Our experiments demonstrated that SDS could efficiently open the tight junction and enhance the bioavailability of luteolin thereafter, revealing the construction of SDS-modified nanocrystals is a good strategy for enhancing the oral bioavailability of poorly soluble drugs like luteolin.

Degradation of common polymers in sewage sludge purification process developed for microplastic analysis.

To enable and/or facilitate analysis of microplastics from environmental samples, a purification process is required to reduce the organic matter content. The development of such process has as one main concern, besides achieving efficient organic matter reduction, the preservation of the microplastics. In this study, a three-step method for sewage sludge purification was proposed employing sodium dodecyl sulfate and hydrogen peroxide. The effects of the purification method on seven polymers (LLDPE, HDPE, PP, PS, PET, PA66 and SBR) were evaluated in terms of mass change, surface characteristics, mechanical properties, thermal properties and functional groups change. It was also assessed how the polymers were affected by the purification chemicals without the presence of sewage sludge. The purification process led to changes in all tested plastics, but in different intensities. LLDPE, HDPE, PP, PS and PET did not suffer considerable degradation. PET was more affected by hydrolysis than oxidation. On the other hand, the integrities of PA66 and SBR were noticeably affected. The effects of the purification process were considered to be due to the plasticizer behavior of water and oxidation on PA66 and loss of filler and oxidation on SBR. For both polymers there was a reduction on the tensile strength of around 50-60% after the purification, indicating they could be prone to fragmentate into smaller pieces along the process. After purification, PA66 also started to decompose at a temperature around 10°C lower comparing to virgin samples. Except for SBR, the presence of sewage sludge and its oxidation was more harmful to the polymers than the purification chemicals without the presence of sewage sludge. This study serves as an evaluation of the effects of the purification process on the degradation of microplastics and a methodology for such assessment when designing a purification process.

Adsorption behavior and mechanism of acid orange 7 and methylene blue on self-assembled three-dimensional MgAl layered double hydroxide: Experimental and DFT investigation

The removal of toxic ionic dyes is an urgent issue in the water pollution control field. Herein, the self-assembled three-dimensional MgAl layered double hydroxide (3D-MA-LDH) have been synthesized via the soft-template synthesis employing sodium dodecyl sulfate (SDS) as soft template and can be successfully applied in the anionic azo dye Acid Orange 7 (AO7) and cationic heteroaromatic compound methylene blue (MB) removal. The maximum removal capacities were 485.6 and 58.3 mg·g−1 for AO7 and MB, respectively. The removal behavior for AO7 and MB fitted the Langmuir and Freundlich model, respectively, and revealed a diffusion process contained chemical adsorption. X-ray diffraction, Fourier transform spectroscopy, and X-ray photoelectron spectroscopy demonstrated that anion exchange dominated the AO7 removal, while MB was adsorbed via hydrophobic interaction between MB and DS. Density functional theory further confirmed the interaction, wherein the bonding distance was 1.622 Å between AO7 and 3D-MA-LDH’s layer. MB showed strong affinity toward DS with no dependence of bond connection to be stably anchored on the 3D-MA-LDH. In addition, the recyclability experiments exibited that 3D-MA-LDH could be stably reused for at least five times. This work provided a new approach for cleaning ionic dyes and broadened the application field of 3D- LDHs.

