Incorporation Of Sodium Dodecyl Sulfate Research Articles

Fabrication of α-MnO2/Fe-Mn binary oxide nanocomposite as an efficient adsorbent for the removal of methylene blue from wastewater

The development of the safe and cost-effective technologies for treating the dye-polluted wastewater has been a significant focus of researchers. In the light of this, α-MnO2/Fe-Mn binary oxide (α-MnO2/Fe-Mn BO) nanocomposite has been synthesized by a co-precipitation method. It was characterized by the FT-IR, XRD, BET, SEM, EDX, and TEM. The results indicated that the nanocomposite has a spheroid-like surface, a surface area of 92.954 m2/g and an average pore diameter of 2.39 nm. It was used as an adsorbent for the removal of methylene blue (MB) dye from an aqueous medium. The batch experiment revealed that 0.013 g of the nanocomposite can remove 98 % of MB (12.71 mg/L) in 30 min. The pH of the medium was the dominant factor in MB adsorption, where the highest removal efficiency was obtained at pH 4. Incorporation of sodium dodecyl sulfate (SDS) and NaCl decreased the MB adsorption. The adsorption process followed the pseudo-second-order and Elovich kinetic models. The results also fitted well with the Langmuir and Dubinin-Radushkevich (D-R) adsorption models. The maximum adsorption capacity was 89.63 mg/g at 30 °C and the nanocomposite showed good separation and regeneration properties. The removal efficiency decreased by about 20 % through five cycles. The α-MnO2/Fe-Mn BO is therefore considered a promising adsorbent for dyes owing to its high adsorption capacity, high chemical stability, good reusability, and simple synthesis procedure.

Identification of intracellular cadmium transformation in HepG2 and MCF-7 cells

It is of significance to elucidate or understand the intracellular transformation & migration behaviors of heavy metals in specific cells. Herein, we report the fast and efficient separation of cadmium-metallothioneins (Cd-MTs) and Cd2+in cell lysate by a short column capillary electrophoresis (SC-CE), followed by coupling with inductively coupled plasma mass spectrometry (ICP-MS) to facilitate the speciation of intracellular cadmium species. The incorporation of sodium dodecyl sulfate (SDS) in running buffer significantly reduces the peak width of Cd2+from 170 s to 26 s in the electrophoretogram, causing a 5.3-fold improvement on the sensitivity. Linear ranges of 0.5–50 mg L−1,0.056–5.6 mg L−1 and 0.1–10 mg L−1 are achieved for MTs, Cd-MTs (Cd) and Cd2+, respectively, along with detection limits of 0.013 mg L−1 for Cd-MTs (Cd) and 0.020 mg L−1 for Cd2+. The transformation of cadmium in HepG2 and MCF-7 cells is evaluated after their incubation with Cd2+ reinforced culture medium. Intracellular free Cd2+ cation and Cd-MTs are identified, along with Cd2+ transformation to Cd-glutathione (GSH) adduct/complex, as further demonstrated by ESI-MS.

Disruption of human stratum corneum lipid structure by sodium dodecyl sulphate.

Surfactants are major ingredients of body soaps and cleansers, and such harsh ones have been demonstrated to damage the skin. Stratum corneum (SC), the outermost barrier of the skin layer, is rich in intercellular lipids. This lipid structure can be disrupted by surfactants, impairing the barrier function of the skin. Thus, we investigated the surfactant-induced disruption of the intercellular lipid structure of human SC at the molecular level using synchrotron X-ray diffraction. SC samples from the breast of female Caucasians were treated with sodium dodecyl sulphate (SDS) and analysed by small-angle and wide-angle X-ray diffraction. We found that an aqueous SDS solution affected the long lamellar structure, which became disorganized. The final disordered lipid state was reached through two or more types of structural change. We propose that the disordered lipid state results from incorporation of SDS into the long lamellar structure. In contrast, the lattice constants in the short lamellar and the hydrocarbon-chain packing structures remained almost unchanged after SDS treatment. We conclude that the disruption of the long lamellar structure plays a key role in the damage to the SC caused by detergents. To our knowledge, this is the first report to clarify the details of the disorganization of the intercellular lipid structure upon surfactant application. The knowledge obtained herein may allow the development of skin restoration methods and cleanser products that do not affect skin barrier functions.

