Physicochemical and cell adhesion properties of chitosan films prepared from sugar and phosphate-containing solutions

3D Printed Chitosan/Alginate Hydrogels for the Controlled Release of Silver Sulfadiazine in Wound Healing Applications: Design, Characterization and Antimicrobial Activity

The growing demand for personalized medicine requires innovation in drug manufacturing to combine versatility with automation. Here, three-dimensional (3D) printing was explored for the production of chitosan (CH)/alginate (ALG)-based hydrogels intended as active dressings for wound healing. ALG hydrogels were loaded with 0.75% w/v silver sulfadiazine (SSD), selected as a drug model commonly used for the therapeutic treatment of infected burn wounds, and four different 3D CH/ALG architectures were designed to modulate the release of this active compound. CH/ALG constructs were characterized by their water content, elasticity and porosity. ALG hydrogels (Young's modulus 0.582 ± 0.019 Mpa) were statistically different in terms of elasticity compared to CH (Young's modulus 0.365 ± 0.015 Mpa) but very similar in terms of swelling properties (water content in ALG: 93.18 ± 0.88% and in CH: 92.76 ± 1.17%). In vitro SSD release tests were performed by using vertical diffusion Franz cells, and statistically significant different behaviors in terms of the amount and kinetics of drugs released were observed as a function of the construct. Moreover, strong antimicrobial potency (100% of growth inhibition) against Staphylococcus aureus and Pseudomonas aeruginosa was demonstrated depending on the type of construct, offering a proof of concept that 3D printing techniques could be efficiently applied to the production of hydrogels for controlled drug delivery.

Current Advances in the Development of Hydrogel-Based Wound Dressings for Diabetic Foot Ulcer Treatment

Diabetic foot ulcers (DFUs) are one of the most prevalent complications associated with diabetes mellitus. DFUs are chronic injuries that often lead to non-traumatic lower extremity amputations, due to persistent infection and other ulcer-related side effects. Moreover, these complications represent a significant economic burden for the healthcare system, as expensive medical interventions are required. In addition to this, the clinical treatments that are currently available have only proven moderately effective, evidencing a great need to develop novel strategies for the improved treatment of DFUs. Hydrogels are three-dimensional systems that can be fabricated from natural and/or synthetic polymers. Due to their unique versatility, tunability, and hydrophilic properties, these materials have been extensively studied for different types of biomedical applications, including drug delivery and tissue engineering applications. Therefore, this review paper addresses the most recent advances in hydrogel wound dressings for effective DFU treatment, providing an overview of current perspectives and challenges in this research field.

Biocompatible 3D Printed Chitosan-Based Scaffolds Containing α-Tocopherol Showing Antioxidant and Antimicrobial Activity

Active dressings acting on multiple fronts are requested in the field of care for chronic skin ulcers in order to ameliorate patient compliance and tissue restoration. Currently, three-dimensional polymeric hydrogels are widely investigated; however, no prototypes aiming to control oxidative stress and bacterial proliferation in the wound bed have been developed up until now. The present work describes the formulation of a novel chitosan-based printable material containing α-tocopherol at stable dosages to obtain reproducible 3D scaffolds possessing antioxidant and antimicrobial activity without the use of organic solvents. Stability assays mimicking the manufacturing process and storage conditions reveal no significant drug loss. Chemico-physical characterizations including porosity and behavior after dehydration/hydration demonstrate that the dressings are highly porous, can be dehydrated up to 80%, and can recover more than 90% of water upon 1 h of rehydration. Elasticity determined by stress/strain tests was higher than human skin and was sufficiently resistant for potential clinical manipulation. Footage of fibroblasts in in vitro cultures demonstrated the biocompatibility of the constructs over 28 days. Finally, scaffolds loaded with α-tocopherol showed dose-dependent antioxidant activity (up to 80% in less than 1 h), while antimicrobial action versus multi-drug resistant strains of Pseudomonas aeruginosa and Staphilococcus aureus was assessed by inhibition rings obtained through the Kirby–Bauer technique. The proposed hydrogels can be useful as dressings for the treatment of chronically infected wounds.

