Morphological study of bone regeneration in the presence of 6-oxychitin

Preparation of 6-carboxyl chitin and its effects on cell proliferation in vitro

This study concerns the performance evaluation of 6-carboxyl chitin for its wound healing application. 6-Carboxyl chitins were prepared by the oxidation of chitin at C-6 with NaClO/TEMPO/NaBr after α-chitin was pretreated in NaOH/urea solution. The products with different molecular weights were obtained by changing reaction conditions. They all were completely oxidized at C-6 and N-acetylated at C-2 according to FT-IR and NMR results. 6-Carboxyl chitins could stimulate significantly the proliferation of human skin fibroblasts (HSF) and human keratinocytes (HaCaT), and the bioactivities were concentration and Mws dependent. Within the scope of the study, 10-40 kDa of Mws and 10-100 μg/mL of concentrations were most suitable for the HSF proliferation, but the proliferation of HaCaT increased with decreasing the concentration and Mw. In addition, 6-carboxyl chitins could also induce macrophages and fibroblasts to secrete growth factors. Therefore, 6-carboxyl chitins could be expected to be an active ingredient for wound healing.

Crab vs. Mushroom: A Review of Crustacean and Fungal Chitin in Wound Treatment

Chitin and its derivative chitosan are popular constituents in wound-treatment technologies due to their nanoscale fibrous morphology and attractive biomedical properties that accelerate healing and reduce scarring. These abundant natural polymers found in arthropod exoskeletons and fungal cell walls affect almost every phase of the healing process, acting as hemostatic and antibacterial agents that also support cell proliferation and attachment. However, key differences exist in the structure, properties, processing, and associated polymers of fungal and arthropod chitin, affecting their respective application to wound treatment. High purity crustacean-derived chitin and chitosan have been widely investigated for wound-treatment applications, with research incorporating chemically modified chitosan derivatives and advanced nanocomposite dressings utilizing biocompatible additives, such as natural polysaccharides, mineral clays, and metal nanoparticles used to achieve excellent mechanical and biomedical properties. Conversely, fungi-derived chitin is covalently decorated with -glucan and has received less research interest despite its mass production potential, simple extraction process, variations in chitin and associated polymer content, and the established healing properties of fungal exopolysaccharides. This review investigates the proven biomedical properties of both fungal- and crustacean-derived chitin and chitosan, their healing mechanisms, and their potential to advance modern wound-treatment methods through further research and practical application.

Emerging biomedical applications of nano-chitins and nano-chitosans obtained via advanced eco-friendly technologies from marine resources

The present review article is intended to direct attention to the technological advances made in the 2010-2014 quinquennium for the isolation and manufacture of nanofibrillar chitin and chitosan. Otherwise called nanocrystals or whiskers, n-chitin and n-chitosan are obtained either by mechanical chitin disassembly and fibrillation optionally assisted by sonication, or by e-spinning of solutions of polysaccharides often accompanied by poly(ethylene oxide) or poly(caprolactone). The biomedical areas where n-chitin may find applications include hemostasis and wound healing, regeneration of tissues such as joints and bones, cell culture, antimicrobial agents, and dermal protection. The biomedical applications of n-chitosan include epithelial tissue regeneration, bone and dental tissue regeneration, as well as protection against bacteria, fungi and viruses. It has been found that the nano size enhances the performances of chitins and chitosans in all cases considered, with no exceptions. Biotechnological approaches will boost the applications of the said safe, eco-friendly and benign nanomaterials not only in these fields, but also for biosensors and in targeted drug delivery areas.

Chitin and chitosan composites for bone tissue regeneration

In the present world, where there is increased obesity and poor physical activity, the occurrence of bone disorders has also been increased steeply. Therefore, a significant progress has been made in organ transplantation, surgical reconstruction, and the use of artificial prostheses to treat the loss or failure of an organ or bone tissue in the recent years. Bone contains considerable amounts of minerals and proteins. The major component of bone is hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] (60-65%) and is one of the most stable forms of calcium phosphate and it occurs along with other materials including collagen, chondroitin sulfate, keratin sulfate, and lipids. To remedy bone defects, new natural and synthetic materials are needed, which will have very similar properties as that of natural bone. Bone tissue engineering is a relatively new and emerging field, which paves the way for bone repair or regeneration. Polymers can serve as a matrix to support cell growth by having various properties such as biocompatibility, biodegradability, porosity, charge, mechanical strength, and hydrophobicity. Considerable attention has been given to chitin and chitosan composite materials and their applications in the field of bone tissue engineering in the recent years, which are natural biopolymers. This chapter reviews the various composites of chitin and chitosan, which are proved to be potential materials for bone tissue regeneration.

