Chitin and chitosan are biopolymers having immense structural possibilities for chemical and mechanical modifications to generate novel properties, functions and applications especially in biomedical ...area. Chitin and chitosan are effective materials for biomedical applications because of their biocompatibility, biodegradability and non-toxicity, apart from their antimicrobial activity and low immunogenicity, which clearly points to an immense potential for future development. These candidate biopolymers can be easily processed into gels, sponges, membranes, beads and scaffolds forms. This review emphasizes recent research on different aspects of chitin and chitosan based nanomaterials, including the preparation and applications of chitin and chitosan based nanofibers, nanoparticles and nanocomposite scaffolds for tissue engineering, wound dressing, drug delivery and cancer diagnosis.
Chitin and its deacetylated derivative, chitosan, are non-toxic, antibacterial, biodegradable and biocompatible biopolymers. Due to these properties, they are widely used for biomedical applications ...such as tissue engineering scaffolds, drug delivery, wound dressings, separation membranes and antibacterial coatings, stent coatings, and sensors. In the recent years, electrospinning has been found to be a novel technique to produce chitin and chitosan nanofibers. These nanofibers find novel applications in biomedical fields due to their high surface area and porosity. This article reviews the recent reports on the preparation, properties and biomedical applications of chitin and chitosan based nanofibers in detail.
Wound dressing is one of the most promising medical applications for chitin and chitosan. The adhesive nature of chitin and chitosan, together with their antifungal and bactericidal character, and ...their permeability to oxygen, is a very important property associated with the treatment of wounds and burns. Different derivatives of chitin and chitosan have been prepared for this purpose in the form of hydrogels, fibers, membranes, scaffolds and sponges. The purpose of this review is to take a closer look on the wound dressing applications of biomaterials based on chitin, chitosan and their derivatives in various forms in detail.
Chitin and chitosan are known to be natural polymers and they are non-toxic, biodegradable and biocompatible. Chemical modification of chitin and chitosan with sulfate to generate new bifunctional ...materials is of interest because the modification would not change the fundamental skeleton of chitin and chitosan, would keep the original physicochemical and biochemical properties and finally would bring new or improved properties. The sulfated chitin and chitosan have a variety of applications, such as, adsorbing metal ions, drug delivery systems, blood compatibility, and antibacterial field. The purpose of this review is to take a closer look about the different synthetic methods and potential applications of sulfated chitin and chitosan. Based on current research and existing products, some new and futuristic approaches in this context area are discussed in detail. From the studies reviewed, we concluded that sulfated chitin and chitosan are promising materials for biomedical applications.
Tumor-associated B7-H1 molecules inhibit antitumor immunity in some malignancies. We found that B7-H1 expression on patient myeloma cells and human myeloma cell lines (HMCLs) was upregulated by ...cultivating the cells with autologous stromal cells and the human stromal cell line HS-5. Among major cytokines produced by HS-5 cells, interleukin (IL)-6-induced B7-H1 expression on HMCLs. Moreover, HS-5 cell-mediated B7-H1 expression was downregulated by inhibiting IL-6. B7-H1(+) HMCLs were more proliferative and less susceptible to antimyeloma chemotherapy compared with B7-H1(-) HMCLs. Moreover, the former cells showed higher levels of Bcl-2 and FasL expression than the latter. Finally, B7-H1 molecules on HMCLs induced T-cell apoptosis and anergy of tumor-specific T cells. Consistent with these in vitro observations, patients whose myeloma cells expressed high levels of B7-H1 had higher myeloma cell percentages in the bone marrow (BM) and higher serum lactate dehydrogenase levels compared with other myeloma patients. In addition, B7-H1 expression levels were often upregulated after myeloma patients relapsed or became refractory to therapy. Our data indicate that the BM microenvironment upregulates B7-H1 expression on myeloma cells, which links to the two biological actions of inducing T-cell downregulation and enhancing aggressive myeloma-cell characteristics. Modulating the B7-H1 pathway may be worthwhile in myeloma.
Carboxymethyl chitosan derivatives are widely used for biomedical applications because of their non-toxic and biodegradable properties. Curcumin is a phytochemical with immense biological properties. ...But its hydrophobicity and poor oral bioavailability limits its application as a chemotherapeutic agent. To increase the oral bioavailability, we developed curcumin loaded
O-CMC nanoparticles (curcumin-
O-CMC Nps). The prepared nanoparticles were characterized by DLS, AFM, SEM, FT-IR, XRD and TG/DTA. Size analysis studies revealed spherical particles with mean diameter of about 150
±
30
nm. Curcumin was entrapped in
O-CMC with an efficiency of 87%.
