Fourier transform IR attenuated total reflectance study on the secondary structure of poly(γ ‐methyl L‐glutamate) surfaces treated with formic acid

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Abstract
Fourier transform ir attenuated total reflectance (FTIR ATR) spectra have been obtained to investigate the secondary structure of poly(γ ‐methyl L‐glutamate) (PMLG) surfaces untreated and treated with formic acid in a quantitative manner. Curve analysis including Fourier self‐deconvolution and the band fitting was applied to the ir spectra in the amide II region, revealing that the amide II band of those surfaces consists of five components. The essentially α‐helical form in the PMLG surface layer transformed readily into the β‐structure by the formic acid treatment, and the β‐structure content increased with increasing time of the treatment. The content of random coil structure of treated PMLG was generally very little and/or negligible. The depth profile obtained by considering the depth of ir beam penetration indicated that the β‐structure content also increased with approaching the outermost surface.