A comprehensive study of protein–mesoporous–macroporous silica interactions by extended canonical variate analysis of Raman spectra

• Published in: Journal of Raman spectroscopy Vol. 51; no. 2; pp. 335 - 345
• Main Authors: Videira‐Quintela, Diogo, Prazeres, Sofia F., Ortega‐Ojeda, F. E., Montalvo‐García, G.
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.02.2020
• Subjects: Amino acids; Denaturation; Enlargement; extended canonical variate analysis; Galactosidase; Inspection; meso‐macroporous silica; protein; Protein structure; Proteins; Raman spectra; Raman spectroscopy; Silica; Silicon dioxide; Spectrum analysis; support interactions; β-Galactosidase
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.5773

Understanding the protein–support interactions is of major importance when manufacturing bionanomaterials to a certain application. These interactions can be the cause for enhanced properties or denaturation phenomena in the target protein. Raman spectroscopy was applied to a bionanomaterial comprehending the protein β‐galactosidase immobilized by physical adsorption into a mesoporous–macroporous silica material, with a nanoporous network consisting of 9‐nm mesopores and 200‐nm macropores. Raman spectra of the bionanomaterial evidenced a complex amount of differences related to the Raman shifts, intensities, band enlargement, appearance of new bands, and overlapping, in comparison with the silica support and the protein spectra. To help in the analysis of the Raman spectra and in the inspection of possible protein–support interactions, ECVA (extended canonical variate analysis) was used as a chemometric complementary tool, dividing the spectra into four segments: 1 (3,100 to 2,800 cm−1), 2 (1,800 to 1,500 cm−1), 3 (1,500 to 1,200 cm−1), and 4 (1,200 to 900 cm−1). Major alterations in the Amide I band (1,800 to 1,500 cm−1) and the amino acid band regions demonstrated possible structure alterations to a non‐native form of the protein β‐galactosidase. Also, other minor alterations were observed in other spectral regions (3,100 to 2,800 cm−1,1,500 to 1,200 cm−1, and 1,200 to 900 cm−1) also representative of protein structure alteration due to protein–support interactions. The study of protein–support interactions is imperative in the manufacturing of bionanomaterials. Raman spectroscopy combined with the chemometric tool, extended canonical variate analysis, helped in the recognition of Raman band regions associated with structural changes or adjustments of the protein when in contact with the studied support, and the existence of possible interactions are verified in the β‐galactosidase due to alteration in the Amide I and amino acid band regions.