Use Of Sodium Dodecyl Sulfate Research Articles

Simultaneous determination of andrographolide and dehydroandrographolide in Andrographis paniculata and Chinese medicinal preparations by microemulsion electrokinetic chromatography

The present paper describes the development of a microemulsion electrokinetic chromatographic (MEEKC) method for simultaneous determination of andrographolide and dehydroandrographolide in traditional Chinese medicines and Chinese medicinal preparations. The MEEKC method involved the use of sodium dodecyl sulfate (SDS) as surfactant, heptane as organic solvent and butan-1-ol as co-solvent. The effect of temperature and pH of running buffers on separation were examined. The optimized conditions (heptane 0.81% (w/w), SDS 3.31% (w/w), butan-1-ol 6.61% (w/w) and 10 mM sodium tetraborate buffer, pH 9.2) allowed a useful and good reproducible separation of the studied analytes to be achieved.

Capturing SDS-treated biotinylated protein and peptide by avidin functional affinity electrophoresis with or without SDS in the gel running buffer

Avidin functional affinity electrophoresis (AFAEP) is a new method of affinity electrophoresis. In this technique, bifunctional linker glutaraldehyde is added to the polyacrylamide gel solution to embed avidin within the gel matrix by interaction with the amino/amide groups. Samples are heated with triglycine sodium dodecyl sulfate (SDS) sample buffer to ensure that biotinylated proteins biotinylated peptides are negatively charged and migrate electrophoretically toward the cathode through the avidin zone regardless of their p I values. The AFAEP method allows the capture and concentration of biotinylated proteins or biotinylated peptides irrespective of the use of SDS in both the sample buffer and the gel running buffer.

Use of sodium dodecyl sulfate and zinc sulfate as reference substances for toxicity tests with the mussel Perna perna (Linnaeus, 1758) (Mollusca: Bivalvia)

Effects of anthropogenic pollution have been observed at different trophic levels in the oceans, and toxicity tests constitute one way of monitoring these alterations. The present assay proposes the use of two reference substances, sodium dodecyl sulfate (SDS) and zinc sulfate, for Perna perna larvae. This common mussel on the Brazilian coast is used as a bioindicator and is of economic interest. The chronic static embryo–larval test of short duration (48 h) was employed to determine the NOEC, LOEC, and IC 50 for SDS and zinc sulfate, as well as the coefficient of variation. Salinity, pH and un-ionized ammonia (NH 3) and dissolved oxygen (DO) concentrations were measured to monitor water quality. The results demonstrated that the main alterations in veliger larvae are the development of only one shell, protruded mantle, malformed shell, formation of only part of a valve, clipped edges, uneven sizes and presence of a concave or convex hinge. NOEC values were lower than 0.25 mg L −1 for zinc sulfate and 0.68 mg L −1 for SDS. The coefficient of variation was 17.63% and 2.50% for zinc sulfate and SDS, respectively.

Membrane proteome analysis of the green‐sulfur bacterium Chlorobium tepidum

An extensive proteomic approach relies on the possibility to visualize and analyze various types of proteins, including membrane proteins, which are rarely detectable on two-dimensional electrophoresis gels. In this study, different methods were employed for the enrichment of membrane proteins from Chlorobium tepidum prior to analysis with two-dimensional electrophoresis (2-DE). Isolated membranes were solubilized with Triton X-100 and from the supernatant we identified 58 unique proteins. The use of ionic sodium dodecyl sulfate (SDS) for protein solubilization, combined with acetone precipitation, resulted in an improved 2-DE pattern and the total number of the identified proteins was increased to 117. The use of acetone for protein precipitation improved the results by extracting compounds potentially deleterious to the resolution of 2-DE. However, the additional proteins detected by the use of SDS are in the majority more difficult to solubilize than less hydrophobic proteins. Further our attempts for selective extraction of the outer membrane proteins using the acid glycine method allowed the identification of 37 proteins of which 14 were predicted to have a signal sequence indicating their localization in the periplasmic space or in the outer membrane.

