Biochemistry, histology and clinical uses of chitins and chitosans in wound healing

Trilayer composite scaffold for urethral reconstruction:in vitroevaluation of mechanical, biological, and angiogenic properties

Regeneration of damaged urethral tissue remains a major challenge in the field of lower urinary tract reconstruction. To address this issue, various synthetic and natural biodegradable biomaterials are currently being explored for the fabrication of scaffolds that promote urethral regeneration and healing. In this study, we present an approach to fabricate a trilayer hybrid scaffold comprising a central layer of poly(lactic acid) (PLA) between two layers of chitosan. The chitosan/PLA/chitosan (CPC) scaffolds were fabricated by a sequential electrospinning process and their properties were evaluated for their suitability for urethral tissue engineering. The physical and biological properties of the CPC scaffolds were evaluated in comparison to electrospun PLA scaffolds and acellular dermis (Alloderm) as controls for a synthetic and a natural scaffold, respectively. Compared to the controls, the CPC scaffolds exhibited higher elastic modulus and ultimate tensile strength, while maintaining extensibility and suture retention strength appropriate for clinical use. The CPC scaffolds displayed significant hydrophilicity, which was associated with a higher water absorption capacity of the chitosan nanofibres. The degradation products of the CPC scaffolds did not exhibit cytotoxicity and promoted wound closure by fibroblastsin vitro. In addition, CPC scaffolds showed increased growth of smooth muscle cells, an essential component for functional regeneration of urethral tissue. Furthermore, in a chicken embryo-based assay, CPC scaffolds demonstrated significantly higher angiogenic potential, indicating their ability to promote vascularisation, a crucial aspect for successful urethral reconstruction. Overall, these results suggest that CPC hybrid scaffolds containing both natural and synthetic components offer significant advantages over conventional acellular or synthetic materials alone. CPC scaffolds show promise as potential candidates for further research into the reconstruction of the urethrain vivo.

Evaluation of the antiparasitic activity of the chitosan-silver nanocomposites in the treatment of experimentally infested pigeons with Pseudolynchia canariensis

This study aimed to evaluate the efficacy of chitosan-silver nanocomposites in the treatment of experimentally infested pigeons with Pseudolynchia canariensis (P. canariensis) with evaluation of different immunological parameters before and after treatment. Therefore, fourteen birds were divided into 2 groups; group1(infested group including 12 birds) which subdivided into 6 sub-groups experimentally infested pigeons 2 pigeons each, and five group of them were treated with chitosan-silver nanocomposites and sub-group number 6 was treated with deltamethrin while, group 2 including two pigeons were kept as control negative ones. P. canariensis flies distributed under the wing and /or under the tail in infested group and these pigeons showed significantly lower RBCs and higher WBCs than that in non-infested pigeons. The cell mediated immune response against experimentally infested pigeons with P. canariensis was studied. P. canariensis infestation in pigeons have a negative impact on pigeon’s blood parameters, increase TNF-α and IL-1β cytokines levels. This study cleared out the role of P. canariensis in the induction of a case of oxidative stress indicated by high level of nitric oxide and malondialdehyde (MDA) with low antioxidant capacity in shape of reduced zinc concentration in the sera of experimentally infested pigeon. Chitosan-silver nanocomposite has a promising effect in the elimination of P. canariensis infestation in pigeons.

RETRACTED: Investigation of the Potential of Nebivolol Hydrochloride-Loaded Chitosomal Systems for Tissue Regeneration: In Vitro Characterization and In Vivo Assessment

In this study, we evaluated the synergistic effect of nebivolol hydrochloride (NVH), a third-generation beta-blocker and NO donor drug, and chitosan on the tissue regeneration. Ionic gelation method was selected for the preparation of NVH-loaded chitosomes using chitosan lactate and sodium tripolyphosphate. The effect of different formulation variables was studied using a full factorial design, and NVH entrapment efficiency percentages and particle size were selected as the responses. The chosen system demonstrated high entrapment efficiency (73.68 ± 3.61%), small particle size (404.05 ± 11.2 nm), and good zeta potential value (35.6 ± 0.25 mV). The best-achieved formula demonstrated spherical morphology in transmission electron microscopy and amorphization of the crystalline drug in differential scanning calorimetry and X-ray diffraction. Cell culture studies revealed a significantly higher proliferation of the fibroblasts in comparison with the drug suspensions and the blank formula. An in vivo study was conducted to compare the efficacy of the proposed formula on wound healing. The histopathological examination showed the superiority of NVH-loaded chitosomes on the wound proliferation and the non-significant difference in the collagen deposition after 15 days of the injury to that of intact skin. In conclusion, NVH-loaded chitosomes exhibited promising results in enhancing skin healing and tissue regeneration.

