Influence Of Surfactant Sodium Dodecyl Sulfate Research Articles

SDS‐induced amyloid fibrillation of acidic fibroblast growth factor

Fibroblast growth factors and their receptors regulate a broad range of biological functions from developmental processes during embryogenesis to various physiological roles in the adult state, including regulation of angiogenesis, wound healing, and metabolism. hFGF‐1 also plays a key role in neuroprotection against neurotoxicity in Alzheimer’s disease (AD). The anionic surfactant sodium dodecyl sulfate (SDS) is widely used as a model for induction of amyloid‐like fibrils. In this context, we examined the effects of SDS on FGF1 using a variety of biophysical techniques including, Transmission Electron Microscopy (TEM). The secondary structure of hFGF1 was monitored by incubating hFGF1 with different concentrations of SDS utilizing the far‐UV CD (190‐250 nm) spectroscopy. We found that from 0.08‐0.15mM concentration of SDS, the negative peak at ~206 shifted gradually towards ~212nm while at 0.2mM concentration, far‐UV CD spectra of hFGF‐1 exhibit significant changes with striking shifting of negative peak ~212 nm to ~218 nm and disappearance of positive band at ~228nm which signifies substantial loss of native β‐barrel structure. The aggregation of hFGF‐1 is detected systematically by observing the absorbance at 350nm. The results indicate that at 0.2mM SDS, hFGF1 highly aggregates. In addition to far‐UV CD spectra and turbidity measurement, the influence of SDS on the tertiary structural changes of hFGF1 was studied by mentoring the intrinsic fluorescence of hFGF1 incubated with various concentrations of SDS. The study reveals that 0.2mM SDS is the concentration that affect mostly on the tertiary structure of hFGF1 because of the highest ratio of 305 to 350 at this concentration. Thioflavin‐T (ThT) assay for quantification of Amyloid‐like fibril formation was used to investigate the concentration of SDS that induce maximum hfGF1 fibrils. This study showed that 0.2mM SDS is the concentration that induced the optimum formation of fibrils hFGF1. Based on the results of these experiments, we wanted to do more investigation to achieve more evidence about the effect of SDS on the fibrils hFGF1. Therefore, morphological study by TEM was employed to examine the effect of 0.2mM SDS and 0.6mM SDS on the formation of fibrils hFGF1. At incubation for 1‐hour fibrillar aggregates of hFGF‐1 with average diameter at about 20‐25nm is observed in presence of 0.2mM SDS. All the previous results using biophysical techniques indicate that SDS induces formation of fibrils hFGF1 concentration which assist to better understanding about the causative of the fibrils hFGF1 which lead to find a remedy for the disease related with it.

Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate.

Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS) on the adsorption of the siderophores DFOB (cationic) and DFOD (neutral) and the ligand EDTA (anionic) onto goethite (α-FeOOH) at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III)-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.

Influence of SDS and two anionic hydrotropes on the micellized state of the triblock copolymer E 71G 7E 71

Complex formation between the triblock copolymer E 71G 7E 71, where E denotes ethylene oxide, the central hydrophobic block, phenyl glycidyl ether, is denoted as G, and the subscripts denote the block length, the surfactant sodium dodecyl sulfate (SDS), and the penicillins cloxacillin and dicloxacillin, which can be considered as hydrotropes has been investigated by dynamic light scattering (DLS) and isothermal titration calorimetry (ITC). The different copolymer/amphiphile systems have been studied at a constant copolymer concentration of 10 g dm −3 and at different amphiphile concentrations. For all systems, the relaxation time distributions show a well-defined single mode with a shift toward slightly faster times, which indicates that the electrostatic interactions between the complexes is minimum, and so it is possible to estimate a size in terms of the apparent hydrodynamic radii. For ITC the amphiphile solutions were titrated in two different forms: as monomers (below the cmc) and as aggregates. The data indicate that the interaction between the surfactant and the hydrotropes with the copolymer occurs even at the lowest SDS concentration measured.