Effects of common surfactants on protein digestion and matrix-assisted laser desorption/ionization mass spectrometric analysis of the digested peptides using two-layer sample preparation.

While surfactants are commonly used in preparing protein samples, their presence in a protein sample can potentially affect the enzymatic digestion process and the subsequent analysis of the resulting peptides by mass spectrometry. The extent of the tolerance of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to surfactant interference in peptide analysis is very much dependent on the matrix/sample preparation method. In this work the effects of four commonly used surfactants, namely n-octyl glucoside (OG), Triton X-100 (TX-100), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) and sodium dodecyl sulfate (SDS), for biological sample preparation on trypsin digestion and MALDI-MS of the resulting digest are examined in detail within the context of using a two-layer method for MALDI matrix/sample preparation. Non-ionic and mild surfactants, such as OG, TX-100 or CHAPS, are found to have no significant effect on trypsin digestion with surfactant concentrations up to 1%. However, TX-100 and CHAPS interfere with the subsequent peptide analysis by MALDI-MS and should be removed prior to peptide analysis. OG is an MS-friendly surfactant and no effect is observed for MALDI peptide analysis. The effect of SDS on trypsin digestion in terms of the number of peptides generated and the overall protein sequence coverage by these peptides is found to be protein dependent. The use of SDS to solubilize hydrophobic membrane proteins, followed by trypsin digestion in the presence of 0.1% SDS, results in a peptide mixture that can be analyzed directly by MALDI-MS. These peptides are shown to provide better sequence coverage compared with those obtained without the use of SDS in the case of bacteriorhodopsin, a very hydrophobic transmembrane protein. This work illustrates that MALDI-MS with the two-layer sample preparation method can be used for direct analysis of protein digests with no or minimum sample cleanup after proteins are digested in a solution containing surfactants.

Separation of benzene, toluene, ethylbenzene, and xylenes by micellar electrokinetic capillary chromatography

The use of sodium dodecyl sulfate, urea, ß‐cyclodextrin, and methanol as additives to the electrophoretic medium containing a Na2HPO4‐boric acid buffer in the micellar electrokinetic capillary chromatography of benzene, toluene, ethylbenzene, and three isomers of xylene (collectively known as BTEX) was investigated. The results showed that with the addition of sodium dodecyl sulfate only, higher selectivity and sensitivity and shorter migration time could be achieved, which consequently resulted in better separation of BTEX studied. For this buffer system, good linearity (R2>0.99) was found over the range of 5 to 500 μg m1‐1 for individual BTEX compound and separation time of less than 5 min for BTEX was possible.

Use of sodium dodecyl sulfate as an antifouling and homogenizing agent in the direct determination of heavy metals by anodic stripping voltammetry.

The effectiveness of the anionic surfactant sodium dodecyl sulfate (SDS) for suppressing adsorption interferences in anodic stripping voltammetry (ASV) was investigated. The samples included fruit juices, wine, beer, milk powder and waste water, and the analytes were cadmium, lead and copper. In most of the samples, the ASV signals were severely depressed or even absent due to electrode fouling, but addition of SDS in concentrations up to 10 g L(-1) proved effective in restoring the ASV response. By using SDS as an interference suppressor, the content of lead and copper in a milk powder reference material was determined, and the results were in agreement with the certified values. In this determination, which could not have been performed without SDS, the surfactant also served as a homogenizing agent, preventing separation of the sample components. The effect of SDS was explained by the interaction of the surfactant with the electrode surface and with the constituents of the sample matrix.

Microemulsion electrokinetic chromatography for the analysis of green tea catechins: effect of the cosurfactant on the separation selectivity.

