Cellulose nanocrystals-reinforced dual crosslinked double network GelMA/hyaluronic acid injectable nanocomposite cryogels with improved mechanical properties for cartilage tissue regeneration.

Improvement of mechanical properties of injectable tissue engineering scaffolds is a current challenge. The objective of the current study is to produce a highly porous injectable scaffold with improved mechanical properties. For this aim, cellulose nanocrystals-reinforced dual crosslinked porous nanocomposite cryogels were prepared using chemically crosslinked methacrylated gelatin (GelMA) and ionically crosslinked hyaluronic acid (HA) through the cryogelation process. The resulting nanocomposites showed highly porous structures with interconnected porosity (>90%) and mean pore size in the range of 130-296 µm. The prepared nanocomposite containing 3%w/v of GelMA, 20 w/w% of HA, and 1%w/v of CNC showed the highest Young's modulus (10 kPa) and excellent reversibility after 90% compression and could regain its initial shape after injection by a 16-gauge needle in the aqueous media. The in vitro results demonstrated acceptable viability (>90%) and migration of the human chondrocyte cell line (C28/I2), and chondrogenic differentiation of human adipose stem cells. A two-month in vivo assay on a rabbit's ear model confirmed that the regeneration potential of the prepared cryogel is comparable to the natural autologous cartilage graft, suggesting it is a promising alternative for autografts in the treatment of cartilage defects.

Antibacterial aligned nanofibrous chitosan/PVA patch for repairing chronic tympanic membrane perforations.

Chronic tympanic membrane (TM) perforation is a consequence of trauma or chronic otitis media, and these chronic TM perforations often lead to conduction hearing loss. This study focuses on the development of a patch using a combination of chitosan (CS) and polyvinyl alcohol (PVA) as graft material for repairing chronic tympanic membrane (TM) perforations. Aligned nanofibers were created using a specially designed collector (SDC) through the electrospinning method. The scanning electron microscopy (SEM) analysis revealed that the CS/PVA ratio of (15:85) resulted in uniform and bead-free nanofibers. The aligned nanofibers had a diameter of 131.11 ± 28 nm, indicating that the influence of the electrostatic field introduced by the SDC affected not only the nanofiber alignment but also the nanofiber diameter. The nanofiber angles demonstrated effective alignment. This patch is infused with thyme essential oil (TEO) for antibacterial properties. The results showed that its antibacterial property for Pseudomonas aeruginosa bacteria was enhanced in such a way that the diameter of the antibacterial halo increased from zero to 25 mm. Cell viability assays showed >80 % viability. A preclinical case study on six patients demonstrated the biocompatibility and promising potential of the fabricated patch for eardrum repair.

Bioinspired scaffolds based on aligned polyurethane nanofibers mimic tendon and ligament fascicles.

Topographical factors of scaffolds play an important role in regulating cell functions. Although the effects of alignment topography and three-dimensional (3D) configuration of nanofibers as well as surface stiffness on cell behavior have been investigated, there are relatively few reports that attempt to understand the relationship between synergistic effects of these parameters and cell responses. Herein, the influence of biophysical and biomechanical cues of electrospun polyurethane (PU) scaffolds on mesenchymal stem cells (MSCs) activities was evaluated. To this aim, multiscale bundles were developed by rolling up the aligned electrospun mats mimicking the fascicles of tendons/ligaments and other similar tissues. Compared to mats, the 3D bundles not only maintained the desirable topographical features (i.e., fiber diameter, fiber orientation, and pore size), but also boosted tensile strength (∼40 MPa), tensile strain (∼260%), and surface stiffness (∼1.75 MPa). Alignment topography of nanofibers noticeably dictated cell elongation and a uniaxial orientation, resulting in tenogenic commitment of MSCs. MSCs seeded on the bundles expressed higher levels of tenogenic markers compared to mats. Moreover, the biomimetic bundle scaffolds improved synthesis of extracellular matrix components compared to mats. These results suggest that biophysical and biomechanical cues modulate cell-scaffold interactions, providing new insights into hierarchical scaffold design for further studies.