A High-Throughput Screening System Based on Fluorescence-Activated Cell Sorting for the Directed Evolution of Chitinase A

Chitinases catalyze the degradation of chitin, a polymer of N-acetylglucosamine found in crustacean shells, insect cuticles, and fungal cell walls. There is great interest in the development of improved chitinases to address the environmental burden of chitin waste from the food processing industry as well as the potential medical, agricultural, and industrial uses of partially deacetylated chitin (chitosan) and its products (chito-oligosaccharides). The depolymerization of chitin can be achieved using chemical and physical treatments, but an enzymatic process would be more environmentally friendly and more sustainable. However, chitinases are slow-acting enzymes, limiting their biotechnological exploitation, although this can be overcome by molecular evolution approaches to enhance the features required for specific applications. The two main goals of this study were the development of a high-throughput screening system for chitinase activity (which could be extrapolated to other hydrolytic enzymes), and the deployment of this new method to select improved chitinase variants. We therefore cloned and expressed the Bacillus licheniformis DSM8785 chitinase A (chiA) gene in Escherichia coli BL21 (DE3) cells and generated a mutant library by error-prone PCR. We then developed a screening method based on fluorescence-activated cell sorting (FACS) using the model substrate 4-methylumbelliferyl β-d-N,N′,N″-triacetyl chitotrioside to identify improved enzymes. We prevented cross-talk between emulsion compartments caused by the hydrophobicity of 4-methylumbelliferone, the fluorescent product of the enzymatic reaction, by incorporating cyclodextrins into the aqueous phases. We also addressed the toxicity of long-term chiA expression in E. coli by limiting the reaction time. We identified 12 mutants containing 2–8 mutations per gene resulting in up to twofold higher activity than wild-type ChiA.

Physical characterization of chitosan/gelatin-alginate composite beads for controlled release of urea

Polymer-based controlled-release formulations are gaining significant advantage over chemical fertilizers in recent years as they contribute to the preservation of soil fertility by reducing soil pollution in farm lands. In this work, urea (a nitrogen source fertilizer) has been entrapped within chitosan-alginate and gelatin-alginate composite beads at three different concentrations. The physical properties of the polymer composite beads namely the diameter, porosity, yield percentage, Carr's index and Hausner's ratio were determined. These fertilizer-loaded beads were also characterized by Scanning Electron Microscopy (SEM) and Fourier Transform-Infra Red (FT-IR) spectroscopy. Urea enhanced swelling of chitosan-alginate beads through the creation of pores whereas in the case of gelatin-alginate formulations, urea decreased the swelling. The swelling of the polymer composite beads was found to be maximum at pH of 5.6 when compared to that of pH conditions, 7 and 8.5. The chitosan-alginate composite beads were found to possess better fertilizer entrapping efficiency than the gelatin-alginate composite beads. The in vitro urea release studies demonstrated that the urea-entrapped gelatin-alginate beads exhibited slower urea release than that of the chitosan-alginate beads. These controlled release urea formulations were found to follow quasi-fickian diffusion mechanism.

Chitosan-based particulate systems for drug and vaccine delivery in the treatment and prevention of neglected tropical diseases

Neglected tropical diseases (NTDs) are a diverse group of infections which are difficult to prevent or control, affecting impoverished communities that are unique to tropical or subtropical regions. In spite of the low number of drugs that are currently used for the treatment of these diseases, progress on new drug discovery and development for NTDs is still very limited. Therefore, strategies on the development of new delivery systems for current drugs have been the main focus of formulators to provide improved efficacy and safety. In recent years, particulate delivery systems at micro- and nanosize, including polymeric micro- and nanoparticles, liposomes, solid lipid nanoparticles, metallic nanoparticles, and nanoemulsions, have been widely investigated in the treatment and control of NTDs. Among these polymers used for the preparation of such systems is chitosan, which is a marine biopolymer obtained from the shells of crustaceans. Chitosan has been investigated as a delivery system due to the versatility of its physicochemical properties as well as bioadhesive and penetration-enhancing properties. Furthermore, chitosan can be also used to improve treatment due to its bioactive properties such as antimicrobial, tissue regeneration, etc. In this review, after giving a brief introduction to neglected diseases and particulate systems developed for the treatment and control of NTDs, the chitosan-based systems will be described in more detail and the recent studies on these systems will be reviewed. Graphical abstract.