Microemulsion electrokinetic chromatography (MEEKC) was applied to the separation of six catechins and caffeine, the major constituents of the green tea. The developed methods involved the use of sodium dodecyl sulfate (SDS) as surfactant, n-heptane as organic solvent and an alcohol as cosurfactant. The separations were performed under acidic conditions (pH 2.5 phosphate buffer, 50 mM) to ensure good stability of the catechins, with reversed polarity (anodic outlet). The effect of the alcohol nature on the MEEKC selectivity was evaluated; nine alcohols were used as cosurfactant: 1-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and cyclohexanol. The migration order of (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-gallocatechin (GC), (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG), caffeine and theophylline was significantly affected by the alcohol used as cosurfactant. Using nine microemulsions, four different selectivities were achieved: A (cyclohexanol); B (2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol); C (1-butanol, 1-pentanol, cyclopentanol); D (tert-butanol). MEEKC methods, based on 2-hexanol and cyclohexanol as cosurfactant were validated and successfully applied to the analysis of catechins and caffeine in commercial green tea products.

Influence of surfactant molecules as air-entraining agent for bone cement macroporosity.

Calcium phosphate bone cements (CPBCs) represent a potential synthetic alternative to bone-graft materials in bone surgery applications. CPBCs are biocompatible, bioresorbable, and slowly are replaced by new bone in vivo. However, CPBCs do not develop a macroporosity during setting that would allow fast bone ingrowth and good osteointegration of the implant. For this reason, recent research has approached the problem of inducing macroporosity inside the bone cement without influencing its normal setting. In this study, a new method for obtaining injectable macroporous CPBCs is proposed. It is based on the use of sodium dodecyl sulphate (SDS) as an air-entraining agent. The results have shown that the liquid-to-powder ratio and the SDS concentration, as well as the diameter and the interconnectivity of the macropores, can control the micro- and macroporosity. This new technology can be used to develop and optimize new commercial products for osteoporotic bone filling applications. Furthermore, the presented method also can be used at low temperatures before an operation to produce preformed implants to fit the particular needs of a patient.

Analysis of catechins in extracts of Cistus species by microemulsion electrokinetic chromatography

A microemulsion electrokinetic chromatographic (MEEKC) method was developed for the separation of six catechins, specific marker phytochemicals of Cistus species. The MEEKC method involved the use of sodium dodecyl sulfate (SDS) as surfactant, heptane as organic solvent and butan-1-ol as co-solvent. In order to have a better stability of the studied catechins, the separation was performed under acidic conditions (pH 2.5 phosphate buffer). The effects of SDS concentration and of the amount of organic solvent and co-solvent on the analyte resolution were evaluated. The optimized conditions (heptane 1.36% (w/v), SDS 2.31% (w/v), butan-1-ol 9.72% (w/v) and 50 m M sodium phosphate buffer (pH 2.5) 86.61% (w/v)) allowed a useful and reproducible separation of the studied analytes to be achieved. These conditions provided a different separation profile compared to that obtained under conventional micellar electrokinetic chromatography (MECK) using SDS. The method was validated and applied to the determination of catechin and gallocatechin in lyophilized extracts of Cistus incanus and Cistus monspeliensis.

Determination of the sensitising activity of the rubber contact sensitisers TMTD, ZDMC, MBT and DEA in a modified local lymph node assay and the effect of sodium dodecyl sulfate pretreatment on local lymph node responses