Polysaccharide-based polyampholyte complex formation: Investigating the role of intra-chain interactions.

The difference in inter-chain and intra-chain electrostatic attraction was investigated in polyelectrolyte and polyampholyte electrostatic complex formation. Three polymers with similar backbone molecular structures including chitosan (Ch) polycation, carboxymethyl cellulose (CMCe) polyanion, and carboxymethyl chitosan (CMCh) polyampholyte were used for this purpose. The turbidimetric, water content, and rheological measurements for polyampholyte self-complex showed more dependence on the ionic strength rather than the polyelectrolyte one. The degree of dissociation (α), dissociation constant (pKa), and intrinsic persistence length were calculated by applying the Katchalsky-Lifson model to potentiometric data. We studied the gyration radii as a function of Debye length and observed the polyampholyte chain contractions due to the intra-chain electrostatic attractions, which minimize the entropic gain of the inter-chain complex formation. This is in accordance with the decrease in pKa by αc for CMCh which is the opposite of that for the Ch and CMCe samples. We also found that the polyampholyte has less intrinsic and electrostatic persistence length compared with both polyanion and polycation with similar chain structures indicating the impact of the inter-chain electrostatic interaction on the complex properties. This study deepens our insight about the behavior of CMCh and the nature of difference between CMCh and Ch/CMCe electrostatic complexes.

PCL-based 3D nanofibrous structure with well-designed morphology and enhanced specific surface area for tissue engineering application.

Tissue engineering opens a new horizon for biological tissue replacement applications. Scaffolds, appropriate cells, and signaling induction are the main three determinant parameters in any tissue engineering applications. Designing a suitable scaffold which can mimic the cellular inherent and natural habitation is of great importance for cellular growth and proliferation. Just like a natural extracellular matrix (ECM), scaffolds provide the cells with an environment for performing biological functions. Accordingly, vast surface area and three-dimensional nanofibrous structures are among the pivotal characteristics of functional scaffolds in tissue engineering, and enhancement of their properties is the main purpose of the present research. In our previous study, a patterned structure composed of continuous nanofibers and microparticles was introduced. In this work, a new modification is applied for adjustment of the surface area of an electrospun/electrosprayed scaffold. For this purpose, at predetermined stages during electrospinning/electrospraying, the nitrogen gas is flushed through the mesh holes of the collector in the opposite direction of the jet movement. This method has led to the formation of very thin nanofibrous layers at nitrogen flush intervals by providing a cooling effect of the sweeping nitrogen. As a consequence, a straticulated structure has been fabricated which possesses extremely high surface/volume ratio. The porosity, water absorption, and morphological analysis were conducted on the obtained scaffold. In vitro cytocompatibility assessments as well as histological analysis demonstrated that the fabricated scaffold provides a proper substrate for cellular attachment, proliferation and infiltration. These findings can be advantageous in three-dimensional tissue engineering such as bone tissue engineering applications. Furthermore, according to the advanced microstructure and vast surface area of the fabricated samples, they can be applied in many other applications, such as membrane, filtration, etc.

Efficacy and safety of chitosan-based bio-compatible dressing versus nanosilver (ActicoatTM ) dressing in treatment of recalcitrant diabetic wounds: A randomized clinical trial.

