Impact of multiple quaternary ammonium salts on dynamic properties of BSA adsorption layer at different pH values.

The interaction mechanism of multiple quaternary ammonium salts (MQAS) with bovine serum albumin (BSA) was examined by the fluorescence quenching method and circular dichroism (CD) spectra. Moreover, the effects of MQAS on the dynamic properties of BSA adsorption layers at different pH values were investigated using dilational interfacial rheology. Results show that the quenching constants increase with an increase in pH values and decrease with an increase in the experiment temperature at pH 5.3. The quenching mechanism is static quenching, and the electrostatic force dominates the interaction between MQAS and BSA at pH 5.3. Due to three positive head groups, MQAS can significantly affect the dynamic interfacial activity of BSA molecules at a relatively low concentration. At pH 4.3, the electrostatic repulsion is unfavorable for the formation of MQAS/BSA complexes. Consequently, MQAS molecules will replace BSA molecules from the interface by competitive adsorption. At the pH value above the isoelectric point of BSA, the electrostatic attraction is better for the formation of MQAS/BSA complexes, which exhibit a rapid adsorption rate and an enhanced interfacial activity. Moreover, the kinetic dependencies of interfacial dilational elasticity for the MQAS/BSA mixtures become nonmonotonous. The appearance of the maximum interfacial elasticity values can be attributed to the formation of tails and loops, which suggests that the addition of MQAS destroys the secondary and tertiary structure of protein in the bulk phase. In addition, the effects of MQAS on the secondary structure of protein were demonstrated by CD spectra.

[Study on quantitative mechanism and the interference of the UV spectrum of HABS reduced by ß-Cyclodextrin].

A novel ultraviolet absorption spectrometry method was developed for the quantitative determination of HABS by adding ß-cyclodextrin with the molar ratio of 1:1 in strong interference aqueous solution. The results indicated that the effect of several common interfering flooding agents (SAS, OP-10, HPAM) on the determination of HABS could be greatly reduced in ß- cyclodextrin aqueous solution. Thus, the determination errors of the determined HABS were less than 2.0% under strong inter- ference, and the detection limit (S/N==3) of the method could be also as high was 8.3-9.1 x 10(-4) mg · L(-1). Various characterization results including 1H-NMR, TG-DSC and FTIR showed the interaction between ß-cyclodextrin and HABS. The results of H-NMR analysis showed that HABS molecule could enter into the interior of the cavity of ß-cyclodextrin molecule. TG-DSC analysis exhibited that the stable inclusion of ß-cyclodextrin and HABS could be automatically formed. The interactions between the functional groups of ß-cyclodextrin and HABS were showed by FTIR analysis, which also exhibited that the stable inclusion could be formed by HABS entering from the narrow or the broad mouth of the ß-cyclodextrin. The interference of the UV spectrum of HABS could be reduced by ß-cyclodextrin since the interaction between ß-cyclodextrin due to the interaction between ß-cyclodextrin and HABS in the inclusion complex.

[Study on the enhanced spectrum quantitative analysis of SDBS induced by beta-cyclodextrin].

A novel enhanced ultraviolet absorption spectrometry method was developed for the quantitative analysis of SDBS induced by beta-cyclodextrin(beta-CD) with strong interferences. The ultraviolet absorption spectra of SDBS indicated that the presence of beta-CD could result in the enhancement of absorption intensities of SDBS. A good linearity was obtained between the UV-absorption intensity of the system and the concentration of SDBS. The results indicated that the determination precision and the determination ranges of SDBS could be greatly improved by beta-CD. The effect of several common interfering substances (SDS, OP-10, HPAM) on the determination of SDBS could be significantly reduced in beta-CD aqueous solution. Therefore, the maximum errors of the determined SDBS were less than 2.0% under multifactor interferences, and the precision of the method was also as high as 10(-2) - 10(-3) mg x L(-1). The stable inclusion of beta-CD and SDBS could be automatically formed in water with molar ratio of 1 : 1. The stability constant of the inclusion, K(a), was 87 and the standard Gibbs function of molar reaction, delta(gamma)G(m)(see symbol) (298 K), was -11.064 kJ x mol(-1). FTIR analysis exhibited that SDBS could be induced by beta-CD since the phenyl group in SDBS molecule could exist stably in the cavity of beta-CD and form the inclusion.

HSP70/CD80 DNA vaccine inhibits airway remodeling by regulating the transcription factors T-bet and GATA-3 in a murine model of chronic asthma.

INTRODUCTION: Airway remodeling is an important pathologic feature of chronic asthma. T-bet and GATA-3, the key transcription factors for differentiation toward Th1 and Th2 cells, play an important role in the pathogenesis of airway inflammation, airway hyperresponsiveness and airway remodeling. Previous studies showed that HSP70/CD80 DNA vaccine can reduce airway hyperresponsiveness and airway inflammation in acute asthmatic mice. The present study was designed to determine the effect of HSP70/CD80 DNA vaccine on airway remodeling through regulating the development of Th1/Th2. MATERIAL AND METHODS: Before being sensitized and challenged by ovalbumin, the BALB/c mice were immunized with DNA vaccine. Lung tissues were assessed by histological examinations. Interferon-γ (IFN-γ)/interleukin-4 (IL-4) levels in bronchoalveolar lavage fluid were determined by ELISA and expressions of IFN-γ, IL-4, T-bet and GATA-3 in spleen were evaluated by real-time polymerase chain reaction. RESULTS: Chronic asthmatic mice had higher airway hyperresponsiveness, a thicker airway wall, more PAS-positive goblet cells, more subepithelial extracellular matrix deposition and more proliferating airway smooth muscle (ASM)-like cells than control mice (p < 0.05). Compared with the chronic asthmatic mice, the treatment with HSP70/CD80 DNA vaccine could reduce airway hyperreactivity, mucus secretion, subepithelial collagen deposition, and smooth muscle cell proliferation (p < 0.05). DNA vaccination also increased levels of IFN-γ/IL-4 in BAL fluid (p < 0.05), and expression of T-bet/GATA-3 in the spleen (p < 0.05). CONCLUSIONS: HSP70/CD80 DNA vaccine can inhibit airway remodeling through regulating the development of Th1/Th2 subsets in asthmatic mice.