The precise assignments of cross polarization/magic angle spinning (CP/MAS) (13)C NMR spectra of cellulose I(alpha) and I(beta) were performed by using (13)C labeled cellulose biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 strain from culture medium containing D-[1,3-(13)C]glycerol or D-[2-(13)C]glucose as a carbon source. On the CP/MAS (13)C NMR spectrum of cellulose from D-[1,3-(13)C]glycerol, the introduced (13)C labeling were observed at C1, C3, C4, and C6 of the biosynthesized cellulose. In the case of cellulose biosynthesized from D-[2-(13)C]glucose, the transitions of (13)C labeling to C1, C3, and C5 from C2 were observed. With the quantitative analysis of the (13)C transition ratio and comparing the CP/MAS (13)C NMR spectrum of the Cladophora cellulose with those of the (13)C labeled celluloses, the assignments of the cluster of resonances which belong to C2, C3, and C5 of cellulose, which have not been assigned before, were performed. As a result, all carbons of cellulose I(alpha) and I(beta) except for C1 and C6 of cellulose I(alpha) and C2 of cellulose I(beta) were shown in equal intensity of doublet in the CP/MAS spectrum of the native cellulose, which suggests that two inequivalent glucopyranose residues were contained in the unit cells of both cellulose I(alpha) and I(beta) allomorphs.

Using the two-dimensional (2D) refocused CP-INADEQUATE spectra of natural abundance Cladophora and tunicate celluloses, we determined the 13 C homonuclear through-bond correlations of cellulose IR and Iβ, respectively. Two sets of the 13 C-13 C connectivities from C1 through C6 were observed in the 2D INADEQUATE spectrum of the respective cellulose where two directly bonded carbons share the common frequency in the double quantum dimension, which indicated that both cellulose I R and Iβ contain two magnetically nonequivalent anhydroglucose residues in the unit cells. After the 13 C assignment of each carbon of the cellulose IR and Iβ, assignments of the 1 H chemical shifts of protons attached to each carbon of the both allomorphs were performed by use of the 2D MAS-J-HMQC spectra of the cellulose samples for the first time. These spectra gave the through-bond 13 C-1 H correlations, which allowed the assignment of the 1 H chemical shifts of protons that bind to C1, C3, C4, and C6 of the cellulose IR and Iβ. From the differences in the 13 C and 1 H shifts of cellulose IR and Iβ, it was revealed that the primary difference between two forms of cellulose I was in the conformations of anhydroglucose residues contained in the cellulose chains. In addition, the conformational difference in the torsion angle around the β-1,4 linkage between cellulose I R and Iβ was suggested by the notable differences in their 1 H chemical shifts of protons attached to C1.

Novel hydrogels were prepared from carboxymethyl cellulose (CMC) sodium salt by crosslinking with polyethylene glycol diglycidyl ether (PEGDE). The detailed structures of the hydrogels were determined via FTIR and solid-state NMR spectroscopic analyses. Increasing the feed ratio of PEGDE to CMC in the reaction mixture led to an increase in the crosslinking degree, which enhanced the physical strength of the hydrogels. The hydrogels exhibited enzyme degradability, and after 3 days of incubation with cellulase, 62-28 wt% of the CMC in the hydrogel was degraded under the conditions employed in this study. In addition, the hydrogels exhibited protein adsorption and release abilities, and the amounts of proteins adsorbed on the hydrogels and the release profile of the proteins depended on the protein sizes and crosslinking degree of the hydrogels. These unique properties might enable the use of CMC-based hydrogels as drug delivery system carriers for protein-based drugs if the biological safety of the hydrogel can be verified.

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13C homonuclear through-bond correlations of alpha- and beta-chitin were determined by using two-dimensional (2D) INADEQUATE spectra of these allomorphs purified from crab shell and squid pen, respectively. The 2D (13)C-(13)C correlation spectra where two directly bonded carbons share a common double-quantum frequency (DQ) enabled us to precisely assign all (13)C resonances of the chitin allomorphs for the first time. Following the complete (13)C assignment, (1)H chemical shifts of protons attached to each carbon nuclei were assigned by 2D frequency-switched Lee-Goldberg (FSLG) (1)H-(13)C heteronuclear correlation (HETCOR) spectra of the chitin allomorphs, recorded with a short mixing time (60 micros) to provide isotropic (1)H-(13)C chemical shift correlations between bonded pairs proton and carbon nuclei. From the (13)C and (1)H chemical shifts of chitin allomorphs, all 2-deoxy-2-acetamide-D-glucose (N-acetyl-D-glucosamine) monomer units in each allomorph were revealed to be an identical (13)C-(13)C backbone conformation and magnetically equivalent. In addition, it was strongly suggested that there are two different hydrogen-bonding patterns at the hydroxyl groups of alpha-chitin by comparing (1)H chemical shifts at the C6 site of alpha-chitin with those at the same site of beta-chitin.

Nanofibrillated bacterial cellulose (NFBC) is produced by culturing a cellulose-producing bacterium (Gluconacetobacter intermedius NEDO-01) with rotation or agitation in medium supplemented with carboxymethylcellulose (CMC). Despite a high yield and dispersibility in water, the product immediately aggregates in organic solvents. To broaden its applicability, we prepared amphiphilic NFBC by culturing strain NEDO-01 in medium supplemented with hydroxyethylcellulose or hydroxypropylcellulose instead of CMC. Transmission electron microscopy analysis revealed that the resultant materials (HE-NFBC and HP-NFBC, respectively) comprised relatively uniform fibers with diameters of 33 ± 7 and 42 ± 8 nm, respectively. HP-NFBC was dispersible in polar organic solvents such as methanol, acetone, isopropyl alcohol, acetonitrile, tetrahydrofuran (THF), and dimethylformamide, and was also dispersible in poly(methyl methacrylate) (PMMA) by solvent mixing using THF. HP-NFBC/PMMA composite films were highly transparent and had a higher tensile strength than neat PMMA film. Thus, HP-NFBC has a broad range of applications, including as a filler material.

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