Noncovalent Sericin-Chitosan Scaffold: Physical Properties and Low Cytotoxicity Effect

This research aims to utilize sericin, which is the waste from boiling silk cocoon, for the supramolecular scaffold preparation with chitosan. A suitable method for the self-assembled scaffold formation of sericin and chitosan at 1:1 stoichiometry is presented and the morphological and physical properties of the scaffold are studied. The effect of an alcohol/NaOH solution on the secondary structure of sericin protein within the sericin-chitosan scaffold, with adjusted pH, was investigated. Additionally, the scaffold was tested in a native phosphate buffer solution (PBS). The results show that sericin increases the porosity of scaffold while chitosan increases the rigidity. The self-assembled sericin and chitosan material is nontoxic to human cells and which can adhere and spread well on such support. For the effect of the molecular weight of chitosan (15,000 and 100,000 g/mol), the scaffold made from lower molecular weight (MW) chitosan provides a somewhat smaller porosity, but a similar swelling ratio and water uptake. On the basis of this research, sericin, which is a silk waste from the textile industry, can be utilized to produce a self-assembled scaffold with chitosan in order to increase the porosity of the scaffold. This type of scaffold is not toxic and can be used for the adhesion of fibroblast cells.

Chitosan-induced Synergy for Extended Antimicrobial Potency and Enhanced In Vitro Drug Release of Free Base Ciprofloxacin Nanoplexes

BACKGROUND

Ciprofloxacin free base is practically insoluble in aqueous medium (0.0011 and 0.09 mg/mL at 25 and 37°C respectively). Its inorganic salt form (ciprofloxacin hydrochloride) is more soluble in water (1.35 mg/mL) however when administered orally, it exhibits decreased solubility in the stomach due to common ion effects. Ciprofloxacin free base was used in this study because of its greater hydrophobicity than its hydrochloride salt, which is required for effective permeability and potent antibacterial activity.

OBJECTIVE

The purpose of this study is to enhance oral solubility and bacterial cell permeability of the free base ciprofloxacin (CPX) using a single step CPX-chitosan (CT) selfassembly to form nanoplexes with organic counterions. It was envisioned that this would allow the delivery of larger amounts of active drug into the microorganisms.

METHODS

Ciprofloxacin-chitosan nanocomplex (nanoplex) was prepared using low energy electrostatic self-assembly technique previously described. Formation of eutectic nanoplex was confirmed using FTIR, DSC, TGA and SEM. The saturated solubility, in vitro release kinetics and mechanism of drug release were determined using mathematical models. Potency and synergism were determined from the inhibition zones, minimum inhibitory concentration (MIC) and Fractional Inhibitory Concentration (FIC) of the nanoplexes using Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.

RESULTS

Formation of CPX-CT eutectic adduct polymeric nanoplexes was confirmed with FT-IR and DSC and SEM revealed the conversion of rod-like crystals of CPX (117 μm long) into spherical nanostructures (23-503 nm) dictated by pH, ionic strength and concentration of CT. The solubility of free base CPX increased to a maximum of 32.77 mg/mL compared to 0.0011-0.09 mg/mL reported in literature and dissolution efficiency increased to a maximum of 100% within 72 h. The synergistic effect of CT on antimicrobial activity of CPX was quantified, for the first time, using Fractional Inhibitory Concentration (FIC) of the nanoplexes. FIC was less than 0.5 in both Gram positive (0.031-0.250) and Gram negative (0.036-0.281) microorganisms used in this study, confirming synergistic enhancement of antimicrobial efficacy of CPX.

CONCLUSION

It is evident that the design of drug-polymer nanocomplex formulation provides a platform for the synergistic enhancement of therapeutic potency of antibiotics.

Nanohybrid Scaffold of Chitosan and Functionalized Graphene Oxide for Controlled Drug Delivery and Bone Regeneration

Nanohybrid scaffolds of chitosan have been designed for controlled drug delivery and bone regeneration. Sulfonated graphene oxide has been used to develop the nanohybrids. Nanohybrid scaffolds show highly hydrophilic character and greater mechanical strength as compared to pure chitosan. Nanohybrid scaffolds show an interconnected uniform porous network structure exhibiting sustained release kinetics of the antibacterial drug, tetracycline hydrochloride. Nanohybrids are found to be highly biocompatible in nature and are able to support and proliferate MG63 osteoblast cells and thereby induce bone tissue regeneration. The in-vivo bone healing study shows that the developed nanohybrid scaffolds have the potential to regenerate the bone faster without any side effects as compared to pure scaffolds. Hence, the developed nanohybrid scaffold has good potential as a controlled drug delivery vehicle and in bone tissue engineering for faster healing.

