title: Using the FT-IR linear dichroism method for molecular order determination of tendon collagen bundles and nylon 6.
abstract: Polarized Fourier transform-infrared (FT-IR) was used to compare the orientation of vibrational chemical groups of bovine tendon collagen bundles (CBs) to that of nylon 6, a simpler polyamide model, in terms of linear dichroism (LD). Subtraction of spectral profiles identified the most significant differences regarding the amide regions. At 1630cm(-1), the CBs displayed higher peak areas and absorbance when positioned perpendicularly (A⊥) to the plane of polarized light, in comparison with nylon 6. In contrast, at the 1526cm(-1) amide II spectral region the inverse occurred. In the amide III region (1232cm(-1)), the LD was positive and higher for CBs. Dichroic ratios (DR=A||/A⊥) calculated from the average of ten measured spectra for CBs and nylon 6 revealed that the values for CBs were <1.0 in the 3298-1655cm(-1) wavenumber range and >1.0 in the 1536-1234cm(-1) wavenumber range. From 1535 to 1120cm(-1), nylon 6 displayed DR values higher than those of CBs. The LD band integrated areas were higher in CBs than in nylon 6. The LD differences between CBs and nylon 6 are probably due to a more complex chemical composition and supramolecular oriented architecture in CBs in comparison to nylon 6.
authors.affiliation: Department of Structural and Functional Biology, Institute of Biology, University of Campinas (Unicamp), Rua Monteiro Lobato 255, CEP 013083-862 Campinas (SP), Brazil. Electronic address: camposvi@unicamp.br.
authors.forename: Benedicto de Campos
authors.initials: Bde C
authors.lastname: Vidal
mesh_terms: D000818:Animals; D016880:Anisotropy; D040761:Biomimetic Materials / Q000737:chemistry*; D002209:Caprolactam / Q000031:analogs & derivatives* / Q000737:chemistry; D002417:Cattle; D003094:Collagen / Q000302:isolation & purification / Q000648:ultrastructure*; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013710:Tendons / Q000737:chemistry*
chemical_list: D011108:Polymers; C009916:nylon 6; D002209:Caprolactam; D003094:Collagen
keywords: Collagen bundles; FT-IR; Linear dichroism; Nylon 6; Tendons