CIRCULAR DICHROISM SPECTROSCOPY IN THE STUDY OF PROTEIN FILMS

The immobilization of proteins on solid surfaces is a widely adopted strategy in circular dichroism (CD) studies. This approach enables the investigation of protein secondary structures and the observation of conformational changes under conditions that closely resemble the biological environment and/or environments with reduced water content. An additional advantage is the mitigation of solvent scattering and absorption effects. In this work, we have employed CD spectroscopy to investigate the structure of antigenic proteins deposited onto quartz plates in the form of semi-dehydrated films. Our main goal was exploring and correlating their spectral features with those of proteins incorporated into mesoporous silica particles. Protein immobilization onto solid surfaces was achieved using various methods—including physical adsorption, covalent bonding, or specific ligand-mediated interactions— depending on the nature of the protein and the surface. The films were analyzed using both conventional spectropolarimeters and synchrotron radiation CD spectroscopy. Efficient deposition of a globular protein demonstrated the preservation of characteristic spectral bands associated with the native protein conformation, suggesting retention of its biological activity and native folding. These are critical factors for proper protein functionality.