Electrospun Bilayer Chitosan/Hyaluronan Material and Its Compatibility with Mesenchymal Stem Cells

A bilayer nonwoven material for tissue regeneration was prepared from chitosan (CS) and hyaluronic acid (HA) by needleless electrospinning wherein 10-15 wt% (with respect to polysaccharide) polyethylene oxide was added as spinning starter. A fiber morphology study confirmed the material's uniform defect-free structure. The roughness of the bilayer material was in the range of 1.5-3 μm, which is favorable for cell growth. Electrospinning resulted in the higher orientation of the polymer structure compared with that of corresponding films, and this finding may be related to the orientation of the polymer chains during the spinning process. These structural changes increased the intermolecular interactions. Thus, despite a high swelling degree of 1.4-2.8 g/g, the bilayer matrix maintained its shape due to the large quantity of polyelectrolyte contacts between the chains of oppositely charged polymers. The porosity of the bilayer CS-HA nonwoven material was twice lower, while the Young's modulus and break stress were twice higher than that of a CS monolayer scaffold. Therefore, during the electrospinning of the second layer, HA may have penetrated into the pores of the CS layer, thereby increasing the polyelectrolyte contacts between the two polymers. The bilayer CS-HA scaffold exhibited good compatibility with mesenchymal stem cells. This characteristic makes the developed material promising for tissue engineering applications.

Biomedical Applications of Chitosan and Its Derivative Nanoparticles

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely difficult to solubilize in water, but it can be solubilized in acidic solution. Its insolubility in water is a major limitation for its use in medical applications. Chitosan derivatives can be obtained by chemical modification using such techniques as acylation, alkylation, sulfation, hydroxylation, quaternization, esterification, graft copolymerization, and etherification. Modified chitosan has chemical properties superior to unmodified chitosan. For example, nanoparticles produced from chitosan derivatives can be used to deliver drugs due to their stability and biocompatibility. This review mainly focuses on the properties of chitosan, chitosan derivatives, and the origin of chitosan-based nanoparticles. In addition, applications of chitosan-based nanoparticles in drug delivery, vaccine delivery, antimicrobial applications, and callus and tissue regeneration are also presented. In summary, nanoparticles based on chitosan have great potential for research and development of new nano vaccines and nano drugs in the future.

Antibacterial Effects of Chitosan, Formocresol and CMCP as Pulpectomy Medicament on Enterococcus‎faecalis, Staphylococcus aureus and Streptococcus‎mutans

INTRODUCTION

During pulpectomy of primary teeth, cytotoxic medicaments such as formocresol or camphor mono-chlorophenol (CMCP) are used as medicaments. For the first time it is theorized that chitosan can substitute these traditional materials used in pulpectomy of infectious primary teeth.

METHODS AND MATERIALS

This preliminary in vitro study consisted of two separate phases (n=75), each of which assessed the antibacterial effects of chitosan versus formocresol and CMCP and positive/negative controls (n=15) on three bacteria types [Enterococcus‎faecalis, Staphylococcus aureus, Streptococcus‎mutans, (n=5 per subgroup)]. Phases 1 and 2 concerned respectively with 1- and 7-day effects of these materials. Bacteria were cultured and injected into sterilized canals and colonies were counted. Medicaments were applied and colonies were re-counted after 1 day of treatment (phase 1). Specimens were re-sterilized and re-randomized, and used for phase 2, in which the same procedures were performed for a 7-day period. Effects of agents on bacteria were analyzed statistically (Kruskal-Wallis α=0.05 and Mann-Whitney α=0.017).

RESULTS

Treatments reduced bacterial count either after 1 or 7 days (P=0.000). Their effects on different bacteria types were not significant either after 1 or 7 days (P>0.48). Antibacterial efficacies of treatments (indicated by colony reduction) were significantly different, after 7 days (P=0.045). Antibacterial efficacy of chitosan was similar to that of formocresol or CMCP, in both phases [either after 1 or 7 days of treatment (P>0.017). Formocresol and CMCP had similar efficacies in either phase (P>0.017).

CONCLUSIONS

This preliminary study confirmed the appropriate antibacterial efficacy of chitosan as a medicament in pulpectomy of infectious primary teeth.

Chitin and chitosan: biopolymers for wound management

Chitin and chitosan are biopolymers with excellent bioactive properties, such as biodegradability, non-toxicity, biocompatibility, haemostatic activity and antimicrobial activity. A wide variety of biomedical applications for chitin and chitin derivatives have been reported, including wound-healing applications. They are reported to promote rapid dermal regeneration and accelerate wound healing. A number of dressing materials based on chitin and chitosan have been developed for the treatment of wounds. Chitin and chitosan with beneficial intrinsic properties and high potential for wound healing are attractive biopolymers for wound management. This review presents an overview of properties, biomedical applications and the role of these biopolymers in wound care.

