Interfacial Interactions of Pectin with Bovine Serum Albumin Studied by Quartz Crystal Microbalance with Dissipation Monitoring: Effect of Ionic Strength

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• 作者：Xiaoyong Wang ; Chada Ruengruglikit ; Yu-Wen Wang ; Qingrong Huang
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2007
• 出版时间：December 12, 2007
• 年：2007
• 卷：55
• 期：25
• 页码：10425 - 10431
• 全文大小：177K
• 年卷期：v.55,no.25(December 12, 2007)
• ISSN：1520-5118

文摘

The effect of ionic strength (I) on the interfacial interactions between pectin and the bovine serum albumin (BSA) surface has been investigated using the quartz crystal microbalance with dissipation monitoring (QCM-D). As I increases from 0.01 to 0.02 M, the frequency shift (ΔF) decreases, whereas the energy dissipation shift (ΔD) changes toward a higher value. Further increase of I from 0.02 to 0.5 M causes both ΔF and ΔD to gradually return to almost zero. The adsorbed mass and thickness of the pectin adlayer estimated from the Voigt model confirm that the adsorption of pectin and the formation of thicker pectin adlayers on a BSA surface are favored by the increase of ionic strength at I = 0.01 ~ 0.02 M. An increase of I above 0.02 M hinders pectin adsorption and causes the formation of a thinner pectin adlayer. The ionic strength-enhanced effect at I values lower than 0.02 M is explained as an increase of ionic strength that can screen the electrostatic repulsion to a larger extent than the electrostatic attraction between pectin and BSA. However, when I is higher than 0.02 M, both electrostatic repulsion and attraction can be significantly screened by the increasing ionic strength, resulting in the ionic strength-reduced effect. On the other hand, the high viscoelasticity of the pectin adlayer revealed by the Voigt model suggests the formation of a network-structured pectin adlayer on the BSA surface, which contains two steps for higher pectin adsorptions at I = 0.0125 ~ 0.1 M by the indication of two slopes in ΔD–ΔF plots.