In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

• Published in: ACS applied materials & interfaces Vol. 7; no. 23; pp. 12430 - 12439
• Main Authors: Kroning, Annika, Furchner, Andreas, Aulich, Dennis, Bittrich, Eva, Rauch, Sebastian, Uhlmann, Petra, Eichhorn, Klaus-Jochen, Seeber, Michael, Luzinov, Igor, Kilbey, S. Michael, Lokitz, Bradley S, Minko, Sergiy, Hinrichs, Karsten
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 17.06.2015; American Chemical Society (ACS)
• Subjects: Acrylic Resins - chemistry; Adsorption; BASIC BIOLOGICAL SCIENCES; in situ infrared ellipsometry; infrared spectroscopy; MATERIALS SCIENCE; Nanostructures - chemistry; polymer brushes; protein adsorption; Proteins - analysis; Proteins - chemistry; Proteins - metabolism; solid−liquid interface; Spectrophotometry, Infrared - methods; stimuli-responsive; protein adsorption; solid−liquid interface; in situ infrared ellipsometry; stimuli-responsive; polymer brushes; infrared spectroscopy
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am5075997

The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes containing poly­(N-isopropylacrylamide) and poly­(acrylic acid) with high potential for biosensing and biomedical applications are studied by in situ infrared-spectroscopic ellipsometry (IRSE). IRSE is a highly sensitive nondestructive technique that allows protein adsorption on polymer brushes to be investigated in an aqueous environment as external stimuli, such as temperature and pH, are varied. These changes are relevant to conditions for regulation of protein adsorption and desorption for biotechnology, biocatalysis, and bioanalytical applications. Here brushes are used as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. The important finding of this work is that IRSE in the in situ experiments in protein solutions can distinguish between contributions of polymer brushes and proteins. The vibrational bands of the polymers provide insights into the hydration state of the brushes, whereas the protein-specific amide bands are related to changes of the protein secondary structure.