Polyethylenimine-dermatan sulfate complex, a bioactive biomaterial with unique toxicity to CD146-positive cancer cells

We report unique bioactivity of a polycation-polyanion complex with potential utility for cancer therapy. A complex of disulfide-crosslinked polyethyleneimine (CLPEI), a polycation used for gene complexation, and dermatan sulfate (DS), an anionic polysaccharide to shield excessive cationic charge of the former, has toxicity to a specific group of cancer cell lines, including B16-F10 murine melanoma, A375SM human melanoma, and PC-3 human prostate cancer cells. These CLPEI-DS-sensitive cells express CD146, which binds to the complex via interaction with DS. There is a positive correlation between toxicity and intracellular level of CLPEI, indicating that the CLPEI-DS-sensitivity is attributable to the increased cellular uptake of CLPEI mediated by the DS-CD146 interactions. In vitro studies show that CLPEI-DS complex causes G₀/G₁ phase arrest and apoptotic cell death. In syngeneic and allograft models of B16-F10 melanoma, CLPEI-DS complex administered with a sub-toxic level of doxorubicin potentiates the chemotherapeutic effect of the drug by loosening tumor tissues. Given the unique toxicity, CLPEI-DS complex may be a useful carrier of gene or chemotherapeutics for the therapy of CD146-positive cancers.

Perspectives on: Chitosan Drug Delivery Systems Based on their Geometries

Chitosan is a natural polymer that has many physicochemical (polycationic, reactive OH and NH2 groups) and biological (bioactive, biocompatible, biodegradable) properties. These unique properties make chitosan an excellent material for the development of new biomedical applications. One of the most well known biomedical chitosan applications is in drug delivery systems. Chitosans have been used in the design of many different types of drug carriers for various administration routes such as oral, bucal, nasal, transdermal, parenteral, vaginal, cervical, intrauterine and rectal. Chitosan can be engineered into different shapes and geometries such as nanoparticles, microspheres, membranes, sponges and rods. This paper is a perspective on the preparation of the chitosan drug delivery systems based on different structural geometries. In this respect, special preparation techniques are used to prepare chitosan drug carriers by altering such parameters as crosslinker concentration, chitosan molecular weight, drug/polymer ratio and processing conditions all of which affect the morphology of chitosan drug carriers and release rate of the loaded drug.

Chitosan as a Biomaterial: Influence of Degree of Deacetylation on Its Physiochemical, Material and Biological Properties

Chitosan is a biomaterial with a range of current and potential biomedical applications. Manipulation of chitosan degree of deacetylation (DDA) to achieve specific properties appears feasible, but studies investigating its influence on properties are often contradictory. With a view to the potential of chitosan in the regeneration of nerve tissue, the influence of DDA on the growth and health of olfactory ensheathing cells (OECs) was investigated. There was a linear increase in OEC proliferation as the DDA increased from 72 to 85%. This correlated with linear increases in average surface roughness (0.62 to 0.78 μm) and crystallinity (4.3 to 10.1%) of the chitosan films. Mitochondrial activity and membrane integrity of OECs was significantly different for OECs cultivated on chitosan with DDAs below 75%, while those on films with DDAs up to 85% were similar to cells in asynchronous growth. Apoptotic indices and cell cycle analysis also suggested that chitosan films with DDAs below 75% were cytocompatible but induced cellular stress, while OECs grown on films fabricated from chitosan with DDAs above 75% showed no significant differences compared to those in asynchronous growth. Tensile strength and elongation to break varied with DDA from 32.3 to 45.3 MPa and 3.6 to 7.1% respectively. DDA had no significant influence on abiotic and biotic degradation profiles of the chitosan films which showed approximately 8 and 20% weight loss respectively. Finally, perceived patterns in property changes are subject to change based on potential variations in DDA analysis. NMR examination of the chitosan samples here revealed significant differences depending upon which peaks were selected for integration; 6 to 13% in DDA values within individual samples. Furthermore, differences between DDA values determined here and those reported by the commercial suppliers were significant and this may also be a source of concern when selecting commercial chitosans for biomaterial research.

Chitosan: An Update on Potential Biomedical and Pharmaceutical Applications

Chitosan is a natural polycationic linear polysaccharide derived from chitin. The low solubility of chitosan in neutral and alkaline solution limits its application. Nevertheless, chemical modification into composites or hydrogels brings to it new functional properties for different applications. Chitosans are recognized as versatile biomaterials because of their non-toxicity, low allergenicity, biocompatibility and biodegradability. This review presents the recent research, trends and prospects in chitosan. Some special pharmaceutical and biomedical applications are also highlighted.

Drug Carriers: Not an Innocent Delivery Man

Biomaterials used as drug carriers are often considered inactive and assumed to have no other roles than modifying pharmacokinetics and biodistribution of a drug. On the other hand, there are several examples in which the carrier materials show bioactivities in the body, which may have been underestimated or inadvertently ignored. This review highlights several examples where biomaterials used as drug carriers bring biological effects, known or newly discovered, and discusses their implications in development of new drug delivery systems.

Nanotechnology in dermatology

The scientific community and general public have been exposed to a series of achievements attributed to a new area of knowledge: Nanotechnology. Both abroad and in Brazil, funding agencies have launched programs aimed at encouraging this type of research. Indeed, for many who come into contact with this subject it will be clear the key role that chemical knowledge will play in the evolution of this subject. And even more, will see that it is a science in which the basic structure is formed by distilling different areas of inter-and multidisciplinary knowledge along the lines of new paradigms. In this article, we attempt to clarify the foundations of nanotechnology, and demonstrate their contribution to new advances in dermatology as well as medicine in general. Nanotechnology is clearly the future.

