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

Authors :
Zhao-Hua Ren
Yi Liu
Qi-Xiang Mei
Lu Lai
Zhi-Qiang Zhou
Ping Mei
Yan-Cheng Zheng
Source :
Soft Matter. 13:7273-7282
Publication Year :
2017
Publisher :
Royal Society of Chemistry (RSC), 2017.

Abstract

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.

Details

ISSN :
17446848 and 1744683X
Volume :
13
Database :
OpenAIRE
Journal :
Soft Matter
Accession number :
edsair.doi.dedup.....c424f1d4553fe467c9bc5e6ae6a17444
Full Text :
https://doi.org/10.1039/c7sm01607g