Effects of Sodium Dodecyl Sulfate as a Co-Adsorbate on the Performance of Dye-Sensitized Solar Cells.

As a surface modifier, sodium dodecyl sulfate (SDS), was applied to dye-sensitized solar cells (DSSCs), and its effects on the photovoltaic performance of the solar cells were investigated. When the SDS was co-adsorbed with dye (N719) onto TiO2 surface, the DSSCs with SDS showed an increase in short-circuit current (Jsc), open-circuit voltage (Voc) and fill factor, leading to a considerable improvement of over 23% in power conversion efficiency, compared to the reference cell without SDS. Incorporation of SDS on TiO2 surface induced longer lifetime of electrons injected from excited dyes to conduction band of TiO2, leading to an increase in the electron collection efficiency and thus an enhancement in Jsc. The longer lifetime by a suppression of the interfacial charge recombination could also contribute to an increment in Voc.

Physical properties of emulsion-based hydroxypropyl methylcellulose/whey protein isolate (HPMC/WPI) edible films

The objective of this research was to study the effect of the film microstructure of oil-in-water emulsions stabilized by hydroxypropyl methyl cellulose/whey protein isolate (HPMC/WPI) with or without sodium dodecyl sulfate (SDS) over physical properties of HPMC/WPI emulsion-based films. The films were prepared with different HPMC/WPI-oil-SDS combinations (%w/w for 100g of dispersion): HPMC; WPI; HPMC/1WPI-0.5-SDS; HPMC/1WPI-1; HPMC/2WPI-0.5; HPMC/2WPI-1-SDS. Physical properties of films were evaluated. The results showed no statistical differences (p>0.05) between the thicknesses of EFs (0.156±0.004mm). The effect of oil content and incorporation of SDS showed the inverse trend for WI and ΔE, the increasing order of change, for WI and ΔE, among the formulation evaluated was: HPMC/1WPI-1>HPMC/2WPI-0.5>HPMC/2WPI-1.0-SDS≈HPMC/1WPI-0.5-SDS≈WPI>HPMC for WI and HPMC/1WPI-0.5-SDS>HPMC/2WPI-1.0-SDS>HPMC/2WPI-0.5>HPMC/1WPI-1 for ΔE, respectively. The addition of oil and SDS decreased the TS and EB, because oil addition into EF induces the development of structural discontinuities, producing an EF with less chain mobility, and consequently, with less flexibility and resistance to fracture.

Molecular dynamics of the interaction of anionic surfactants with liposomes

The time dependent molecular interactions of sodium dodecyl sulfate (SDS) with dipalmitoylphosphatidylcholine (DPPC) liposomes were studied using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. In particular, the ATR spectra provided information on the dynamic amount of SDS incorporated and DPPC expelled in the DPPC structure along with structural information on the molecular nature of the SDS/DPPC assemblies. It was found that the uptake of SDS was always mirrored by the ejection of DPPC molecules from the liposomes and that the incorporation of SDS followed two routes; SDS intercalated into the DPPC liposomes and SDS was bound electrostatically to the charged surface of the DPPC liposome.

Observing the Solubilization of Lipid Bilayers by Detergents with Optical Microscopy of GUVs

The solubilization of lipid bilayers by detergents was studied with optical microscopy of giant unilamellar vesicles (GUVs) composed of palmitoyl oleoyl phosphatidylcholine (POPC). A solution of the detergents Triton X-100 (TX-100) and sodium dodecyl sulfate (SDS) was injected with a micropipette close to single GUVs. The solubilization process was observed with phase contrast and fluorescence microscopy and found to be dependent on the detergent nature. In the presence of TX-100, GUVs initially showed an increase in their surface area, due to insertion of TX-100 with rapid equilibration between the two leaflets of the bilayer. Then, above a solubility threshold, several holes opened, rendering the bilayer a lace fabric appearance, and the bilayer gradually vanished. On the other hand, injection of SDS caused initially an increase in the membrane spontaneous curvature, which is mainly associated with incorporation of SDS in the outer layer only. This created a stress in the membrane, which caused either opening of transient macropores with substantial decrease in vesicle size or complete vesicle bursting. In another experimental setup, the extent of solubilization/destruction of a collection of GUVs was measured as a function of either TX-100 or SDS concentration.