MORPHOLOGICAL AND CHEMICAL PROPERTIES OF SPHERICAL AND NEEDLE CALCIUM PHOSPHATE BIONS

Aim. To compare morphological properties, mineral, and organic profile of spherical calcium phosphate bions (SCPB) and needle calcium phosphate bions (NCPB) for the assessment of the CPB-specific endothelial toxicity in models of mild or severe hypercalcemia/hyperphosphatemia in the further studies.Methods. Both SCPB and NCPB were artificially synthesized employing blood-mimetic medium either moderately or significantly supersaturated of calcium and phosphorus salts. Size and shape of SCPB and NCPB were investigated by scanning and transmission electron microscopy and atomic force microscopy. Elemental analysis was performed utilizing energy-dispersive X-ray spectroscopy, atomic emission spectroscopy, and CHNSO analysis, functional groups were examined using Fourier-transform infrared spectroscopy and Raman spectroscopy while chemical formula was identified by X-ray powder diffraction analysis. Protein profile of SCPB and NCPB was screened employing sodium dodecyl sulfate polyacrylamide gel electrophoresis following silver staining.Results. SCPB were visualized as crystalline spherical spongeous particles of 80-200 nm diameter and mean diameter of around 120 nm while NCPB represented needle crystals of a similar diameter. Both SCPB and NCPB had similar crystallinity, surface charge and tended to form clusters of several particles. Furthermore, both SCPB and NCPB were composed of carbon, oxygen, hydrogen, nitrogen, calcium, and phosphorus, contained phosphate (PO4 3-), carbonate (CO3 2-), and hydroxyl (OH- ) functional groups, and consisted of hydroxyapatite (Ca10(PO4 )6 (OH)2 ) and carbonate-hydroxyapatite (Ca10(PO4)3 (CO3)3 (OH)2 ). In addition, protein profile of SCPB and NCPB was similar and notable for the abundant albumin and fetuin A levels.Conclusion. Having similar size, surface charge, extent of crystallinity, and chemical composition, SCPB and NCPB possess a different shape.

Determination of in Vitro and in Silico Indexes for the Modeling of Blood-Brain Barrier Partitioning of Drugs via Micellar and Immobilized Artificial Membrane Liquid Chromatography.

In the present work, 79 structurally unrelated analytes were taken into account and their chromatographic retention coefficients, measured by immobilized artificial membrane liquid chromatography (IAM-LC) and by micellar liquid chromatography (MLC) employing sodium dodecyl sulfate (SDS) as surfactant, were determined. Such indexes, along with topological and physicochemical parameters calculated in silico, were subsequently used for the development of blood-brain barrier passage-predictive statistical models using partial least-squares (PLS) regression. Highly significant relationships were observed either using IAM (r2 (n - 1) = 0.78) or MLC (r2 (n - 1) = 0.83) derived indexes along with in silico descriptors. This hybrid approach proved fast and effective in the development of highly predictive BBB passage oriented models, and therefore, it can be of interest for pharmaceutical industries as a high-throughput BBB penetration oriented screening method. Finally, it shed new light into the molecular mechanism involved in the BBB uptake of therapeutics.

Facile green synthesis of Pd/N-doped carbon nanotubes catalysts and their application in Heck reaction and oxidation of benzyl alcohol

Evenly dispersed Pd nanoparticles are facilely and successfully deposited on N-doped carbon nanotubes (Pd/N-CNTs) by employing sodium dodecyl sulfate (SDS) as a salt and polyvinylpyrrolidone (PVP) as both a surface modifier and a stabilizing agent. The presence of SDS and the amount of PVP have significant influences on the formation of evenly dispersed Pd/N-CNTs catalyst. No additional functionalization steps, reducing agents and stabilizers are required as usual to achieve the uniform deposition of Pd NPs over the N-CNTs surfaces. The as-synthesized Pd/N-CNTs catalyst is proved to be very active in the Heck reaction and can be reused at least for 5 times without significant loss of catalytic activity in the aerobic oxidation of benzyl alcohol.

Controlled Synthesis of Highly Crystallized Mesoporous Mn2 O3 and Mn3 O4 by Using Anionic Surfactants.

Mesostructured manganese oxide (Mn3 O4 ) is prepared by a soft-templating method employing sodium dodecyl sulfate (SDS) as a structure-directing agent. By removing the template from the as-prepared mesostructured Mn3 O4 by extraction or calcination, we successfully synthesized highly crystallized mesoporous Mn3 O4 or Mn2 O3 , respectively, with different crystalline structures.