Novel polymeric hydrogel composites: Synthesis, physicochemical, mechanical and biocompatible properties

In this research study, novel hydrogel composite films were constructed using different ratios of poly (vinyl alcohol) (PVA)/kappa-carrageenan (KC) (PVA90/KC10%, PVA80/KC20%, PVA70/KC30%, PVA60/KC40%) crosslinked with glutaraldehyde (0.025%) and investigated their physicochemical characteristics such as mechanical, thermal, morphological, swelling behaviour, and cell viability. SEM and FTIR revealed that surface morphology changed to heterogeneous and the presence of molecular interaction among the polymers. PVA90KC10 and PVA60KC40 exhibited smaller and larger pores on surface respectively. The change in the proportion of PVA and KC also triggered the tensile strength (Ts) of the film and the highest Ts observed were 21.60 MPa for PVA60KC40. Moreover, the thermal analysis showed three-phase degradation, and an increase in KC40 concentration results inversely proportional to a decrease in the rate of thermal degradation. Further, swelling and in-vitro biodegradation study confirmed the enhanced perseverance of water uptake for PVA60KC40 (286%) due to pores structure of the hydrogel film and PVA and KC alone degraded faster as compare to other films results suggested higher concentration of PVA90KC10 showed lower degradation rate and highest for PVA60KC40 about 6% and 22% respectively. Further, the cell viability was studied with MTT assay method by using NIH3T3 and HEK-293 cells for biocompatibility study revealed NIH3T3 cells were more biocompatible than HEK-293 and cell viability percent for PVA60KC40 showed the highest cell attachment about 99%. Overall corroborating data obtained from the study attested to the average swelling, appreciable mechanical characters, good interaction between molecules, and cell viability of the constructed PVA/KC hydrogel film, these all characters pave to be used as a potential template for biomedical applications such as tissue engineering and drug delivery.

Cultured Horse Articular Chondrocytes in 3D-Printed Chitosan Scaffold With Hyaluronic Acid and Platelet Lysate

Three-dimensional (3D) printing has gained popularity in tissue engineering and in the field of cartilage regeneration. This is due to its potential to generate scaffolds with spatial variation of cell distribution or mechanical properties, built with a variety of materials that can mimic complex tissue architecture. In the present study, horse articular chondrocytes were cultured for 2 and 4 weeks in 3D-printed chitosan (CH)-based scaffolds prepared with or without hyaluronic acid and in the presence of fetal bovine serum (FBS) or platelet lysate (PL). These 3D culture systems were analyzed in terms of their capability to maintain chondrocyte differentiation in vitro. This was achieved by evaluating cell morphology, immunohistochemistry (IHC), gene expression of relevant cartilage markers (collagen type II, aggrecan, and Sox9), and specific markers of dedifferentiated phenotype (collagen type I, Runx2). The morphological, histochemical, immunohistochemical, and molecular results demonstrated that the 3D CH scaffold is sufficiently porous to be colonized by primary chondrocytes. Thereby, it provides an optimal environment for the colonization and synthetic activity of chondrocytes during a long culture period where a higher rate of dedifferentiation can be generally observed. Enrichment with hyaluronic acid provides an optimal microenvironment for a more stable maintenance of the chondrocyte phenotype. The use of 3D CH scaffolds causes a further increase in the gene expression of most relevant ECM components when PL is added as a substitute for FBS in the medium. This indicates that the latter system enables a better maintenance of the chondrocyte phenotype, thereby highlighting a fair balance between proliferation and differentiation.

Recent Advances in 3D Printing for Parenteral Applications

3D printing has emerged as an advanced manufacturing technology in the field of pharmaceutical sciences. Despite much focus on enteral applications, there has been a lack of research focused on potential benefits of 3D printing for parenteral applications such as wound dressings, biomedical devices, and regenerative medicines. 3D printing technologies, including fused deposition modeling, vat polymerization, and powder bed printing, allow for rapid prototyping of personalized medications, capable of producing dosage forms with flexible dimensions based on patient anatomy as well as dosage form properties such as porosity. Considerations such as printing properties and material selection play a key role in determining overall printability of the constructs. These parameters also impact drug release kinetics, and mechanical properties of final printed constructs, which play a role in modulating immune response upon insertion in the body. Despite challenges in sterilization of printed constructs, additional post-printing processing procedures, and lack of regulatory guidance, 3D printing will continue to evolve to meet the needs of developing effective, personalized medicines for parenteral applications.