Improved methods for isolating DNA from Ostertagia ostertagi eggs in cattle feces

A multiplex PCR assay for differentiating strongyle eggs from cattle has recently been described; however, the egg disruption and DNA extraction procedures, though effective, are inadequate for large studies or clinical application. The purpose of this research was to evaluate methods for disrupting trichostrongyle eggs, then assess commercial kits for extracting egg DNA using Ostertagia ostertagi as a model species. Egg disruption procedures tested included probe sonication, bath sonication, bead beating, boiling, microwaving, proteinase K/SDS digestion, freezing, and various combinations of the above with the incorporation of sodium dodecyl sulfate. These procedures were evaluated in conjunction with four commercial DNA extraction kits: DNA Stool mini kit and DNeasy Plant kit (Qiagen), Fast DNA kit (QBiogene), and the MAP extraction kit (Tetracore). Results showed that egg disruption was best accomplished with the bead beater and ceramic beads, resulting in 100% disruption within 1 min. When DNA extraction was preceded by the isolation of eggs from feces, all procedures except the Fast DNA kit produced PCR-ready DNA from at least two eggs. The DNeasy Plant kit allowed consistent detection of DNA released from one egg. Due to the morphological similarities among trichostrongyle eggs in ruminants, strongyle eggs in equids, and hookworm eggs, the methods described herein may have broad application to other nematodes.

Swelling and network parameters of crosslinked thermoreversible hydrogels of poly( N-ethylacrylamide)

Samples of Poly( N-ethylacrylamide) (PEA) have been synthesized by free radical polymerization in water using N, N′-methylene bis-acrylamide (BIS) as crosslinker. Hydrogels obtained by swelling them in water, 15 wt% KCl and 1 wt% sodium dodecyl sulphate (SDS) were examined by gravimetric, dimensional and compression–strain measurements to afford values of swelling ratio, polymer–solvent interaction parameters, elastic moduli and effective crosslinking density ν e. Crosslinking inefficiency is evidenced by the low value (0.23) of ν e relative to the theoretical crosslinking density ν t based on the content of BIS in the synthesis. A small but finite extrapolated value of ν e at ν t = 0 is indicative of hydrophobic physical interactions. In water at 298 K increasing the content of BIS leads to a decrease in swelling and increases in values of elastic moduli and polymer–water interaction parameter. At a fixed content of BIS the values of ν e and the elastic moduli exhibit an unusual increase with temperature, the crosslinking thus being thermally reversible. It is proposed that this results from a balance between hydrophobic interaction and breakage of hydrophilic hydrogen bonding. Although KCl in the medium decreases the swelling compared with that in water, the opposite effect occurs on incorporation of SDS, which is assumed to confer some polyelectrolyte character to the PEA chains. The finding, that these two swelling media reduce the values of ν e and elastic moduli cf the value in water, has not been resolved satisfactorily.