Enhanced dielectric and energy storage performance of surface treated gallium ferrite/polyvinylidene fluoride nanocomposites

The ceramic–polymer nanocomposites composed of gallium ferrite (GFO) nanoparticles and employing sodium dodecylsulphate (SDS) as surfactant and polyvinylidene fluoride (PVDF) as matrix have been fabricated by solvent casting followed by hot-press technique.

Water-based high-performance polymer field effect transistors enabled by heat-assisted surfactant elimination

Environmentally benign processing technology of polymeric semiconductor is demonstrated to facilitate industrial application of organic electronics. By employing sodium dodecyl sulfate (SDS) as a surfactant and Poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) as a polymeric semiconductor, a water-borne colloid was synthesized and used for forming the active layer of a field effect transistor. Traditionally, this technology was not successful in realizing high charge carrier mobility, owing to difficulties in identifying an optimal temperature for eliminating the surfactant while maintaining the long-range-ordered π–π stacked structure of the semiconductors. In this work, by utilizing the liquid crystalline nature of the PBTTT, we identified the optimal thermal treatment condition (∼270°C), which is sufficient both for eliminating the SDS and stimulating a second phase transition of the PBTTT. As a result, the PBTTT nanoparticle film cast from the water-borne colloid was successfully sintered to form continuously π–π stacked polymeric semiconductor films, whose high charge carrier mobility of 0.19cm2/Vs, is comparable to those of organic solvents.

One-step synthesis of mesoporous sulfated zirconia nanoparticles with anionic template

Mesoporous sulfated zirconia nanoparticles have been synthesized by employing sodium dodecyl sulfate (SDS) as a template and a sulfating agent via one-step route, and the aforementioned materials were characterized by N2 adsorption-desorption, XRD, FT-IR, TEM as well as EDS. It was found that the SO42- anion, originated the hydrophilic head of template SDS, can be directly incorporated into zirconia to form superacid, and the corresponding formation mechanism was illustrated.

A New Mesoporous Magnesium Borate Microsphere Synthesized Using Sodium Dodecyl Sulfate as Template <sup></sup>

In this paper, we report a simple strategy for fabricating mesoporous magnesium borate (2MgO·B2O3) microspheres. We employed sodium dodecyl sulfate (SDS) in one system, as a template for the controlled growth of mesoporous 2MgO·B2O3microspheres. The products were characterized by XRD, SEM, TEM, EDS, N2sorption and FT-IR. SEM and TEM observations indicate magnesium borate products are composed of a large number of hollow microspheres, with diameters of 1.0~1.5 μm, which are in fact built from fibers with lengths of 100~150 nm. The N2sorption results show that the products have meso-structures. The average pore diameter is 27 nm. The BET surface area is about 53.03 m2/g, and the pore volume is 0.37 m3/g. It was found that SDS plays a key role for the formation of mesoporous structure. A possible mechanism was proposed to interpret the formation of the mesoporous structure. The mesopores will endow the hierarchical microspheres with novel application potentials.

A study on trypsin, Aspergillus flavus and Bacillus sp. protease inhibitory activity in Cassia tora (L.) syn Senna tora (L.) Roxb. seed extract.