Suppressive effects of D-glucosamine on the 5-HT sensitive nociceptive units in the rat tooth pulpal nerve

It is well known that D-glucosamine hydrochloride (DGL) has a variety of biological activities and is regarded as a nutritional supplement effective in improving various disorders, including osteoarthritis and atherosclerosis. Although it has been reported that DGL has a significant pain relief effect in treating osteoarthritis, little is known about the characteristics of the effects of this compound on dental pain. The present study was undertaken to evaluate the applicability of DGL as a medicament to control pulpalgia. Using an in vitro rat mandible-inferior alveolar nerve preparation (jaw-nerve preparation), we evaluated the effects of DGL on 5-hydroxytryptamine (5-HT) sensitive nociceptive responses in the tooth pulpal nerve. 5-HT-induced nociceptive responses were fairly suppressed by direct application of DGL, suggesting that DGL have a pain relief effect on patients with dental pain.

Biopolymer/Calcium phosphate scaffolds for bone tissue engineering

With nearly 30 years of progress, tissue engineering has shown promise in developing solutions for tissue repair and regeneration. Scaffolds, together with cells and growth factors, are key components of this development. Recently, an increasing number of studies have reported on the design and fabrication of scaffolding materials. In particular, inspired by the nature of bone, polymer/ceramic composite scaffolds have been studied extensively. The purpose of this paper is to review the recent progress of the naturally derived biopolymers and the methods applied to generate biomimetic biopolymer/calcium phosphate composites as well as their biomedical applications in bone tissue engineering.

D-glucosamine promotes transfection efficiency during electroporation

D-Glucosamine is a useful medicament in various fields of medicine and dentistry. With respect to stability of the cell membrane, it has been reported that bradykinin-induced nociceptive responses are significantly suppressed by the direct application of D-glucosamine. Electroporation is usually used to effectively introduce foreign genes into tissue culture cells. Buffers for electroporation with or without D-glucosamine are used in experiments of transfection vectors. This is the first study to indirectly observe the stability and protection of the osteoblast membrane against both electric stress and gene uptake (the proton sponge hypothesis: osmotic rupture during endosomes prior to fusion with lysosomes) in electroporation with D-glucosamine application. The transfection efficiency was evaluated as the fluorescence intensity of the transfected green fluorescent protein (GFP) in the cultured cells (osteoblasts; NOS-1 cells). The transfection efficiency increased over 30% in the electroporation samples treated with D-glucosamine-supplemented buffer after one day. The membrane absorption of D-glucosamine is the primary mechanism of membrane stress induced by electric stress. This new function of D-glucosamine is useful and meaningful for developing more effective transformation procedures.

A novel chitosan-γPGA polyelectrolyte complex hydrogel promotes early new bone formation in the alveolar socket following tooth extraction

A novel chitosan-γPGA polyelectrolyte complex hydrogel (C-PGA) has been developed and proven to be an effective dressing for wound healing. The purpose of this study was to evaluate if C-PGA could promote new bone formation in the alveolar socket following tooth extraction. An animal model was proposed using radiography and histomorphology simultaneously to analyze the symmetrical sections of Wistar rats. The upper incisors of Wistar rats were extracted and the extraction sockets were randomly treated with gelatin sponge, neat chitosan, C-PGA, or received no treatment. The extraction sockets of selected rats from each group were evaluated at 1, 2, 4, or 6 wk post-extraction. The results of radiography and histopathology indicated that the extraction sockets treated with C-PGA exhibited lamellar bone formation (6.5%) as early as 2 wk after the extraction was performed. Moreover, the degree of new bone formation was significantly higher (P < 0.05) in the extraction sockets treated with C-PGA at 6 wk post-extraction than that in the other study groups. In this study, we demonstrated that the proposed animal model involving symmetrical sections and simultaneous radiography and histomorphology evaluation is feasible. We also conclude that the novel C-PGA has great potential for new bone formation in the alveolar socket following tooth extraction.

Chitinolytic microorganisms and their possible application in environmental protection

This paper provides a review of the latest research findings on the applications of microbial chitinases to biological control. Microorganisms producing these enzymes can inhibit the growth of many fungal diseases that pose a serious threat to global crop production. Currently, efforts are being made to discover producers of chitinolytic enzymes. The potential exists that natural biofungicides will replace chemical fungicides or will be used to supplement currently used fungicides, which would reduce the negative impact of chemicals on the environment and support the sustainable development of agriculture and forestry.