Chitosan has a biocompatible, biodegradable, and nontoxic nature. The effectiveness of Nano-chitosan films in the field of wound healing has been confirmed previously. The aim of this study was to compare the clinical efficacy and safety of two dressings (chitosan and nanosilver dressings) in the treatment of refractory diabetic wounds. A total of 25 eligible patients with chronic diabetic wound were included and randomly assigned to receive chitosan (13 patients) or nanosilver (12 cases) dressing. The dressings were applied on the wounds based on their protocols and patients were visited and examined by an experienced dermatologist every week. The clinical assessments and healing rates were recorded using diabetic-foot-infection (DFI) score at the 2nd, 4th, and 6th weeks during treatment. The study endpoint, safety and tolerability profile were also documented. The patterns of change in total 10-item-DFI wound scores did not differ significantly over time between the two groups. In both groups, the total 10-item-DFI wound score reduced continuously through the course of study. The mean percentage reduction of this score from baseline was 78.1% and 74.1% in the chitosan and nanosilver dressing groups, respectively. Both dressings were well tolerated and there were no adverse events. The relatively small sample size in both groups was the main limitation of the study. Our findings confirmed that chitosan may be safely and effectively used for the treatment of diabetic wounds just like the nanosilver (ActicoatTM ) dressing. Further studies are recommended with more volunteers and a longer follow-up period.

Shape memory injectable cryogel based on carboxymethyl chitosan/gelatin for minimally invasive tissue engineering: In vitro and in vivo assays.

Shape-memory cryogels have drawn attention as an injectable system to minimize the risks associated with surgical implantation in tissue engineering. To achieve shape memory behavior with hydration as an external stimulus, it is necessary to have a porous elastic network. To achieve this, it is crucial to control the crosslinking process at the time of pore formation, especially for natural-based polymers. In this study, a versatile method using a cryogelation method in the presence of chemical and physical crosslinkers is investigated to obtain an injectable super macroporous elastic structure based on a poly(ampholyte) (carboxymethyl chitosan) and a protein (gelatin). Mechanical, swelling, shape memorizing behavior, injectability, and in vitro and in vivo behavior of cryogels were studied. Cryogelation in a subzero temperature led to the formation of scaffolds with interconnected pores of the size of 350 µm which swelled completely after 3 min. Cryogels had crosslink density up to 22% and elastic modulus in the hydrated state up to 0.054 and 1.733 MPa at low and high strains, respectively, and low hysteresis (<30 kPa). Injectability studies confirmed the ability of the cryogels to be injected through a 16G needle. In vitro studies demonstrated good cellular penetration, cell adhesion, and high cell viability (>100%). In vivo studies using mice showed that the body's response was befitting without inflammation and any side effect for the liver and kidneys.

Injectable hydrogels for bone and cartilage tissue engineering: a review.

Tissue engineering, using a combination of living cells, bioactive molecules, and three-dimensional porous scaffolds, is a promising alternative to traditional treatments such as the use of autografts and allografts for bone and cartilage tissue regeneration. Scaffolds, in this combination, can be applied either through surgery by implantation of cell-seeded pre-fabricated scaffolds, or through injection of a solidifying precursor and cell mixture, or as an injectable cell-seeded pre-fabricated scaffold. In situ forming and pre-fabricated injectable scaffolds can be injected directly into the defect site with complex shape and critical size in a minimally invasive manner. Proper and homogeneous distribution of cells, biological factors, and molecular signals in these injectable scaffolds is another advantage over pre-fabricated scaffolds. Due to the importance of injectable scaffolds in tissue engineering, here different types of injectable scaffolds, their design challenges, and applications in bone and cartilage tissue regeneration are reviewed.

Injectable and reversible preformed cryogels based on chemically crosslinked gelatin methacrylate (GelMA) and physically crosslinked hyaluronic acid (HA) for soft tissue engineering.