BackgroundProteases play an important role in virulence of many human, plant and insect pathogens. The proteinaceous protease inhibitors of plant origin have been reported widely from many plant species. The inhibitors may potentially be used for multiple therapeutic applications in viral, bacterial, fungal diseases and physiological disorders. In traditional Indian medicine system, Cassia tora (Senna tora) is reportedly effective in treatment of skin and gastrointestinal disorders. The present study explores the protease inhibitory activity of the above plant seeds against trypsin, Aspergillus flavus and Bacillus sp. proteases.MethodsThe crushed seeds of Cassia tora were washed thoroughly with acetone and hexane for depigmentation and defatting. The proteins were fractionated by ammonium sulphate (0-30, 30-60, 60-90%) followed by dialysis and size exclusion chromatography (SEC). The inhibitory potential of crude seed extract and most active dialyzed fraction against trypsin and proteases was established by spot test using unprocessed x-ray film and casein digestion methods, respectively. Electrophoretic analysis of most active fraction (30-60%) and SEC elutes were carried employing Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Gelatin SDS-PAGE. Inhibition of fungal spore germination was studied in the presence of dialyzed active inhibitor fraction. Standard deviation (SD) and ANOVA were employed as statistical tools.ResultsThe crude seeds' extract displayed strong antitryptic, bacterial and fungal protease inhibitory activity on x-ray film. The seed protein fraction 30-60% was found most active for trypsin inhibition in caseinolytic assay (P < 0.001). The inhibition of caseinolytic activity of the proteases increased with increasing ratio of seed extract. The residual activity of trypsin, Aspergillus flavus and Bacillus sp. proteases remained only 4, 7 and 3.1%, respectively when proteases were incubated with 3 mg ml-1 seed protein extract for 60 min. The inhibitory activity was evident in gelatin SDS-PAGE where a major band (~17-19 kD) of protease inhibitor (PI) was detected in dialyzed and SEC elute. The conidial germination of Aspergillus flavus was moderately inhibited (30%) by the dialyzed seed extract.ConclusionsCassia tora seed extract has strong protease inhibitory activity against trypsin, Aspergillus flavus and Bacillus sp. proteases. The inhibitor in Cassia tora may attenuate microbial proteases and also might be used as phytoprotecting agent.

One-pot solvothermal route to self-assembly of cauliflower-shaped CdS microspheres

Nearly monodispersed cauliflower-shaped CdS microspheres were prepared through a simple one-step solvothermal route on a large scale by employing sodium dodecyl sulfate (SDS) as the surfactant. Images by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) indicate that cauliflower-shaped CdS microspheres with diameters in the range from 1.3 to 4.5 μm are assembled by nanoparticles with an average diameter of approximately 30 nm. The possible formation mechanism of the cauliflower-shaped CdS microspheres was also proposed. The photovoltaic activity of cauliflower-shaped CdS architectures has been investigated, indicating that the as-obtained CdS microspheres exhibited higher photovoltaic performance in comparison with CdS nanoparticles.

Low Activity and Poor Membrane Tethering for Rabbit Brain Cytochrome c Oxidase in Cholesterol-Copper Alzheimer's Model

Alzheimer's disease (AD) is a major cause of dementia and death in the elderly, but its etiology is poorly understood. In recent years, Sparks and Schreurs (2003) have developed a rabbit model which displays 12 AD characteristics; however, the activity of brain cytochrome c oxidase (COX), which is usually low in AD, has not yet been assessed. In this study, we assessed activity of brain COX for Sparks' model. New Zealand white rabbits were maintained on the specified cholesterol-copper diet for a 10-week period following which brain mitochondria were isolated. The activity of COX within the mitochondria was assessed by polarographic assay; we also evaluated the spectral properties of the mitochondria and employed sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to investigate their protein composition. Finally, we attempted to isolate COX and studied its subunit composition by SDS-PAGE. Polarographic assay revealed that compared to the controls, 44% of the rabbits on the cholesterol-copper diet had significantly decreased brain COX activity; on average, the V (max) of the high affinity site of mitochondria from the cholesterol-copper-fed rabbits was 26% lower than that of the controls. In addition, the difference spectra of brain mitochondria obtained from 33% of the rabbits raised on the cholesterol-copper diet, showed 35-40% diminished absorbance in the 430 nm region suggesting decreased concentration or reducibility of COX or another heme protein. SDS-PAGE analysis revealed that, for the rabbits raised on the cholesterol-copper diet, a number of COX subunits (VI-VII) were loosely held and easily lost during attempts to isolate the enzyme.