A modified local lymph node assay (LLNA) was used to determine the sensitising activity of four chemicals used for the production of natural rubber latex products. Tetramethylthiuramdisulfide (TMTD), 2-mercaptobenzothiazole (MBT) and zincdimethyldithiocarbamate (ZDMC), three moderate human sensitisers, and diethylamine (DEA) a known human sensitiser, were epicutaneously administered on the ear and the proliferating activity in the draining (auricular) lymph node (LN) was determined by ex vivo 3H-thymidine incorporation. Consistent results were obtained for TMTD and ZDMC with stimulation indices (SI) above 3, identifying these compounds as sensitiser, while for DEA and MBT inconsistent results were obtained. For all parameters determined such as LN weight, LN cell number, cell proliferation per 2×10 6 cells, and cell proliferation per LN statistical significant increases were observed. The SI, expressed as cellular proliferation per LN or per animal (left and right LN combined), was the most sensitive parameter with an optimum at day 5 after start of treatment. Furthermore, we investigated whether the use of sodium dodecyl sulfate (SDS) was able to enhance weak responses in the LLNA. SDS treatment with dosages of 10% and higher resulted in a SI above 3, while a dosage of 1% SDS showed no activity. Pretreatment with 1% SDS 1 h before application of the rubber chemicals enhanced the responses to these chemicals consistently, identifying also DEA and MBT as sensitisers. Our results indicate that SDS had synergistic activity on the LN responses of the administered rubber chemicals in the LLNA. For the moderately responding sensitisers TMTD and ZDMC both IFN-γ and IL-4 production was observed. For the weakly responding sensitisers DEA and MBT both IFN-γ and IL-4 cytokine production was only observed after pretreatment of the animals with 10% SDS. For 10% and 20% SDS, inducing approximately a SI of 20 in the LLNA, no induction of cytokines was observed.

Antigen Retrieval on Ultrathin Cryosections.

We have studied two different monoclonal antibodies that behave poorly for the immunocytochemical localization of caveolin-1 and caveolin-2 in paraformaldehyde fixed tissue. Treatment of tissue sections with sodium dodecyl sulfate (SDS) led to enhanced immunocytochemical detection of antigens with each of these antibodies. In this study, we have focused on the use of SDS for antigen retrieval using ultrathin cryosections. Herein, we show that SDS treatment can be applied to ultrathin cryosections without deleterious effects and can be used for high-resolution immunofluorescence detection of caveolin-1 and -2.

Heparin-glutathione III: study with fluorescent probes as indicators of membrane status of bull sperm.

Sperm obtained from bull epididymes were used to validate in vitro the effect of heparin and reduced glutathione on sperm membrane status, with the use of sodium dodecyl sulfate (SDS) and Triton X-100 in the presence of propidium iodide (IP) and diacetate fluorescein (FDA). The metabolic activities of treated sperm were qualitatively monitored using an alamar Blue Redox fluorescence indicator. Heparin did not damage the sperm plasma membrane, whereas GSH and SDS at 26 h of incubation dissolved the plasma membrane and the acrosome. On the other hand, at time zero, Triton X-100 showed 75% of sperm stained with IP, indicating plasma membrane damage. Results validated by electron microscopy of thin sections of treated sperm showed complete lack of the membrane, acrosome, and postacrosomal membrane system with 0.01% Triton X-100. Extracellular 15 mM GSH completely disappeared the plasma membrane over the sperm nucleus, leaving the postacrosomal membrane system and nucleus without apparent damage. The metabolic activity was supported over 52 h of incubation in any of the incubation systems tested, including Triton X-100, which showed a spermaticide effect. The authors propose that membrane damage does not mean they are dead, no matter the vital stain employed, and also that FDA-IP staining can be used as a fluorescent marker of sperm plasmatic membrane permeabilization and nuclear swelling.

The use of solution calorimetry with micellar solvent systems for the detection of polymorphism

The presence of multiple polymorphic forms in seven batches of raw material of a model compound having poor wettability properties (cimetidine) was studied by solution calorimetry. Due to the large number of polymorphic forms described in the literature (‘Gazz. Chim. Ital., 109 (1979) 535’; ‘J. Pharm. Sci., 73 (1983) 1436’; ‘J. Pharm. Biomed. Anal., 3 (1985) 303’) and its poor wettability characteristics, cimetidine was chosen as a model compound to illustrate the possible use of solution calorimetry in the detection of polymorphism using surfactant systems as solvents for dissolution. Due to the closeness of the melting points of the different polymorphic forms of cimetidine, DSC was not the best investigational tool. As initially suspected, the measurement of enthalpy of solution values in water of the cimetidine batches was not possible. However, the use of sodium dodecyl sulfate (SDS) and polysorbate 20 (Tween 20®) at concentrations above their respective cmc values permitted the detection of significant differences in enthalpy of solution among several batches. The presence of different polymorphic forms was confirmed by microscopy, X-ray powder diffractometry, and Fourier transform infrared spectroscopy.

