Abstract: The interaction of proteins and the interface is a universal but complex phenomenon in nature, which plays an extremely important role in many fields such as physics, biotechnology, chemical engineering, medicine, and environmental science. For example, the structural mutation and dysfunction caused by the misfolding of proteins at the biointerface are directly related to the occurrence and development of various diseases. Precise characterization of the conformations and dynamics of interfacial proteins in situ and in real-time is the core of revealing the function of interfacial proteins, which is of great importance to elucidate the mechanism of neurodegenerative diseases associated with protein aggregation. Nevertheless, there is still a lack of knowledge about their structure and dynamics at this moment. Protein folding is also an unresolved problem in molecule biology central rules. It is mainly because its characterization technology has to require enough structural and temporal resolution as well as requests for in situ, in real-time, in vivo, and non-invasive measurement, yet few methods can meet all the requirements. Sum frequency generation vibrational spectroscopy (SFG-VS) is a powerful technique that can probe the structure and dynamics of interfacial protein molecules at the molecular level. In this review, the application of SFG-VS in the structure and dynamic characterization of interfacial proteins were introduced in details. By probing different protein backbone vibrational bands of amide I, amide III and amide A in situ and in real-time, the precise measurements of the structure, conformation transition and dynamic features of interfacial protein molecules can be achieved, which can further reveal the molecular mechanisms of protein-membrane interaction, protein-protein interaction and protein aggregation. This review will provide a new train of thought for people to study the physical and chemical problems of complex interface systems.

Key words: Interfacial proteins; Sum frequency generation vibrational spectroscopy; Amide bands; Conformations; Structure and dynamics