Fabrication of Three-Dimensional Bioactive Composite Scaffolds for Hemostasis and Wound Healing

Fabrication of 3D composite scaffolds was carried out by lyophilization of variable concentrations of collagen and chitosan gel solutions. Fibrinogen and thrombin aerosol were deposited over the surface of scaffolds to enhance hemostasis and wound healing. Composite scaffolds were characterized using differential scanning calorimetry, thermogravimetric analysis, and Fourier-transform infrared spectrophotometer to ascertain the aerosol deposition and stability. Scanning electron microscope showed multilayered porosity with pore size of ~30 μm and mushroom-like fibril growth of aerosol. A detailed investigation by surface plasmon resonance confirmed higher binding affinity of collagen toward the human blood platelets and erythrocytes in comparison to chitosan and was found to increase with the increase in blood cell concentration from 480.8 to 886.4 RU for erythrocytes. Scaffolds showed higher binding response for platelets than erythrocytes, while fibrinogen and thrombin showed no or limited interaction. Highest blood sorption of 83 ± 4% was observed in case of aerosol deposited scaffolds. Aerosol deposited scaffolds showed minimum clotting time of 20 ± 3 s and bleeding time of 38 ± 4 s, which was significantly lower compared to the scaffolds without aerosol treatment. Aerosol deposited composite scaffolds with 2:1 concentration of chitosan/collagen showed complete wound contraction by day 14, while 50% was observed in case of the control group. In vivo studies revealed that chitosan had a crucial role in the inflammatory phase, while collagen played an important role in the proliferation and maturation phase. The present study suggests that the fabricated 3D composite scaffolds with bioactive moieties may be a potential candidate for enhanced hemostasis and wound healing applications.

Comparative Analysis of Collagen and Chitosan-based Dressing for Haemostatic and Wound Healing Application

Collagen and chitosan have haemostatic, tissue fix and wound healing properties but the poor mechanical property limits their application. Therefore, various concentrations of collagen (1-6%) and chitosan (1-2%) were used to develop biopolymer-coated gauzes, with and without glycerol as plasticiser. Glycerol-treated gauzes showed desired mechanical and adhesive property in comparison to polymer-coated gauzes alone. Developed gauzes were characterized using differential scanning calorimetry, thermal gravimetric analysis and Fourier transform infrared spectrophotometry to confirm the biopolymer coating and stability. Scanning electron microscopy showed multilayer coating of the biopolymer and faster clotting in chitosan gauzes in comparison to collagen. Surface plasmon resonance assay confirmed that chitosan exhibited more binding affinity of 65 RU in comparison to collagen, which showed 55 RU with erythrocytes. Decrease in the value of plateletcrit and mean platelet volume confirmed platelet adhesion and aggregation over the surface of polymer-coated dressings. Gamma scintigraphy studies showed 85 ± 2% formulation retention up to 12 h at the wound site in comparison to 40 ± 3% retention of the radiopharmaceutical alone. Collagen and chitosan-coated gauze showed 226 ± 15 s and 179 ± 12 s haemostasis time, respectively, which was significantly less from 506 ± 15 s in standard gauze. Chitosan gauze showed faster wound healing in comparison to the collagen-coated gauze. Chitosan and collagen-coated gauzes showed 55 ± 4% wound contraction on day seven in comparison to 25 ± 2% in the control group, while chitosan gauzes showed complete wound contraction on day fourteenth, while the collagen-coated gauze showed 90 ± 3% on the same day.

Characterization of Orodispersible Films: An Overview of Methods and Introduction to a New Disintegration Test Apparatus Using LDR - LED Sensors

Orodispersible Film (ODF) is a promising and progressive dosage form that offers exceptional drug delivery benefits to patients. Indeed, they are the most transformational alternatives to traditional/conventional dosage forms such as tablets and capsules. ODFs are portable and highly comfortable for self-administration by patients with swallowing problems. The key to gain end-user acceptance is to have an ODF with outstanding quality. Poor quality may lead to choking or spitting, accordingly leading to a lack of compliance. It is vital to employ suitable experimental methodologies that facilitate characterization or determination of the quality of ODF. Nonetheless, there are no standard techniques prescribed in official compendia of any country. But, there is a consensus in the thin-film research community about the characterization techniques that one relies on deciding the quality of an ODF. We review various experimental techniques and highlight its importance in determining the performance and quality of an ODF. We provide a relatively novel and inventive disintegration test apparatus, which works using 'Light Dependent Resistor (LDR) and Light Emitting Diode (LED) sensors' for clear and accurate determination of start and end disintegration time of an ODF.