Alkylation kinetics of proteins in preparation for two-dimensional maps: a matrix assisted laser desorption/ionization-mass spectrometry investigation.

All existing protocols for protein separation by two-dimensional (2-D) gel electrophoresis require the full reduction, denaturation, and alkylation as a precondition for an efficient and meaningful separation of such proteins. Existing literature provides a strong evidence to suggest that full reduction and denaturation can be achieved in a relatively short time; the same thing, however, can not be said for the alkylation process, which the present study shows that more than 6 h are required for a complete alkylation. We have used matrix assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS) to monitor protein alkylation by iodoacetamide over the period 0-24 h at pH 9. The present, fast and specific MS method provided clear indication on the extent and speed of alkylation which reached approximately 70% in the first 2 min, yet the remaining 30% resisted complete alkylation up to 6 h. The use of sodium dodecyl sulfate (SDS) during the alkylation step resulted in a strong quenching of this reaction, whereas 2% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) exerted a much reduced inhibition. The implications of the present measurements on 2-D gel analysis in particular and proteomics in general are discussed.

Effect of strong detergents and chaotropes on the detection of proteins in two-dimensional gels.

The solubilization of a particular protein is mandatory for its subsequent resolution and detection in two-dimensional gels. However, the extraction solutions, that are compatible with the first-dimensional separation step, such as urea and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), do not solubilize all proteins in a sample. We studied the effect of various common, strong detergents and chaotropes, widely used as solubilizing agents, such as sodium dodecyl sulfate, lithium dodecyl sulfate and guanidine hydrochloride, on the solubilization of the total and membrane proteins of the bacterium Haemophilus influenzae. The proteins solubilized with each system were analyzed by two-dimensional electrophoresis and these of interest were identified by matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS). Use of sodium dodecyl sulfate, lithium dodecyl sulfate or guanidine hydrochloride for the solubilization of total proteins of the microorganism resulted in the detection of several additional spots, representing mainly outer membrane proteins, in comparison with those detected in the soluble protein fraction. Solubilization of the proteins of the cell envelope fraction with sodium dodecyl sulfate did not result in a more efficient protein detection when compared to the extraction with the urea/CHAPS system. When the dry immobilized pH gradient strips were rehydrated in a solution containing the proteins of the membrane fraction solubilized with sodium dodecyl sulfate or lithium dodecyl sulfate, a larger number of protein spots were detected in comparison with strips that were rehydrated in the urea/CHAPS solution. However, no improvement was observed in comparison with protein application in sample cups. The additional proteins detected with the use of strong detergents and chaotropes are in the majority difficult to solubilize and less hydrophobic proteins.

Isolation and curing of the Klebsiella pneumoniae large indigenous plasmid using sodium dodecyl sulphate

The ability of Klebsiella pneumoniae (NCTC, CL687/80) to produce and, in turn, excrete glutamate has been equated with the presence of a large indigenous plasmid with an apparent molecular mass in the region of 96 ± 2 kbp ( n = 6). Unlike mitomycin C, novobiocine and ethidium bromide (curing agents), the use of sodium dodecyl sulphate (SDS) proved very effective in curing the plasmid with a relatively high frequency (6.25 × 10 –4). Furthermore, the absence of isocitrate dehydrogenase (ICDH) activity in the cured strain strongly suggests that the structural gene encoding ICDH in this organism, in sharp contrast to all known ICDHs, is plasmid-encoded. Moreover, the SDS-based protocol reported for the isolation of the K. pneumoniae indigenous plasmid has proven successful with other organisms including Pseudomonad and Corynebacteria, as well as in recombinant strains of Escherichia coli.

