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Susceptobility of dibutyryl chitin and regenerated chitin fibre sto deacylation and depolymerization of lipases
No full textDibutyryl chitin obtained by esterification with butyric anhydride and regenerated chitin obtained from dibutyryl chitin by saponification,
both in the form of wet-spun fibres and non-wovens, were examined by infrared spectrometry and X-ray diffraction spectrometry. Chitin
fibres and chitosan fibres were also studied for comparison, and found to maintain the XRD spectral features of the parent chitin and chitosan.
On the opposite, DBC fibres and non-woven exhibited depressed crystallinity, the peak at 0.46–0.47 nm, typical of chitin, being hardly
detectable, while the one usually at ca. 1.00 nm was present at ca. 1.20 nm. Both DBC fibres and non-woven were highly oriented. When
exposed to porcine pancreatic lipase or wheat germ lipase, the DBC fibres gained improved crystallinity with peaks at 1.14–1.18 and
0.41 nm, due to partial regain of chitin structure as a consequence of partial enzymatic removal of butyryl groups, as confirmed by ATRFTIR.
The RC fibres exhibited broad XRD peaks at 0.96 and 0.36 nm; sharper peaks at 0.34, 0.46–0.49 and 0.96 were observed after
exposure to lipases, due to removal of a disordered polymer fraction susceptible to the unspecific enzymatic depolymerization. In fact the RC
fibres were found to have 8% lower degree of acetylation compared to parent chitin, as a consequence of the alkaline regeneration treatment.
In conclusion, these modified chitins are scarcely susceptible to degradation by lipases (besides to lysozyme, as already reported in the
literature); therefore their biochemical significance in wound management seems limited. They, however, appear to be the ideal textile
materials for providing mechanical support to freeze-dried chitosan sponges having amply documented activity in wound healing, and for the
preparation of specialty textiles
Chitosan stabilizes platelet growth factors and modulates stem cell differentiation toward tissue regeneration
No full textThe idea of using chitosan as a functional delivery aid to support simultaneously PRP, stem cells and
growth factors (GF) is associated with the intention to use morphogenic biomaterials to modulate the
natural healing sequence in bone and other tissues. For example, chitosan–chondroitin sulfate loaded
with platelet lysate was included in a poly(d,l-lactate) foam that was then seeded with human adiposederived
stem cells and cultured in vitro under osteogenic stimulus: the platelet lysate provided to the
bone tissue the most suitable assortment of GF which induces the osteogenic differentiation of the mesenchymal
stem cells. PDGF, FGF, IGF and TGF- were protagonists in the repair of callus fractures. The
release of GF from the composites of chitosan–PRP and either nano-hydroxyapatite or tricalcium phosphate
was highly beneficial for enhancing MSC proliferation and differentiation, thus qualifying chitosan
as an excellent vehicle. A number of biochemical characteristics of chitosan exert synergism with stem
cells in the regeneration of soft tissu
Polyuronans obtained by regiospecific oxidation of polysaccharides from Aspergillus niger, trichoderma reesei and Saprolegnia sp.
No full textChitosan taurocholate capacity to bind lipids and to undergo enzymatic hydrolysis: An in vitro model
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