In vitro drug release profile was studied at 37
°C under different pHs (7.4 and 4.5) with and without lysozyme. Cytotoxicity studies by MTT assay indicated that curcumin-
O-CMC Nps were toxic to cancer and non-toxic to normal cells. Cellular uptake of the curcumin-
O-CMC Nps was analyzed by fluorescence microscopy and FACS. Overall these studies indicated
O-CMC as a promising nanomatrix for drug delivery applications.
Bioactive glass ceramic nanoparticles (nBGC) were synthesized by sol–gel process and characterized using FTIR, TEM and XRD. Composite scaffolds of chitosan (CS)–gelatin (CG) with nBGC were prepared ...by blending of chitosan and gelatin with nBGC. The prepared CG/nBGC nano-composite scaffolds were characterized using FTIR, SEM and XRD. The effect of nBGC in the scaffold matrix was evaluated in terms of scaffold properties and biocompatibility. Our results showed macroporous internal morphology in the scaffold with pore size ranging from 150 to 300
μm. Degradation and swelling behavior of the nano-composite scaffolds were decreased, while protein adsorption was increased with the addition of nBGC. Biomineralization studies showed higher amount of mineral deposits on the nano-composite scaffold, which increases with increasing time of incubation. MTT assay, direct contact test, and cell attachment studies indicated that, the nano-composite scaffolds are better in scaffold properties and it provides a healthier environment for cell attachment and spreading. So, the developed nano-composite scaffolds are a potential candidate for alveolar bone regeneration applications.
Chitosan is a novel biocompatible, biodegradable polymer for potential use in tissue engineering. In this work, chitosan–gelatin/nanophase hydroxyapatite composite scaffolds were prepared by blending ...chitosan and gelatin with nanophase hydroxyapatite (nHA). The prepared nHA was characterized using TEM, XRD and FT-IR. The prepared composite scaffolds were characterized using SEM, FT-IR and XRD studies. The composite scaffolds were highly porous with a pore size of 150–300
μm. In addition, density, swelling ratio, degradation, biomineralization, cytotoxicity and cell attachment of the composite scaffolds were studied. The scaffolds showed good swelling character, which could be modulated by varying ratio of chitosan and gelatin. Composite scaffolds in the presence of nHA showed a decreased degradation rate and increased mineralization in SBF. The biological response of MG-63 cells on nanocomposite scaffolds was superior in terms of improved cell attachment, higher proliferation, and spreading compared to chitosan–gelatin (CG) scaffold.
Chitosan (CS) is a naturally occurring biopolymer. It has important biological properties such as biocompatibility, antifungal and antibacterial activity, wound healing ability, anticancerous ...property, anticholesteremic properties, and immunoenhancing effect. Recently, CS nanoparticles have been used for biomedical applications. However, due to the limited solubility of CS in water its water-soluble derivatives are preferred for the above said applications. In this work, the nanoparticles of CS and its water-soluble derivatives such as
O-carboxymethyl chitosan (
O-CMC) and
N,O-carboxymethyl chitosan (
N,O-CMC) was synthesized and characterized. In addition, cytotoxicity and antibacterial activity of the prepared nanoparticles was also evaluated for biomedical applications.
Singlet fission, the spin-allowed photophysical process converting an excited singlet state into two triplet states, has attracted significant attention for device applications. Research so far has ...focused mainly on the understanding of singlet fission in pure materials, yet blends offer the promise of a controlled tuning of intermolecular interactions, impacting singlet fission efficiencies. Here we report a study of singlet fission in mixtures of pentacene with weakly interacting spacer molecules. Comparison of experimentally determined stationary optical properties and theoretical calculations indicates a reduction of charge-transfer interactions between pentacene molecules with increasing spacer molecule fraction. Theory predicts that the reduced interactions slow down singlet fission in these blends, but surprisingly we find that singlet fission occurs on a timescale comparable to that in pure crystalline pentacene. We explain the observed robustness of singlet fission in such mixed films by a mechanism of exciton diffusion to hot spots with closer intermolecular spacings.
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