Polytrauma induces increased expression of pyruvate kinase in neutrophils

Polytrauma (PT) leads to systemic activation of polymorphonuclear neutrophils (PMNs). Organ damage commonly found in these patients is ascribed to respiratory bursts of activated PMNs. With the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, PMN extracts from PT patients were found to contain a clear protein band not seen in control PMNs from healthy volunteers. This band was identified by amino acid sequencing and Western blotting as pyruvate kinase (PK). Enzymatic assays revealed a 600-fold increase in PK activity in PMNs of PT patients, with the highest levels occurring between the fifth and seventh posttraumatic day. In lymphocytes, no such increase was detectable. As PK is a major regulatory enzyme in glycolysis, glucose-dependent lactate production in PMNs from PT patients was assayed. These cells showed a higher glycolytic lactate production than controls. It was additionally demonstrated that acute activation of respiratory burst activity depends mainly on breakdown of glucose to lactate via the pentose-phosphate pathway and glycolysis. In PMNs from PT patients, this glucose-dependent respiratory burst activity was more than twofold higher than in controls. The increase in expression and activity of PK in PMNs from PT patients may contribute to the high glucose-dependent respiratory burst activity seen in these cells.

Use of sodium dodecyl sulphate for stimulation of biodegradation of n-alkanes without residual contamination by the surfactant

The capacity of a range of aliphatic alkanes (C 6–C 16), intermediates of n-decane oxidation and sodium dodecyl sulphate (SDS) to induce decane-mineralization activity in the cells of Pseudomonas C12B was compared with that for n-decane. The comparison on quantitative basis had two serious limitations: low solubility of tested inducers in aqueous solutions and their toxicity to bacterial cells. Carbon chain length and the presence of hydroxyl group were the important factors for induction activity. However, presence of hydroxyl groups at both ends of alkyl chain prevented the induction of decane-mineralization activity. Good induction activity by SDS was caused either by the presence of free end of alkyl chain, or by bacterial hydrolysis of sulphate group to yield alcohol, which in turn served as true inducer. The presence of SDS in the culture medium with n-decane as main source of carbon and energy accelerated the growth of Pseudomonas C12B. SDS disappeared from the culture medium in early stages of cultivation suggesting preferential degradation by the bacterium, while the consumption of n-decane was accelerated. This may be associated with the capacity of SDS to induce decane-mineralization system in Pseudomonas C12B and/or with the ability of SDS to stimulate the surface attachment of competent bacteria resulting in the close proximity of the cells with alkane droplets, and thus, enhanced breakdown of the hydrocarbon pollutant.

Highly Enantioselective Hydrogenation of Enamides and Itaconic Acid in Water in the Presence of Water-Soluble Rhodium(I) Catalyst and Sodium Dodecyl Sulfate

The water-soluble cationic Rh complexes, such as [Rh(α-d-glucopyranosyl-(1,1)-2,3-di-O-(diphenylphosphino)-α-d-glucopyranoside)(cod)]BF4 (1) and [Rh(β-d-glucopyranosyl-(1,1)-2,3-di-O-(diphenylphosphino)-β-d-glucopyranoside)(cod)]BF4 (2) bearing free hydroxy groups, are effective catalysts in the asymmetric hydrogenation of various enamides and itaconic acid (up to 99.9% ee) in water in the presence of sodium dodecyl sulfate (SDS) (7.5 × 10-3 to 1.0 × 10-1 M). The hydrogenation of methyl (Z)-α-acetamidocinnamate in water using the corresponding Rh complexes of triflate (6) and d-camphor-10-sulfonate (7), prepared separately, results in a formation of the product of the same enantioselectivity (48% ee), but the use of SDS can reduce the amount of the catalyst and improve the enantioselectivity to 81% ee. These results show that the counteranions do not directly influence the enantioselectivity. Although the effect of SDS on the enhancement of enantioselectivity remains speculative, the formation of micelle ...