Hydrogels are a promising choice for soft tissue (cartilage, skin and adipose) engineering and repair. However, lack of interconnected porosity and poor mechanical performance have hindered their application, especially in natural polymer-based hydrogels. Cryogels with the potential to overcome the shortcomings of hydrogels have drawn attention in the last few years. Thus, in this study, highly porous and mechanically robust cryogels based on interpenetrating polymer network (IPN) of gelatin methacrylate (GelMA) and hyaluronic acid (HA) were fabricated for soft tissue engineering application. Cryogels have a constant amount of GelMA (3% wt) with different concentrations of HA (from 5% to 20 % w/w). In fact, crosslinking through cryogelation in subzero temperature facilitates the formation of interconnected pores with 90 % porosity percentage without external progen. On the other hand, high mechanical stability (no failure up to 90 % compression) was achieved due to the cryogelation and chemical crosslinking of GelMA as well as physical crosslinking of HA. Furthermore, the porous and hydrophile nature of the cryogels resulted in shape memory properties under compression, which can reverse to initial shape after retaining the water. Although increasing the HA concentration followed by the density of physical crosslinking boosted the mechanical performance of cryogels under compression, it limited the reversibility properties. Nevertheless, all cryogels with different HA concentrations showed acceptable gel strength and Young's modulus (G-H-20, E = 6kPa) and had appropriate pore size for cell infiltration and nutrient transportation with good cell adhesion and high cell viability (more than 90 %). The unique property of fabricated cryogels that facilitate less invasive delivery makes them a promising alternative for the soft tissue application.

Fabrication of nanocomposite/nanofibrous functionally graded biomimetic scaffolds for osteochondral tissue regeneration.

One of the main challenges in treating osteochondral lesions via tissue engineering approach is providing scaffolds with unique characteristics to mimic the complexity. It has led to application of heterogeneous scaffolds as a potential candidate for engineering of osteochondral tissues, in which graded multilayered-structure should promote bone and cartilage growth. By designing three-dimensional (3D)-nanofibrous scaffolds mimicking the native extracellular matrix's nanoscale structure, cells can grow in controlled conditions and regenerate the damaged tissue. In this study, novel 3D-functionality graded nanofibrous scaffolds composed of five layers based on different compositions containing polycaprolactone(PCL)/gelatin(Gel)/nanohydroxyapatite (nHA) for osteoregeneration and chitosan(Cs)/polyvinylalcohol(PVA) for chondral regeneration are introduced. This scaffold is fabricated by electrospinning technique using spring as collector to create 3D-nanofibrous scaffolds. Fourier-transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, mechanical compression test, porosimetry, and water uptake studies were applied to study each layer's physicochemical properties and whole functionally graded scaffold. Besides, biodegradation and biological studies were done to investigate biological performance of scaffold. Results showed that each layer has a fibrous structure with continuous nanofibers with improved pore size and porosity of novel 3D scaffold (6-13 µm and 90%) compared with two-dimensional (2D) mat (2.2 µm and 19.3%) with higher water uptake capacity (about 100 times of 2D mat). Compression modulus of electrospun scaffold was increased to 78 MPa by adding nHA. The biological studies revealed that the layer designed for osteoregeneration could improve cell proliferation rate in comparison to the layer designed for chondral regeneration. These results showed such structure possesses a promising potential for the treatment of osteochondral defects.

Crosslinking strategies for silk fibroin hydrogels: promising biomedical materials.

Due to their strong biomimetic potential, silk fibroin (SF) hydrogels are impressive candidates for tissue engineering, due to their tunable mechanical properties, biocompatibility, low immunotoxicity, controllable biodegradability, and a remarkable capacity for biomaterial modification and the realization of a specific molecular structure. The fundamental chemical and physical structure of SF allows its structure to be altered using various crosslinking strategies. The established crosslinking methods enable the formation of three-dimensional (3D) networks under physiological conditions. There are different chemical and physical crosslinking mechanisms available for the generation of SF hydrogels (SFHs). These methods, either chemical or physical, change the structure of SF and improve its mechanical stability, although each method has its advantages and disadvantages. While chemical crosslinking agents guarantee the mechanical strength of SFH through the generation of covalent bonds, they could cause some toxicity, and their usage is not compatible with a cell-friendly technology. On the other hand, physical crosslinking approaches have been implemented in the absence of chemical solvents by the induction of ß-sheet conformation in the SF structure. Unfortunately, it is not easy to control the shape and properties of SFHs when using this method. The current review discusses the different crosslinking mechanisms of SFH in detail, in order to support the development of engineered SFHs for biomedical applications.

