Amphiphilic Diblock Copolymer Surface

10 11 Both visible and infrared (IR) spectroscopic ellipsometry have been employed to study the 12 structure of thin layers of bovine submaxillary mucin (BSM) adsorbed on poly(acrylic acid13 block-methyl methacrylate) (PAA-b-PMMA) copolymer and poly(methyl methacrylate) 14 surfaces at three pH values (3, 7 and 10). The adsorbed mucin layer on the copolymer surface 15 had the greatest thickness (17 nm) when adsorbed from a mucin solution at a pH of 3. For the 16 first time, IR ellipsometry was used to identify adhesive interactions and conformational 17 changes in mucin/polymer double layers. After applying the regularized method of 18 deconvolution in the analysis, the formation of hydrogen bonds between the carboxyl groups of 19 the BSM and PAA-b-PMMA copolymer in double layers has been found. The IR ellipsometry 20 data, in agreement with the visible ellipsometry analysis, indicate the pH dependence of 21 adhesion of mucin to the copolymer surface. There is an increase in the amount of hydrogen22 bonded carboxyl groups in mucin deposited at a pH of 3. There is no evidence that the mucin’s 23 amide groups participate in this bonding. At the lower pH, the IR ellipsometry spectra after 24 deconvolution reveal an increase in the proportion of β-sheets in the BSM upon adsorption on 25 the copolymer surface, indicating a more unfolded, aggregated structure. The IR ellipsometry 26 data also indicated some changes in the conformational states of the side groups in the 27 copolymer induced by entanglements and bonding interactions with the mucin 28 macromolecules. Deconvolution provides an unprecedented level of information from the IR 29 ellipsometry spectra and yields important insights. 30 31 Index Headings: IR ellipsometry; IR spectroscopy; Deconvolution; Mucoadhesion; Hydrogen 32 bonding; Mucin 33