Construction and Biocompatibility of Three-Dimensional Composite Polyurethane Scaffolds in Liquid Crystal State

Liquid crystal (LC), a characteristic substance of biofilms, has been reported to positively affect cell affinity. To better combine and utilize the properties of an LC and the advantages of polyurethane (PU) elastomers, the three-dimensional printing (3DP) molding technology and the simple soaking-swelling blending technology were used to construct PU/LC 3D composite scaffolds, and the compressive strength, porosity, hydrophilicity, and in vitro cell experiments of the scaffolds were initially discussed. The results indicated that the newly developed PU/LC 3D composite scaffolds exhibited an LC state; the addition of an LC did not change the porosity after swelling while maintaining a high porosity; the compressive strength of the composite scaffolds decreased while still maintaining high mechanical properties and enhancing hydrophilicity. At the same time, it could improve the cell affinity on the surface of the material, which was beneficial to increase the cell adhesion rate and cell activity, promote the osteogenic differentiation of human mesenchymal stem cells grown on the materials, and improve the alkaline phosphatase activity, calcium nodules, and the expression of related osteogenic genes and proteins. These results demonstrated potential applications of PU/LC composite scaffolds in repairing or regeneration of bone tissue engineering.

Functional Fibronectin Adsorption on Aptamer-Doped Chitosan Modulates Cell Morphology by Integrin-Mediated Pathway

A decisive step in cell-biomaterial interaction is represented by the adsorption of proteins at the interface, whose fine control may be useful to trigger proper cell response. To this purpose, we can selectively control protein adsorption on biomaterials by means of aptamers. Aptamers selected to recognize fibronectin dramatically enhance chitosan ability to promote cell proliferation and adhesion, but the underlying biological mechanism remains unknown. We supposed that aptamers contributed to ameliorate the adsorption of fibronectin in an advantageous geometrical conformation for cells, thus regulating their morphology by the proper activation of the integrin-mediated pathway. We investigated this possibility by culturing epithelial cells on chitosan enriched with increasing doses of aptamers in the presence or in the absence of cytoskeleton pharmacological inhibitors. Our results showed that aptamers control cell morphology in a dose dependent manner (p < 0.0001). Simultaneously, when the inhibition of actin polymerization was induced, the control of cell morphology was attenuated (p < 0.0001), while no differences were detected when cells contractility was challenged (p > 0.05). Altogether, our data provide evidence that aptamers contribute to control fibronectin adsorption on biomaterials by preserving its conformation and thus function. Furthermore, our work provides a new insight into a new way to accurately tailor material surface bioactivity.

Study of 3D-printed chitosan scaffold features after different post-printing gelation processes

3D biomaterial manufacturing strategies show an extraordinary driving force for the development of innovative therapies in the tissue engineering field. Here, the behaviour of 3D printed chitosan (CH)-based scaffolds was explored as a function of the post-printing gelation process. To this purpose, gel forming properties of different media were tested on their capability to retain 3D structure, water content, mechanical resistance and surface/internal porosity. Three different gelation media (i.e. KOH 1.5 M, Na₂CO₃ 1.5 M, ammonia vapours) were selected and the 3D CH scaffolds were tested in terms of biocompatibility toward fibroblast as skin associated human cell line.

