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The α-chitin nanofibril is an alternative to nanocellulose as a building-block for strong films and other nanomaterials. The hypothesis of high film strength for films based on mildly treated insect cuticles was tested. Fibrils from the cuticle of Ruspolia differens (a long-horned bush cricket grasshopper locally known as senene) are disintegrated by a mild process, subsequently characterized by transmission electron microscopy, NMR, Fourier transform infrared spectroscopy, and XRD, and used to prepare strong and transparent films. A mild process (with 20% NaOH treatment for 2 weeks and at room temperature) was used to largely remove the strongly bound protein associated with chitin. The purpose was to reduce chitin degradation. The native structure of chitin was indeed well preserved and close to the native state, as is supported by data for degree of acetylation, molar mass, crystallinity, and crystallite dimensions. The diameter of the smallest chitin fibrils was as small as 3-7 nm (average 6 nm) with lengths larger than or around 1 μm. A stable and well-dispersed colloidal chitin fibril suspension in water was achieved. A nanostructured chitin film prepared by filtration showed high optical transmittance (∼90%) and very high tensile strength (220 MPa). The high tensile strength was attributed to the well-preserved chitin structure, high intrinsic fibril strength, and high colloidal stability of the fibril suspension. Strong, transparent insect chitin films offer interesting alternatives to nanocellulose films because of different resource origins, surface chemistries, and potential antimicrobial properties., QC 20200409

Chitin nanofibers of unique structure and properties can be obtained from crustacean and fishery waste. These chitin nanofibers have roughly 4nm diameters, aspect ratios between 25-250, a high degree of acetylation and preserved crystallinity, and can be potentially applied in hydrogels. Hydrogels with a chitin nanofiber content of 0.4, 0.6, 0.8, 1.0, 2.0, and 3.0wt% were successfully prepared. The methodology for preparation is new, environmentally friendly, and simple as gelation is induced by neutralization of the charged colloidal mixture, inducing precipitation and secondary bond interaction between nanofibers. Pore structure and pore size distributions of corresponding aerogels are characterized using auto-porosimetry, revealing a substantial fraction of nanoscale pores. To the best of our knowledge, the values for storage (13kPa at 3wt%) and compression modulus (309kPa at 2wt%) are the highest reported for chitin nanofibers hydrogels., QC 20160601

The ultimate goal of tissue engineering is to address the current organ shortage problem, i.e. development of an alternative therapeutic strategy to autografting and allografting. Several approaches are currently been used to regenerate damaged tissue using the principles of tissue engineering. Among these, scaffold based tissue engineering wherein, biomaterials are used alone or in combination with cells and biologically active molecules is one of the most attractive and extensively investigated approaches. One of the most important challenges is to ensure proper in vivo performance of the engineered cell-scaffold constructs under challenging microenvironmental conditions of inflammation characteristic of damaged tissues. This calls for the development of cell instructive regenerative biomaterial structures that can communicate with host cells via multiple regulatory signals. The present research project aims to investigate the ability of an injectable matrix from a biodegradable polymer Chitosan' in modulating the host tissue microenvironment to promote regeneration. The overall objective of this study is to develop strategies to improve regeneration of critical size bone defects by creating an optimized inductive microenvironment using an injectable chitosan carrier with cells and rhBMP-2 alone or in combination. The report discusses the studies we performed over the past one year towards evaluating injectable compositions from chitosans of different degree of acetylations in vitro using mouse macrophages and in vivo using mouse calvarial and segmental bone defect model.

NR 20140805

In the present thesis, capillary zone electrophoresis (CZE),matrix-assisted laser desorption/ionization time-of-flight massspectroscopy (MALDI-MS) and size-exclusion chromatography incombination with off-line MALDI-MS (SEC/MALDI-MS) have beenapplied successfully to the analysis of wood and pulpcomponents. The carbohydrate compositions of pulp and holocellulosesamples, as well as of isolated hemicellulose preparations,were determined employing enzymatic hydrolysis and subsequentanalysis of the saccharides released by CZE. SEC/MALDI-MS was employed to characterize the molar massesand molar mass distributions of isolated hemicelluloses andlignins. The samples were first separated using SEC intofractions each containing components exhibiting a narrow rangeof molar masses and the average molar mass of each suchfraction subsequently determined by MALDI-MS. The molar massparameters for the samples were thencalculated on the basis ofthe SEC distribution curves and MALDI-MS spectra. The distribution of 4-O-methylglucuronic acid residues along thepolysaccharide chains of xylans isolated from various woodspecies was examined employing MALDI-MS analysis of theoligosaccharide mixtures obtained by partial acid hydrolysis.In the case of all softwood xylans examined, the major portionof these residues were distributed regularly along the polymer;whereas the 4-O-methylglucuronic acid residues in the hardwood xylansexamined were found to be distributed irregularly. Furthersupport for these experimental findings was obtained bycomputer-assisted simulation of the distribution patterns ofthe molar masses of oligosaccharides derived frompolysaccharides with the postulated distributions of uronicacid residues. In the case of native, partially acetylated hemicellulosesisolated by aqueous extraction of spruce and aspen wood chipsemploying microwave treatment, the degree of substitution withacetyl groups (DS) could be calculated from the MALDI-MSspectra recorded before and after deacetylatio, NR 20140805