Infrared study of molecular aggregation in the poly(.alpha.-benzyl L-glutamate)/benzyl alcohol system

The microfibrillar network in gels of poly(γ-benzyl-L-glutamate) in benzyl alcohol

“…A microfibrillar network exhibiting a wide variation in the thickness of the microfibrils, as seen in a TEM image of a freeze-fracture replica, was previous rep~r t e d .~ A recent investigation by infrared spectroscopy indicated also that the melting of PBLG gels is a multistage process in which larger fibrils are a t first broken up. 56 It has been realized for many years that the complex microstructure of PBLG gels is related to the kinetics of the gelation process. This report describes the gelation and melting behavior of isotropic solutions of PBLG of a relatively low molecular weight (86,000), at slow cooling and heating rates.…”

Pursuit of perfection: three‐dimensional ct angiographic “objective quantification” of aortic valve structures for transcatheter aortic valve implantation

“…Amide I and II vibrational modes are highly sensitive to the global conformation of polypeptides (e.g., α‐helix, β‐sheet, or random coil). 62 FTIR analysis reveals that the SWCNT‐attached PBLGs adopt random‐coil conformations for the entire MW range (7.5–21.1 kg·mol −1 ), as evidenced by the amide I and II bands at 1674 and 1529 cm −1 respectively, 63, 64 whereas free PBLGs exhibit two bands at 1651 and 1545 cm −1 that are characteristics of α‐helical conformations. 65 This suggests that interactions between SWCNTs and PBLGs induce the unraveling of PBLG α‐helices into coil conformations.…”

“…Poly(γ‐benzyl‐ L ‐glutamate)s (PBLGs) are biocompatible polypeptides that adopt α‐helical conformations with a persistent chain length ( l p ) of 1500 Å in selected solvents. 30 They are known to aggregate in dilute solutions of helicogenically poor solvents (e.g., benzene, toluene, and benzyl alcohol) 31, 32 and form thermoreversible gels above a critical concentration. 33, 34 PBLG gels have been shown to consist of fibrillar networks with fibril diameters ranging from tens to hundreds of nanometers.…”

Thermoreversible gelation of helical polypeptide/single‐walled carbon nanotubes and their solid‐state structures

“…Amide I and II vibrational modes are highly sensitive to the global conformation of polypeptides (e.g., a-helix, b-sheet, or random coil). 62 FTIR analysis reveals that the SWCNTattached PBLGs adopt random-coil conformations for the entire MW range (7.5-21.1 kgÁmol À1 ), as evidenced by the amide I and II bands at 1674 and 1529 cm À1 respectively, 63,64 whereas free PBLGs exhibit two bands at 1651 and 1545 cm À1 that are characteristics of a-helical conformations. 65 This suggests that interactions between SWCNTs and PBLGs induce the unraveling of PBLG a-helices into coil conformations.…”