Adsorption and Conformation Behavior of Lysozyme on a Gold Surface Determined by QCM-D, MP-SPR, and FTIR.

Paulina Komorek,Barbara Jachimska,Elisha Martin

doi:10.3390/ijms22031322

Abstract

The physicochemical properties of protein layers at the solid–liquid interface are essential in many biological processes. This study aimed to link the structural analysis of adsorbed lysozyme at the water/gold surface at pH 7.5 in a wide range of concentrations. Particular attention was paid to the protein’s structural stability and the hydration of the protein layers formed at the interface. Complementary methods such as multi-parameter surface plasmon resonance (MP-SPR), quartz crystal microbalance with energy dissipation (QCM-D), and infrared spectroscopy (FTIR) were used for this purpose. The MP-SPR and QCM-D studies showed that, during the formation of a monolayer on the gold surface, the molecules’ orientation changes from side-on to end-on. In addition, bilayer formation is observed when adsorbing in the high-volume concentration range >500 ppm. The degree of hydration of the monolayer and bilayer varies depending on the degree of surface coverage. The hydration of the system decreases with filling the layer in both the monolayer and the bilayer. Hydration for the monolayer varies in the range of 50–70%, because the bilayer is much higher than 80%. The degree of hydration of the adsorption layer has a crucial influence on the protein layers’ viscoelastic properties. In general, an increase in the filling of a layer is characterized by a rise in its rigidity. The use of infrared spectroscopy allowed us to determine the changes taking place in the secondary structure of lysozyme due to its interaction with the gold surface. Upon adsorption, the content of II-structures corresponding to β-turn and random lysozyme structures increases, with a simultaneous decrease in the content of the β-sheet. The increase in the range of β-turn in the structure determines the lysozyme structure’s stability and prevents its aggregation.

Highlights

The interaction of proteins with solid surfaces is a crucial phenomenon, influencing many biological and industrial processes
Adsorption of blood proteins on some materials not adapted to biomedical applications can lead to thrombosis [1,2], in the chromatography technique, it provides the opportunity for phases separation [3,4], while in the biotechnological area, it can act as the basis for designing biosensors [5,6,7,8]
Adsorption of Lysozymes on Gold Surface Monitored by Multi-Parametric Surface Plasmon

Summary

Introduction

The interaction of proteins with solid surfaces is a crucial phenomenon, influencing many biological and industrial processes. It should be noted that the properties of the resulting protein layers are crucial for technological reasons This is because all proteins’ functions and activity depend on their biological and chemical parameters, which are directly related to their structure [16,17]. For this reason, multi-faceted characterization of proteins after their adsorption can contribute to the understanding of structure-property relationships, which is so essential in the application area [18,19,20,21,22,23]. The hydration of protein layers is important, but is not well understood This aspect was studied, among other things, by Ouberai et al, who determined the hydration of lysozymes depending on the surface coverage [26].

Objectives

Methods

Conclusion