3D-printed chitosan-based scaffolds: An in vitro study of human skin cell growth and an in-vivo wound healing evaluation in experimental diabetes in rats

The fabrication of porous 3D printed chitosan (CH) scaffolds for skin tissue regeneration and their behavior in terms of biocompatibility, cytocompatibility and toxicity toward human fibroblasts (Nhdf) and keratinocytes (HaCaT), are presented and discussed. 3D cell cultures achieved after 20 and 35 days of incubation showed significant in vitro qualitative and quantitative cell growth as measured by neutral red staining and MTT assays and confirmed by scanning electron microphotographs. The best cell growth was obtained after 35 days on 3D scaffolds when the Nhdf and HaCaT cells, seeded together, filled the pores in the scaffolds. An early skin-like layer consisting of a mass of fibroblast and keratinocyte cells growing together was observed. The tests of 3D printed scaffolds in wound healing carried out on streptozotocin-induced diabetic rats demonstrate that 3D printed scaffolds improve the quality of the restored tissue with respect to both commercial patch and spontaneous healing.

HDPE/Chitosan Blends Modified with Organobentonite Synthesized with Quaternary Ammonium Salt Impregnated Chitosan

In this study, blends based on a high density polyethylene (HDPE) and chitosan (CS) were successfully prepared by melt processing, in a laboratory internal mixer. The CS biopolymer content effect (up to maximum of 40%), and, the addition of bentonite clay modified with quaternary ammonium salt (CTAB) impregnated chitosan as a compatibilizing agent, on the properties of the blends was analyzed by Fourier transform-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile strength, and scanning electron microscopy (SEM). The use of clay modified with CTAB impregnated chitosan, employing a method developed here, improved the compatibility of HDPE with chitosan, and therefore the thermal and some of the mechanical properties were enhanced, making HDPE/chitosan blends suitable candidates for food packaging. It was possible to obtain products of synthetic polymer, HDPE, with natural polymer, chitosan, using a method very used industrially, with acceptable and more friendly properties to the environment, when compared to conventional synthetic polymers. In addition, due to the possibility of impregnated chitosan with quaternary ammonium salt exhibit higher antibacterial activity than neat chitosan, the HDPE/chitosan/organobentonite blends may be potentially applied in food containers to favor the preservation of food for a longer time in comparison to conventional materials.

Anti-fibronectin aptamers improve the colonization of chitosan films modified with D-(+) Raffinose by murine osteoblastic cells

The aim of the present study was to investigate how the enrichment of chitosan films with anti-fibronectin aptamers could enhance scaffold colonization by osteoblasts, by improving their adhesion and accelerating their proliferation. Chitosan discs were enriched with excess of anti-fibronectin aptamer. Aptamer adsorption on chitosan was monitored by measuring aptamer concentration in the supernatant by spectrophotometry, as well as its release, while functionalization was confirmed by labelling aptamers with a DNA intercalating dye. Chitosan samples were then characterized morphologically with atomic force microscopy and physically with contact angle measurement. Chitosan enrichment with fibronectin was then investigated by immunofluorescence and Bradford assay. 2% chitosan discs were then enriched with increasing doses of aptamers and used as culture substrates for MC3T3-E1 cells. Cell growth was monitored by optical microscopy, while cell viability and metabolic activity were assessed by chemiluminescence and by Resazurin Sodium Salt assay. Cell morphology was investigated by cytofluorescence and by scanning electron microscopy. Chitosan films efficiently bound and retained aptamers. Aptamers did not affect the amount of adsorbed fibronectin, but affected osteoblasts behavior. Cell growth was proportional to the amount of aptamer used for the functionalization, as well as aptamers influenced cell morphology and their adhesion to the substrate. Our results demonstrate that the enrichment of chitosan films with aptamers could selectively improve osteoblasts behavior. Furthermore, our results support further investigation of this type of functionalization as a suitable modification to ameliorate the biocompatibility of biomaterial for hard tissue engineering applications.

Highly defined 3D printed chitosan scaffolds featuring improved cell growth

The augmented demand for medical devices devoted to tissue regeneration and possessing a controlled micro-architecture means there is a need for industrial scale-up in the production of hydrogels. A new 3D printing technique was applied to the automation of a freeze-gelation method for the preparation of chitosan scaffolds with controlled porosity. For this aim, a dedicated 3D printer was built in-house: a preliminary effort has been necessary to explore the printing parameter space to optimize the printing results in terms of geometry, tolerances and mechanical properties of the product. Analysed parameters included viscosity of the starting chitosan solution, which was measured with a Brookfield viscometer, and temperature of deposition, which was determined by filming the process with a cryocooled sensor thermal camera. Optimized parameters were applied to the production of scaffolds from solutions of chitosan alone or with the addition of raffinose as a viscosity modifier. Resulting hydrogels were characterized in terms of morphology and porosity. In vitro cell culture studies comparing 3D printed scaffolds with their homologous produced by solution casting evidenced an improvement in biocompatibility deriving from the production technique as well as from the solid state modification of chitosan stemming from the addition of the viscosity modifier.