PEM anchorage on titanium using catechol grafting

BACKGROUND

This study deals with the anchorage of polyelectrolyte films onto titanium surfaces via a cathecol-based linker for biomedical applications.

METHODOLOGY

The following study uses a molecule functionalized with a catechol and a carboxylic acid: 3-(3,4-dihydroxyphenyl)propanoic acid. This molecule is anchored to the TiO(2) substrate via the catechol while the carboxylic acid reacts with polymers bearing amine groups. By providing a film anchorage of chemisorption type, it makes possible to deposit polyelectrolytes on the surface of titanium.

PRINCIPAL FINDINGS

Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) measurements show that the different steps of grafting have been successfully performed.

CONCLUSIONS

This method based on catechol anchorage of polyelectrolytes open a window towards large possibilities of clinical applications.

Preparation and Performance Evaluation of the Analgesic and Anti-Inflammatory Effects of Chitosan Composite Materials

The author had used salivation method to prepareQuercetin-ornidazole-chitosan composite material (QOCCM) and then used this film to the treatment for the rat model of oral ulcer. and finally found that it can promote the healing of ulcers. In order to investigate the mechanism of action in the treatment of oral ulcers, we prepare Quercetin-ornidazole-chitosan complex solution, and then used the application of carrageenan induced paw edema and croton oil-induced mouse ear swelling to observe its anti-inflammatory role, application of hot plate method to observe the analgesic effect of inflammatory and evaluate the effects of chitosan composite materials.

Functionalization of titanium with chitosan via silanation: evaluation of biological and mechanical performances

Complications in dentistry and orthopaedic surgery are mainly induced by peri-implant bacterial infections and current implant devices do not prevent such infections. The coating of antibacterial molecules such as chitosan on its surface would give the implant bioactive properties. The major challenge of this type of coating is the attachment of chitosan to a metal substrate. In this study, we propose to investigate the functionalization of titanium with chitosan via a silanation. Firstly, the surface chemistry and mechanical properties of such coating were evaluated. We also verified if the coated chitosan retained its biocompatibility with the peri-implant cells, as well as its antibacterial properties. FTIR and Tof-SIMS analyses confirmed the presence of chitosan on the titanium surface. This coating showed great scratch resistance and was strongly adhesive to the substrate. These mechanical properties were consistent with an implantology application. The Chitosan-coated surfaces showed strong inhibition of Actinomyces naeslundii growth; they nonetheless showed a non significant inhibition against Porphyromonas gingivalis after 32 hours in liquid media. The chitosan-coating also demonstrated good biocompatibility to NIH3T3 fibroblasts. Thus this method of covalent coating provides a biocompatible material with improved bioactive properties. These results proved that covalent coating of chitosan has significant potential in biomedical device implantation.

Physiochemical, optical and biological activity of chitosan-chromone derivative for biomedical applications

This paper describes the physiochemical, optical and biological activity of chitosan-chromone derivative. The chitosan-chromone derivative gels were prepared by reacting chitosan with chromone-3-carbaldehyde, followed by solvent exchange, filtration and drying by evaporation. The identity of Schiff base was confirmed by UV-Vis absorption spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. The chitosan-chromone derivative was evaluated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), photoluminescence (PL) and circular dichroism (CD). The CD spectrum showed the chitosan-chromone derivative had a secondary helical structure. Microbiological screening results demonstrated the chitosan-chromone derivative had antimicrobial activity against Escherichia coli bacteria. The chitosan-chromone derivative did not have any adverse effect on the cellular proliferation of mouse embryonic fibroblasts (MEF) and did not lead to cellular toxicity in MEFs. These results suggest that the chitosan-chromone derivative gels may open a new perspective in biomedical applications.

Use and potential of nanotechnology in cosmetic dermatology

Biotechnology and nanotechnology are the key technologies of the twenty-first century, having enormous potential for innovation and growth. The academic and industrial goals for these technologies are the development of nanoscale biomolecular substances and analytical instruments for investigating cell biology at the cellular and molecular levels. Developments in nanotechnology will provide opportunities for cosmetic dermatology to develop new biocompatible and biodegradable therapeutics, delivery systems and more active compounds. Cosmetics have the primary function of keeping up a good appearance, changing the appearance, or correcting body odors, while maintaining the skin and its surroundings in good conditions. Thus cosmetic dermatology, recognizing the new realities of skin care products, has to emphasize the functional aspects of cosmetics through an understanding of their efficacy and safety in promoting good health. Nanoscience may help the scientific community to find more innovative and efficacious cosmetics. Understanding the physical model of the cell as a machine is essential to understand how all the cell components work together to accomplish a task. The efficacy and safety of new nanomaterials has to be deeply studied by ex vivo tests and innovative laboratory techniques. New delivery systems and natural nanocompounds, such as chitin nanofibrils for wound healing, are being used in cosmetic dermatology with good results, as are nanostructured TiO₂ and ZnO sunscreens. The challenge is open.