PEGylated curcumin-loaded nanofibrous mats with controlled burst release through bead knot-on-spring design.

APEGylatedcurcumin (PCU) loaded electrospuns based on poly(ε-caprolactone) (PCL) andpolyvinyl alcohol (PVA) were fabricated for wound dressing applications. The main reason for this wound dressing design is antibacterialactivity enhancement, and wound exudates management. PEGylation increases curcuminsantibacterial properties and PVA can help exudates management. For optimal wound dressing, first, response surface methodology (RSM) was applied to optimize the electrospinning parameters to achieve appropriate nanofibrous mats. Then a three-layer electrospun was designed by considering the water absorbability, PCU release profile as well as antibacterial and biocompatibility of the final wound dressing. The burst release in controlled release systems could be evaluated for prevention of the higher initial drug release and control the effective life time. The PCU release results illustrated that the bead knot plays a positive role in controlling the release profile andby increase in the number of beads per unit area from 3000 to 9000 mm-2,the PCU burst release will be reduced; Also in vitro studies show that optimized three-layer dressing based on PCL/PVA/PCU can support water vapour transmission rate in optimal range and also absorb more than three times exudates in comparison with mono-layerdressing. Antibacterial tests show that the electrospun wound dressing containing 5% PCU exhibits100% antibacterial activityas well as cell viability level within an acceptable range.

Mechanical Characteristics of SPG-178 Hydrogels: Optimizing Viscoelastic Properties through Microrheology and Response Surface Methodology

Background: Self-assembling peptides (SApeptides) have growing applications in tissue engineering and regenerative medicine. The application of SApeptide-based hydrogels depends strongly on their viscoelastic properties. Optimizing the properties is of importance in tuning the characteristics of the hydrogels for a variety of applications. Methods: In this study, we employed statistical modeling, conducted with the response surface methodology (RSM) and particle tracking microrheology, to investigate the effects of self-assembling SPG-178 peptide and added NaCl salt concentrations and milieu type (deionized water or blood serum) on the viscoelastic properties of SPG-178 hydrogels. A central composite RSM model was employed for finding the optimum value of the parameters to achieve the highest storage modulus and the lowest tan δ. Results: Viscoelastic properties of each sample, including storage modulus, loss modulus, and tan δ, were determined. Storage modulus and tan δ were modeled, accounting for the impact of the SPG-178 peptide and NaCl concentrations and milieu type on the viscoelastic properties. It was found that the SPG-178 hydrogel storage modulus was positively influenced by the SPG-178 peptide concentration and the serum. Conclusion: A combination of microrheology and RSM is a useful test method for statistical modeling and analysis of rheological behavior of solid-like gels, which could be applied in various biomedical applications such as hemostasis.

Polyvinyl alcohol/soy protein isolate nanofibrous patch for wound-healing applications.

Soy protein isolate (SPI), due to its biocompatibility, biodegradability, abundance and being inexpensive, is a suitable polymer for medical applications. In this study, electrospun nanofibrous mats (ENMs) and casting films (CFs), comprising polyvinyl alcohol (PVA)/SPI, were prepared and compared. Both crosslinked ENMs and CFs physical, chemical, mechanical, and biological properties were investigated for wound-healing applications. Considering the importance of exudate absorption by wound dressing the uptake test of all samples was performed in simulated exudate solution. The amount of absorbed exudate, water vapor transmission rate, and mechanical elongation for CFs were 69.243% ± 22.7, 266.7 g/m2 day, and 2.0825% and increased to 383.33% ± 105.3, 1332.02 g/m2 day, and 12.292% in the case of ENMs, respectively. There was no significant difference between cell supporting of the two samples due to similar composition and their non-toxic properties. The results showed that ENMs have promising potential in wound-healing applications.

Chitosan-based biocompatible dressing for treatment of recalcitrant lesions of cutaneous leishmaniasis: A pilot clinical study.

