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The interaction between biological surfactant sodium deoxycholate (NaDC) and nonionic surfactants polyoxyethylene (n) nonylphenol ether (NPn) for the formation of micelles in aqueous solution were investigated. Surface tension, interfacial dilational viscoelasticity, and transmission electron microscopy (TEM) were characterized to systematically study the interaction between NaDC and NPn in buffer solution. At last, the mechanism of the interaction between NPn and NaDC were analyzed. The surface tension results show that the interaction between NaDC and NPn was displayed synergism action. The composition of the mixed systems has been estimated on account of the regular solution theory, Clint's equation, Rubingh theory and Rosen theory. The surface dilational rheology provided abundant effective information on the feature of adsorbed layers. From the oscillating barrier measurements, the peak values of the dilational modulus moved to lower concentrations in NaDC/NPn binary system compared to single surfactant. The dilational elasticity of the binary system decreased distinctly on the basis of the rigid structure of NaDC. The interaction of these two substances was proved directly by TEM images, that the boundaries of the aggregates are clearer due to the protection of NPn molecules. The new complex systems have potential application in environmental protection. Schematic illustration of the aggregation in NPn/NaDC mixed systems and concentration increased from left to right. [ABSTRACT FROM AUTHOR]

Two pairwise genetic interactions (B cell lymphocyte kinase(BLK) rs13277113,B cell scaffold protein with ankyrin repeats 1(BANK1) rs3733197andBLKrs13277113membrane metalloendopeptidase like 1(MMEL1)/tumor necrosis factor receptor superfamily member 14(TNFRSF14) rs3890745) have been demonstrated in determining susceptibility to rheumatoid arthritis (RA) without replication, thus this study was performed to examine whether abovementioned genetic polymorphisms were associated with RA and further tests were performed to see whether aforementioned genetic interactions existed in RA among Chinese population. A total of 328 patients with RA and 449 healthy control subjects were included in the current study. The polymorphisms were genotyped using the ligase detection reaction-polymerase chain reaction (LDR-PCR) technology. The association of RA with each polymorphism was analyzed by multivariate logistic regression model. Interaction analysis was done by multiple methods. Significant difference in genotype distribution ofBLKrs13277113 polymorphism between RA patients and healthy controls was found (p = 1.01 × 10−2). The major allele A ofBLKrs13277113 polymorphism was significantly increased in RA patients compared with controls (OR = 1.36, 95% CI = 1.08–1.71,p = 9.27 × 10−3). Significant association of RA with the major allele A ofBLKrs13277113 polymorphism under dominant model was also detected (OR = 2.74, 95% CI = 1.42–5.29,p = 2.73 × 10−3). However, we did not find significant association between neitherBANK1rs3733197 polymorphism norMMEL1/TNFRSF14rs3890745 polymorphism and RA. Non-significant evidence was found for neither additive nor multiplicative interaction for these two pairwise genetic polymorphisms (BLKrs13277113-BANK1rs3733197;BLKrs13277113-MMEL1/TNFRSF14rs3890745). Significant association of RA with G allele ofBANK1rs3733197 polymorphism was only found among individuals carrying A/A genotype of theBLKrs13277113 polymorphism (OR = 1.49, 95% CI = 1.01–2.18,p = .04). In summary, our results indicated that theBLKrs13277113 polymorphism was involved in the genetic background of RA in Chinese population and the association ofBANK1rs3733197 polymorphism with RA was dependent on the genotype ofBLKrs13277113 polymorphism, highlighting B-cell response implicated in the pathogenesis of RA. [ABSTRACT FROM AUTHOR]

Surface tension, fluorescence and circular dichroism (CD) methods have been used to investigate the interaction between a biological surfactant sodium deoxycholate (NaDC) and proteins including bovine serum albumin (BSA) and gelatin. It can be seen from the surface tension measurements that both NaDC/BSA and NaDC/gelatin systems can form complexes and the ability of NaDC/BSA to lower surface tension is more obvious than that of NaDC/gelatin. The formation of the complexes influences not only the polarity of the microenvironment of the systems but also their fluorescence spectra. The far-UV CD spectra shows that the α-helical network of BSA increases first and then decreases as the concentration of NaDC increases, while the random coil content of gelatin always increases. A model of interaction between protein and NaDC influenced by the concentration of NaDC has been brought out based on the data gained from this study. [ABSTRACT FROM AUTHOR]

The effect of NaBr on the interaction between alkyltrimethylammonium bromide (CnTAB (n = 14 for TTAB and 16 for CTAB)) and ss-CD was studied by surface tension method. The first decrease in the γcmc of TTAB/ss-CD in the presence of NaBr mainly due to the elongated effective chain length of the hydrophobic part of the TTAB/ss-CD complexes; while the increase in the γcmc of both of the TTAB/ss-CD and CTAB/ss-CD in the presence of NaBr could be attributed to the close pack of CnTAB at the air/water interface. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between a star-like block copolymer (AP432) and an anionic surfactant sodium oleate (C17H33COONa) was investigated in detail both at the air/water interface and in bulk aqueous solutions. The results of surface tension show that AP432 and C17H33COONa could form mixed micelles. The results obtained from the oscillating barrier measurements at low dilational frequencies (0.01–0.1Hz) reveal that the maximum values of the dilational modulus for AP432/C17H33COONa mixed system moved to lower concentrations compared to those of single AP432 or C17H33COONa aqueous solutions. Steady-state fluorescence measurements indicate that after mixing, the I 1/I 3 values of AP432/C17H33COONa system above the cmc are higher than those of single AP432 or C17H33COONa solutions. This is probably due to a looser pack of the molecules within micelles for the AP432/C17H33COONa mixture, which is also consistent with the results obtained from TEM observations. For comparison, the interaction between a commercially available linear PEO–PPO–PEO copolymer (Pluronics L64) and C17H33COONa was also studied. All experimental results give clear evidence that the interaction between L64 and C17H33COONa is different from that between AP432 and C17H33COONa. [Copyright &y& Elsevier]

Abstract: The interaction between 4-chloro-(2′-hydroxylphenylazo)rhodanine (ClHPAR) and cationic surfactant cetyltrimethyl ammonium bromide (CTAB) was investigated by surface tension, absorption spectra, resonance light scattering (RLS) spectra and transmission electron microscopy. It can be concluded from the experimental results that the hydrophobic forces cannot be neglected, even though the electrostatic interaction between ClHPAR and CTAB plays an important role. The RLS spectral behavior of ClHPAR changes in the presence of CTAB. The efficiency and the effectiveness of ClHPAR–CTAB mixture to decrease the surface tension of water are higher than those of any single component, i.e. CTAB and ClHPAR. As one might expect, NaCl and urine have different effects on the interaction between ClHPAR and CTAB and their interaction also depends on pH. [Copyright &y& Elsevier]