Stability aspects of salmon calcitonin entrapped in poly(ether-ester) sustained release systems

Poly(ether-ester)s composed of hydrophilic poly(ethylene glycol)-terephthalate (PEGT) blocks and hydrophobic poly(butylene terephthalate) (PBT) blocks were studied as matrix for the controlled release of calcitonin. Salmon calcitonin loaded PEGT/PBT films were prepared from water-in-oil emulsions. The initial calcitonin release rate could be tailored by the copolymer composition, but incomplete release of calcitonin was observed. FTIR measurements indicated aggregation of calcitonin in the matrix, which was not due to the preparation method of the matrices, but due to the instability of calcitonin in an aqueous environment. Release experiments showed the susceptibility of calcitonin towards the composition of the release medium, in particular to the presence of metal ions. With increasing amount of sodium ions, a decrease in the total amount of released calcitonin was observed due to enhanced aggregation. The calcitonin had to be stabilized in the matrix to prevent aggregation. Incorporation of sodium dodecyl sulphate (SDS) as a stabilizer in PEGT/PBT matrices increased the percentage of calcitonin released, but could not avoid aggregation on a longer term.

Comicellization of Polystyrene-block-Poly(ethylene oxide) with Cationic and Anionic Surfactants in Aqueous Solutions: Indications and Limits

Interaction of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) with cationic and anionic surfactants was studied using light scattering, sedimentation in ultracentrifuge, and 1H NMR. The complex structure of the mixed solution containing hybrid micelles, micellar clusters, and supermicellar aggregates was confirmed by independent experiments. By proton NMR, addition of anionic surfactant, sodium dodecyl sulfate (SDS), to PS-b-PEO solution results in loosening the micelle cores and an increase of the PS molecular mobility in the presence of surfactant. At the same time, incorporation of SDS into the block copolymer solution leads to noticeable broadening of the signals related to methylene protons of the surfactant, which can be assigned to a decrease of mobility of surfactant alkyl chains “immobilized” on the PS cores. These data along with ultracentrifugation of hybrid solutions containing PS-b-PEO and surfactant at various concentrations prove that comicellization occurs and mixed micelles are formed. However, this phenomenon is observed up to a certain limiting concentration of the surfactant. In the case of cetyl pyridinium chloride (CPC), increase of surfactant loading up to 0.05 mol/L results in the solutions containing CPC micelles along with hybrid micellar clusters and supermicellar aggregates.

Interactions among Hydrophobically Modified Polyelectrolytes and Surfactants of the Same Charge

Effects of sodium dodecyl sulfate (SDS) on surface tension and rheology of aqueous solutions of an associative polymer, poly(ethylene oxide)−b-poly(propylene oxide)−b-(poly(ethylene oxide))−g-poly(acrylic acid) (Pluronic-PAA) have been studied. SDS starts to bind to the Pluronic-PAA copolymer at a concentration that is 25-fold lower than the critical micellization concentration (CMC) of the surfactant. The data indicate predominant binding between SDS and polyether segments of Pluronic-PAA. Incorporation of SDS into the Pluronic micelles makes the polymer less surface-active, as the surface tension increases. The Pluronic-PAA chains collapse when SDS binds, because the surfactant enhances hydrophobic intramolecular associations.

Physicochemical aspects of drug release. XVI. The effect of storage on drug dissolution from solid dispersions and the influence of cooling rate and incorporation of surfactant

Solid dispersions of 10% w w griseofulvin were prepared with polyethylene glycol (PEG) 3000 or xylitol as carriers, with or without the incorporation of 2% w w sodium dodecyl sulphate (SDS). The dispersions were cooled either slowly at room temperature or rapidly in liquid nitrogen. The dispersions were stored under controlled conditions at 25, 35 and 45°C and dissolution rate studies, particle size measurements, phase analysis and heat of fusion measurements were performed at intervals during 10 months. In dispersions with PEG as carrier, without SDS, griseofulvin was present in crystalline form. The dissolution rate was unchanged during storage for dispersions prepared with slow cooling, but decreased for dispersions prepared with rapid cooling. This may have been caused by an increase in PEG crystallinity with storage time. With the incorporation of SDS, the dissolution rate initially increased considerably for dispersions with PEG as carrier. Griseofulvin was dissolved in the carrier/ surfactant system in dispersions prepared with slow cooling, whereas griseofulvin was present in pure crystalline form in corresponding dispersions prepared with rapid cooling. Dispersions stored at 45°C liquified on storage independent of cooling procedure and were excluded from the study. The dissolution rate decreased considerably for dispersions prepared with slow cooling, since the dissolution of PEG was impaired by the incorporation of SDS. The dissolution rate of dispersions prepared with rapid cooling also decreased with storage temperature. Griseofulvin was present in crystalline form in all dispersions with xylitol as carrier and the dissolution rate and particle size remained unchanged irrespective of storage temperature and time. The dissolution rate was increased with the incorporation of SDS, but not to the same extent as in PEG dispersions. With increase in storage temperature the dissolution rate decreased, because of decreased dissolution of xylitol with the incorporation of SDS.