The in vitro biocompatibility of d-(+) raffinose modified chitosan: Two-dimensional and three-dimensional systems for culturing of horse articular chondrocytes

The present study investigated the biocompatibility of chitosan films and scaffolds modified with d-(+)raffinose and their capability to support the growth and maintenance of the differentiation of articular chondrocytes in vitro. Primary equine articular chondrocytes were cultured on films and scaffolds of modified d-(+) raffinose chitosan. Their behavior was compared to that of chondrocytes grown in conventional bi- and three-dimensional culture systems, such as micromasses and alginate beads. Chitosan films maintained the phenotype of differentiated chondrocytes (typical round morphology) and sustained the synthesis of cartilaginous extracellular matrix (ECM), even at 4weeks of culture. Indeed, starting from 2weeks of culture, chondrocytes seeded on chitosan scaffolds were able to penetrate the surface pores and to colonize the internal matrix. Moreover they produced ECM expressing the genes of typical chondrocytes differentiation markers such as collagen II and aggrecan. In conclusion, chitosan modified with d-raffinose represents an ideal support for chondrocyte adhesion, proliferation and for the maintenance of cellular phenotypic and genotypic differentiation. This novel biomaterial could potentially be a reliable support for the re-differentiation of dedifferentiated chondrocytes.

Haemostatic chitosan coated gauze: in vitro interaction with human blood and in-vivo effectiveness

Background

Chitosan and its derivates are widely used for biomedical application due to antioxidative, anti-inflammatory, antimicrobial and tissue repair induced properties. Chitosan-based materials also used as a haemostatic agent but influence of different molecular weight and concentration of chitosan on biological response of blood cells is still not clear.

The aim of this research was to evaluate interaction between human blood cells and various forms of chitosan-based materials with different molecular weight and chitosan concentration and prove their effectiveness on in-vivo model.

Methods

We used chitosan with molecular weight 200, 500 and 700 kDa and deacetylation rate 80-82 %. For chitosan impregnation of gauze chitosan solutions in 1 % acetic acid with different concentrations (1, 2, 3, 5 %) were used. We used scanning electron microscopy to obtain information about chitosan distribution on cotton surface; Erythrocyte agglutination test and Complete blood count test – for evaluation of interaction between blood cells and chitosan-based materials with different compound. In-vivo studies was performed in 20 Wistar rats to evaluate effectiveness of new dressing.

Results

Our data shown that chitosan can bind erythrocytes in concentration-depend manner that does not depend on its molecular weight. In addition, chitosan-based materials affect selectively human blood cells. Composition of chitosan with cotton materials does not change erythrocyte shape and does not cause agglutination.

Conclusions

Сotton-chitosan materials have higher adhesive properties to platelets that depend on molecular weight and concentration of chitosan. These materials also change platelets’ shape that probable is one of the most important mechanisms of haemostatic effect. In-vivo studies have shown high effectiveness of 2 % 200 kDa chitosan for stop bleeding from arteries of large diameter.

Chitosan-based scaffold modified with D-(+) raffinose for cartilage repair: an in vivo study

BACKGROUND

Osteochondral defects significantly affect patients' quality of life and represent challenging tissue lesions, because of the poor regenerative capacity of cartilage. Tissue engineering has long sought to promote cartilage repair, by employing artificial scaffolds to enhance cell capacity to deposit new cartilage. An ideal biomaterial should closely mimic the natural environment of the tissue, to promote scaffold colonization, cell differentiation and the maintenance of a differentiated cellular phenotype. The present study evaluated chitosan scaffolds enriched with D-(+) raffinose in osteochondral defects in rabbits. Cartilage defects were created in distal femurs, both on the condyle and on the trochlea, and were left untreated or received a chitosan scaffold. The animals were sacrificed after 2 or 4 weeks, and samples were analysed microscopically.