Determination of cationic neurotransmitters and metabolites in brain homogenates by microchip electrophoresis and carbon nanotube-modified amperometry

An electrophoretic method for simultaneous determination of catecholamines and their O-methoxylated metabolites on the microchip as well as in the capillary is presented. A complex separation system employing sodium dodecyl sulfate (SDS) micelles, dendrimers forming a second pseudostationary phase and borate complexation is needed for the satisfactory separation of the selected compounds on the short migration length. A carbon nanotube-modified working electrode has been applied for the sensitive amperometric detection with submicromolar detection limits. The applicability of this new method for the analytics of real samples is demonstrated by analysis of mouse brain homogenate on the microchip and human urine by capillary electrophoresis.

Determination of gentamicin in pharmaceutical formulations using peroxyoxalate chemiluminescent detection in flow-injection analysis

A simple and sensitive procedure for the determination of gentamicin is presented, based on the use of the peroxyoxalate chemiluminescent (PO-CL) system in presence of imidazole as a catalyst. The gentamicin has to be previously derivatized with o-phthaladehyde (OPA) in order to obtain a fluorophore, which participates in the PO reaction, producing a CL emission proportional to the gentamicin concentration. The method is developed by using a particular flow-injection analysis (FIA) manifold, employing sodium dodecyl sulfate (SDS) micellar medium as a carrier in order to avoid the degradation of PO in water. The optimization of the instrumental and chemical variables affecting the CL reaction was rigorously carried out by using experimental design methodology. The method has been successfully applied to pharmaceutical formulations.

Cell-free xenogenic vascular grafts fixed with glutaraldehyde or genipin: In vitro and in vivo studies

Chronic rejection of arterial xenografts results in aneurysmal dilation, due to immune mediated processes. To minimize the immunologic degradation of the graft, a cell-extraction process employing sodium dodecyl sulfate (SDS) was used in the study to remove the cellular components in bovine carotid arteries. To further reduce their immunogenicity, the acellular arteries were fixed with glutaraldehyde (A-GA) or genipin (A-GP). The in vitro properties of all test samples were analyzed. Additionally, the in vivo performance of the heparinized A-GA and A-GP grafts (H-A-GA and H-A-GP) was evaluated in a canine model. It was found that the SDS treatment effectively removed cells from the arterial wall, but the main structures of the extracellular matrix were preserved with a portion of the water-soluble glycosaminoglycans removed. After cell extraction, the elastic lamellae in the media became straightened, and thus made the tissue less extensile. The heparinized tissues significantly reduced platelet adhesion. At retrieval, all implanted grafts were patent and not dilated. Chronic inflammatory response surrounding the implants was observed. However, fixation of acellular tissues by glutaraldehyde or genipin inhibited immune cell penetration into the media and limited tissue degradation, and therefore prevented the arterial wall from dilation. Nevertheless, the H-A-GP graft was superior to the H-A-GA graft in completeness of endothelialization on its luminal surface, and thus precluded thrombus formation.

Separation and determination of lignans from seeds of Schisandra species by micellar electrokinetic capillary chromatography using ionic liquid as modifier

In this paper, a micellar electrokinetic chromatographic (MEKC) method using ionic liquid as modifier for the quantification of the active components of lignans found in the medicinal herbs Schisandra species was developed for the first time. Preliminary investigations employing sodium dodecyl sulfate (SDS) as surfactant did not lead to the necessary resolution of the studied compounds, the addition of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF 4) to the SDS micellar system resulted in the complete separation of all the compounds. The effects on the separation by several parameters such as BMIM-BF 4 and SDS concentration, applied voltage, background electrolyte pH and concentration, were evaluated. Under the optimal conditions (5 mM borate-5 mM phosphate buffer in the presence of 20 mM SDS and 10 mM BMIM-BF 4, pH 9.2, applied voltage 25 kV and detection at 254 nm), the method successfully applied to the determination of lignans in extracts of Schisandra chinensis (Turcz.) Baill. and Schisandra henryi C.B. Clarke in less than 13 min. The separation mechanism was also discussed.