Detection of a novel catalase in extracts of Mycobacterium avium and Mycobacterium intracellulare.

A novel class of catalase, which differs from the previously described M- and T-catalases of mycobacteria, was detected in strains of Mycobacterium avium and M. intracellulare. Designated A-catalase, this enzyme resisted inactivation at 68 degrees C, was inactivated by 3-amino-1,2,4-triazole (aminotriazole), and exhibited no peroxidase activity. All of these properties distinguished the enzyme from T-catalase. The A-catalase exhibited a Km of 70 mM H2O2, which is between the upper and lower extremes of the ranges reported for T- and M-catalases, respectively. The A-catalase appeared to be more hydrophobic than M-catalase and did not react with antiserum to a representative sample of this class. The banding patterns of T- and M-catalases seen by polyacrylamide gel electrophoresis (PAGE) were essentially unaffected by the incorporation of sodium dodecyl sulfate (SDS) into the PAGE system, whereas the single band of A-catalase seen by PAGE without SDS resolved into as many as five bands in the presence of SDS; these bands were all of slower mobility than the original band. The banding pattern seen with SDS appeared to be related more to counterion charge effects than to molecular size increases that could be attributed to SDS complexed to the protein. It remains to be determined whether the multiple A-catalase bands reflect different proteins or different SDS micellar complexes of a single protein.

Amino Acid Analysis and Enzymatic Sequence Determination of Peptides by an Improvedo-Phthaldialdehyde Precolumn Labeling Procedure

Abstract Primary amino acids react with o-phthaldialdehyde in the presence of mercaptans to form intensely fluorescent derivatives. By the use of reverse-phase high-performance liquid chromatography, a mixture containing 26 of these derivatives was efficiently resolved with an analysis time of less than 35 minutes. The quantitation of the individual amino acids was reproducible with an average relative deviation of ± 1.4% and had a detection limit of approximately 50 femtomoles. Improvements in the stability and fluorescence response of lysine and hydroxylysine were obtained by the incorporation of sodium dodecyl sulfate in the derivatizing medium. Applications of the chromatography system involving the amino acid analysis of peptides after either acid or enzymatic hydrolysis are presented. Methods for the sequence analysis of picomole quantities of peptides by time course hydrolysis with exopeptidases were also developed, which employed the above separation procedure for the identification and quantifica...

New continuous-flow analysis for simultaneous determination of creatinine and uric acid in 200 microliters of serum without use of a dialyzer.

We present a new method for direct continuous-flow (AutoAnalyzer II) measurement of serum creatinine and uric acid. The manifold is simple, inexpensive, and can be constructed in the laboratory. Only 200 microliters of serum is needed; analysis rate is 60 samples per hour. The incorporation of sodium dodecyl sulfate and the simultaneous provision of blank subtraction make it possible to omit the dialysis step. Our method does not require the linearizer, since instrument response and concentration of creatinine and uric acid are linearly related to 200 and 120 mg/liter, respectively. The percentages of steady state, interaction, and recovery are acceptable, Precision is excellent and the results obtained from the new method correlate well with those obtained by the comparison methods. Interferences are few and, when encountered, are generally smaller than in the modified Technicon method. Marked hemolysis interferes only with the uric acid assay; marked turbidity has no effect on results for creatinine. Icteric serum with total bilirubin of 50 and 100 mg/liter interferes significantly with results for creatinine and uric acid, respectively, by the new method.