RESULTS

The retrieved implants were surrounded by a fibrous capsule and contained a noticeable inflammatory infiltrate. No hyaline cartilage was formed in the defects. Although defect closure reached approximately 100% in the control group after 4 weeks, defects did not completely heal when filled with chitosan. In these samples, the lesion contained granulation tissue at 2 weeks, which was then replaced by fibrous connective tissue by week 4. Noteworthy, chitosan never appeared to be integrated in the surrounding cartilage.

CONCLUSIONS

In conclusion, the present study highlights the limits of D-(+) raffinose-enriched chitosan for cartilage regeneration and offers useful information for further development of this material for tissue repair.

Functional enhancement of chitosan and nanoparticles in cell culture, tissue engineering, and pharmaceutical applications

As a biomaterial, chitosan has been widely used in tissue engineering, wound healing, drug delivery, and other biomedical applications. It can be formulated in a variety of forms, such as powder, film, sphere, gel, and fiber. These features make chitosan an almost ideal biomaterial in cell culture applications, and cell cultures arguably constitute the most practical way to evaluate biocompatibility and biotoxicity. The advantages of cell cultures are that they can be performed under totally controlled environments, allow high throughput functional screening, and are less costly, as compared to other assessment methods. Chitosan can also be modified into multilayer composite by combining with other polymers and moieties to alter the properties of chitosan for particular biomedical applications. This review briefly depicts and discusses applications of chitosan and nanoparticles in cell culture, in particular, the effects of chitosan and nanoparticles on cell adhesion, cell survival, and the underlying molecular mechanisms: both stimulatory and inhibitory influences are discussed. Our aim is to update the current status of how nanoparticles can be utilized to modify the properties of chitosan to advance the art of tissue engineering by using cell cultures.

Mechanical properties of cellulose: chitosan blends for potential use as a coronary artery bypass graft

The development of intimal hyperplasia is the major cause of failure of both autologous saphenous vein and synthetic coronary artery bypass grafts. This is partially due to graft-host vessel compliance mismatch. Cellulose and chitosan (CELL:CHIT) are both biocompatible, nontoxic, and naturally occurring biopolymers that have been used extensively for biomedical applications. Elastic properties of membranes made of CELL:CHIT blends with different ratios between each polymer were determined using uniaxial tests and the ratio that yielded the less stiff membrane was chosen to prepare a small diameter hollow tube. The presence of chitosan had a favorable impact on the elasticity of the membranes, where the CELL:CHIT 5:5 ratio showed the lowest Young's modulus. Small diameter tubular constructs were fabricated using this optimal CELL:CHIT ratio and the compliance was determined on samples with different wall thickness and internal diameter. The compliance of the hollow tube with inner diameter of 4 mm and wall thickness of 1.2 mm was found to be 5.91%/mmHg×10(-2), which is higher than those of Dacron, expanded polytetrafluorethylene, and saphenous vein, but very close to that of human coronary artery. Burst strength tests revealed that the tubes can withstand at least 300 mmHg. Finally, the tubes showed satisfactory cell attachment property when myofibroblast cells adhered and proliferated on the lumen of the samples.

Properties and biocompatibility of chitosan and silk fibroin blend films for application in skin tissue engineering

Chitosan/silk fibroin (CS/SF) blend films were prepared and evaluated for feasibility of using the films as biomaterial for skin tissue engineering application. Fourier transform infrared spectroscopy and differential scanning calorimetry analysis indicated chemical interaction between chitosan and fibroin. Chitosan enhanced β-sheet conformation of fibroin and resulted in shifting of thermal degradation of the films. Flexibility, swelling index, and enzyme degradation were also increased by the chitosan content of the blend films. Biocompatibility of the blend films was determined by cultivation with fibroblast cells. All films showed no cytotoxicity by XTT assay. Fibroblast cells spread on CS/SF films via dendritic extensions, and cell-cell interactions were noted. Cell proliferation on CS/SF films was also demonstrated, and their phenotype was examined by the expression of collagen type I gene. These results showed possibility of using the CS/SF films as a supporting material for further study on skin tissue engineering.