Chitosan, hyaluronan and chondroitin sulfate in tissue engineering for cartilage regeneration: a review

Injection of hyaluronan into osteoarthritic joints restores the viscoelasticity, augments the flow of joint fluid, normalizes endogenous hyaluronan synthesis, and improves joint function. Chitosan easily forms polyelectrolyte complexes with hyaluronan and chondroitin sulfate. Synergy of chitosan with hyaluronan develops enhanced performances in regenerating hyaline cartilage, typical results being structural integrity of the hyaline-like neocartilage, and reconstitution of the subchondral bone, with positive cartilage staining for collagen-II and GAG in the treated sites. Chitosan qualifies for the preparation of scaffolds intended for the regeneration of cartilage: it yields mesoporous cryogels; it provides a friendly environment for chondrocytes to propagate, produce typical ECM, and assume the convenient phenotype; it is a good carrier for growth factors; it inactivates metalloproteinases thus preventing collagen degradation; it is suitable for the induction of the chondrogenic differentiation of mesenchymal stem cells; it is a potent means for hemostasis and platelet delivery.

Chitosan-Based Macromolecular Biomaterials for the Regeneration of Chondroskeletal and Nerve Tissue

The use of materials, containing the biocompatible and bioresorbable biopolymer poly(1→4)-2-amino-2-deoxy-β-D-glucan, containing some N-acetyl-glucosamine units (chitosan, CHI) and/or its derivatives, to fabricate devices for the regeneration of bone, cartilage and nerve tissue, was reviewed. The CHI-containing devices, to be used for bone and cartilage regeneration and healing, were tested mainly for in vitro cell adhesion and proliferation and for insertion into animals; only the use of CHI in dental surgery has reached the clinical application. Regarding the nerve tissue, only a surgical repair of a 35 mm-long nerve defect in the median nerve of the right arm at elbow level with an artificial nerve graft, comprising an outer microporous conduit of CHI and internal oriented filaments of poly(glycolic acid), was reported. As a consequence, although many positive results have been obtained, much work must still be made, especially for the passage from the experimentation of the CHI-based devices, in vitro and in animals, to their clinical application.

Chitosan based surfactant polymers designed to improve blood compatibility on biomaterials

We developed chitosan based surfactant polymers that could be used to modify the surface of existing biomaterials in order to improve their blood compatibility. These polymers consist of a chitosan backbone, PEG side chains to repel non-specific protein adsorption, and hexanal side chains to facilitate adsorption and proper orientation onto a hydrophobic substrate via hydrophobic interactions. Since chitosan is a polycationic polymer, and it is thrombogenic, the surface charge was altered to determine the role of this charge in the hemocompatibility of chitosan. Charge had a notable effect on platelet adhesion. The platelet adhesion was greatest on the positively charged surface, and decreased by almost 50% with the neutralization of this charge. A chitosan surface containing the negatively charged SO(3)(-) exhibited the fewest number of adherent platelets of all surfaces tested. Coagulation activation was not altered by the neutralization of the positive charge, but a marked increase of approximately 5-6 min in the plasma recalcification time (PRT) was displayed with the addition of the negatively charged species. Polyethylene (PE) surfaces were modified with the chitosan surfactant resulting in a significant improvement in blood compatibility, which correlated to the increasing PEG content within the polymer. Adsorption of the chitosan surfactants onto PE resulted in approximately an 85-96% decrease in the number of adherent platelets. The surfactant polymers also reduced surface induced coagulation activation, which was indicated by the PEG density dependent increase in PRTs. These results indicate that surface modification with our chitosan based surfactant polymers successfully improves blood compatibility. Moreover, the inclusion of either negatively charged SO(3)(-) groups or a high density of large water-soluble PEG side chains produces a surface that may be suitable for cardiovascular applications.