Preparation and characterization of highly oriented poly(γ‐benzylL‐glutamate) networks and gels with long channels with micrometer‐scale diameters

Abstract

Poly(␥-benzyl l-glutamate) (PBLG) gels with highly oriented ␣-helix chains were prepared by the crosslinking of PBLG chains through changes in the concentration of ethylenediamine, used as a crosslinker, in 1,4-dioxane in the presence of the strong magnetic field of an NMR magnet with a strength of 10.5 T. The experimental results showed that in one of these gels, long channels with an average diameter of about 100 m were formed by phase separation between crosslinked PBLG and the solvent. Furthermore, three-dimensional 1 H-NMR imaging patterns showed that the long channels were aligned in the direction parallel to the ␣-helix axis. The PBLG gel was swollen in the direction perpendicular to the ␣-helix axis, but it was not swollen in the direction parallel to the ␣-helix axis. The X-ray diffraction patterns of the gel showed that the interchain distance between the two nearest neighboring PBLG chains changed from 13.4 to 18.1 Å with a change in the swelling degree.

Fibrillar gels via the self-assembly of poly(l-glutamate)-based statistical copolymers

“…BLG ratios (at least 24 : 76) prevent gelation entirely; however, the fact that P(BLG 0.89 -co-DLAG 0.11 ) 53 was able to gel shows that sufficiently low DLAG to BLG ratios (less than 24 : 76 and at least up to 11 : 89) does not prevent physical gelation. We also found that for similar LAG to BLG ratios, the α-helical contribution increases with increasing chain length.…”

“…Despite the harsh debenzylation conditions, the gels showed no collapse and maintained their overall shape and volume. ) showing an intense peak at 6-7°and a less intense peak at 17°(resolved by Levenberg-Marquardt curve-fitting); the amorphous halo is centered around 20-21°; (a) PBLG 51 , (b) P(BLG 0.76 -co-DLAG 0.24 ) 59 , (c) P(BLG 0.77 -co-LAG 0.23 ) 57 , (d) P(BLG 0.89 -co-DLAG 0.11 ) 53 . This indicates that the porous microstructure observed in the organogel was preserved, as confirmed by SEM (Fig.…”

“…25,26 The highly concentrated solutions used (25 wt%) typically led to dense gels with low porosity and swelling, 18 and the crosslinking treatment, which reacted multifunctional amines with benzyl ester side groups, was extremely time-consuming (>3 days) and lacked of control over the position and number of crosslinks. 18,19,53 In order to overcome these obstacles and achieve biocompatible fibrillar networks, we have developed a novel organogelto-hydrogel route to prepare highly absorbent, porous, and stimuli-responsive PLGA/PLG hydrogels. This was accomplished by the synthesis by NCA ROP of statistical copolymers 54 of BLG and allylglycine (AG) of relatively low molar masses (i.e., down to 11 kDa), and their photo-crosslinking gelation followed by the deprotection of the carboxylic acid moieties.…”

Preparation of poly(γ-benzyl-L-glutamate) nanofibers by electrospinning from isotropic and biphasic liquid crystal solutions

“…These separations are attributed to the hexagonal lattice of the closed-packed structure of the rod-like a-helices: 11,18 the former separation is the longitudinal periodicity of the a-helices, and the latter one is similar to the reported transversal lattice constant of the hexagonal closed-packed structure of the a-helices. 9,11,29,30 The WAXD pattern for the nanofiber from the isotropic solution (D¼0.65 mm, Figure 7b) exhibited peaks slightly concentrated on the pole and the equator, which suggests a uniaxial orientation of a small fraction of the hexagonal lattice, whereas the pattern for the thicker aligned fiber electrospun from the isotropic solution (D¼1.35 mm) exhibited Debye-Scherrer rings (Supplementary Figure S1). This improvement in the orientation is consistent with the fiberdiameter dependence of Dn.…”