Downstream Processing in Marine Biotechnology

Downstream processing is one of the most underestimated steps in bioprocesses and this is not only the case in marine biotechnology. However, it is well known, especially in the pharmaceutical industry, that downstreaming is the most expensive and unfortunately the most ineffective part of a bioprocess. Thus, one might assume that new developments are widely described in the literature. Unfortunately this is not the case. Only a few working groups focus on new and more effective procedures to separate products from marine organisms. A major characteristic of marine biotechnology is the wide variety of products. Due to this variety a broad spectrum of separation techniques must be applied. In this chapter we will give an overview of existing general techniques for downstream processing which are suitable for marine bioprocesses, with some examples focussing on special products such as proteins (enzymes), polysaccharides, polyunsaturated fatty acids and other low molecular weight products. The application of a new membrane adsorber is described as well as the use of solvent extraction in marine biotechnology.

Chitosan membrane as a wound-healing dressing: Characterization and clinical application

Chitosan prepared from natural biopolymer chitin and cast into membranes has been tested as wound dressing at the skin-graft donor site in patients. Bactigras, a commonly used impregnated tulle gras bandage, served as a control. Chitosan membrane, prepared with a 75% degree of deacetylation and a thickness of 10 microm, was used in nonmesh or mesh form. The progress in wound healing was compared by clinical and histological examination. Itching and pain sensitivity of the wound dressed area was scored with the use of a visual analogue scale. Mesh chitosan membrane in contrast to the nonmesh membrane allowed blood to ooze into the surrounding gauze. After 10 days, the chitosan-dressed area had been healed more promptly as compared with the Bactigras dressed area. Moreover, the chitosan mesh membrane showed a positive effect on the re-epithelialization and the regeneration of the granular layer. The data confirm that chitosan mesh membrane is a potential substitute for human wound dressing.

Development of new hydroactive dressings based on chitosan membranes: characterization and in vivo behavior

Different poly(vinyl alcohol) (PVA)/chitosan lactate (ChL)-blended hydrogels containing nitrofurazone as a local anti-infective drug were prepared by the phase-inversion technique. The swelling degree, surface free energy, mechanical properties, and nitrofurazone release of these membranes were determined. Blood compatibility of these systems was evaluated by the open-static platelet adhesion test with whole human blood. The results showed that water absorption into the PVA/ChL membranes slowed down, governed by the rate at which the dressing interacted with the physiological fluid. Swelling degree values up to 200% were observed. The rate of release of nitrofurazone seemed to depend on the ChL percentage on the blend as well as the pH of the solution. The surface free energy values were in the range of 20-30 dynes/cm, which was appropriate for a favorable interaction with blood. From the Young's module curve, it could be seen that elastic hydrogels were obtained with increment of ChL in the PVA/ChL blends. Values of platelet adhesion and whole blood clotting times for the PVA/ChL blends as well as the increase of ChL, which appears to reduce the fibrinogen adsorption on the PVA/ChL membranes, demonstrated that the blood compatibility of PVP/ChL blends is superior to that separated polymers. The results of in vivo experiments in rats were in very good agreement with these observations, suggesting that PVA/ChL may serve as a new type of potential wound-dressing material.

Binding of a highly de-N-acetylated chitosan to Japanese pheasan lysozyme as measured by 1H-NMR spectroscopy

Binding of a highly de-N-acetylated chitosan to Japanese pheasant lysozyme (JPL), which differs from hen egg white lysozyme (HEWL) by nine amino acid substitutions (including Arg114-->His), was investigated by 1H-NMR spectroscopy. The profile of the one-dimensional spectrum of JPL is essentially identical to that of HEWL. Using two-dimensional spectra of JPL and HEWL, several aromatic and aliphatic proton resonances of JPL were assigned by comparison. When a highly de-N-acetylated chitosan (number-average degree of polymerization, about 18; degree of acetylation, 0.04), where the N-acetylated units are predominantly surrounded by de-N-acetylated units (a monoacetylated chitosan), was added to the JPL solution, the NMR signals were clearly affected in Trp28 C5H and Ile98 gammaCH, as in the case of binding to HEWL. The dissociation constant of the monoacetylated chitosan evaluated from the NMR signal responses was calculated to be 0.23+/-0.05 mm (-31.5 kJ/mol), which is similar to that of HEWL (0.11+/-0.02 mm, -33.3 kJ/mol). Thus, the Arg-->His substitution of the 114th amino acid, which participates in sugar residue binding at the right-sided subsite F, did not significantly affect the chitosan binding. In addition, the C2H signal of His114 of JPL was not affected by the chitosan binding. These results suggest that the monoacetylated chitosan binds to subsites E and F through the left-sided binding mode.