BACKGROUND: Chitosan has a biocompatible, biodegradable and nontoxic nature. The effectiveness of nano-chitosan films in the treatment of cutaneous leishmaniasis has been confirmed previously in susceptible laboratory animals. AIMS: The aim of this study is to evaluate the safety and efficacy of a chitosan-based biocompatible dressing in patients with cutaneous leishmaniasis who were either nonresponsive to or had medical contraindications for conventional treatments. MATERIALS AND METHODS: A total of 10 eligible patients were included in this single arm, single center study. The sterile chitosan film was immersed in saline serum and was cautiously extended over the wound to avoid air occlusion. Sterile Vaseline gauze was then applied and the film was kept on the wound site for 7 days and was repeated every week until the healing was completed. Complete clinical response was defined as complete re-epithelialization of the skin lesion as well as microscopic negative results for amastigote forms of Leishmania sp. RESULTS: All patients showed either significant (30%) or complete (70%) improvement after 8 weeks of therapy and at 16 weeks post treatment all cases were completely cured. It was well tolerated and there were no product-related adverse events such as allergic reaction or infection. Moreover, no recurrences were observed in any patients after 6 months follow-up. LIMITATIONS: The lack of a control group, relatively small sample size and failure to evaluate the histological and molecular effects of chitosan were the limitations of this study. CONCLUSION: Our findings confirmed that chitosan can be safely and effectively used for the treatment of cutaneous leishmaniasis. We were unable to find any previous clinical study in evaluating the efficacy of chitosan for cutaneous leishmaniasis on human subjects. Further studies are recommended to design a randomized, double-blinded clinical trial with more volunteers who infected with different species of Leishmania and various clinical forms of cutaneous leishmaniasis.

3D in vitro cancerous tumor models: Using 3D printers.

Recently, magnetic Hyperthermia is one of the promising methods for cancer treatments. In this method by applying magnetic fields and generating heat, cancerous tissues are eliminated. The degree and pattern of generated heat in cancerous and adjacent non-cancerous tissues plays an important role on the outcome of the treatment. it is mainly affected by diffusion and distribution pattern of magnetic nanoparticles within the cancerous and non-cancerous tissues. Study the diffusion and distribution patterns of magnetic nanoparticle in vivo is difficult and costly in many cases and in some cases evaluating the amount of generated heat at cancer site is almost impossible. In vitro models for cancer tissues are alternatives for in vivo models. However, usual in vitro models could not resembling all the characteristics of a cancer tumor. In this hypothesis we propose that using 3D printers can provide a platform to fabricate a personalized in vitro cancer model which could simulate the most important features of the cancerous tissues (including shape and vascular network) and can be used to study magnetic hyperthermia in a simulated media of compatible to in vivo conditions.

Graphene oxide containing chitosan scaffolds for cartilage tissue engineering.

Enhancement of physical and mechanical properties of the scaffolds is achieved via various methods including cross-linking and incorporation of nano particles. In the present research chitosan-based scaffolds firstly were reinforced with the incorporation of the graphene oxide (GO) nanoparticles. The GO nanoparticles were synthesized from graphite successfully and were identified by TGA, XRD, SEM and FTIR analytical methods. Nanocomposite scaffolds based on chitosan with different percentages of the GO were prepared. The chitosan-GO nanocomposite scaffolds were then simultaneously sterilized and cross-linked in an autoclave and comprehensively characterized. In XRD measurements, the absence of the peak at 10° related to GO, is evidence that the GO layers are exfoliated. With increasing the GO concentration from 0 to 0.1, 0.2 and 0.3%, physical and mechanical properties were improved, considerably. Seeding of the human articular chondrocytes on the nanocomposite scaffolds showed an increased proliferation with augmentation of the GO percentage particularly in prolonged cultivation periods (14 days). Investigation of the human articular chondrocyte morphology revealed a more spherical morphology of the cells on the cross-linked scaffolds for 21 days of culture in vitro.

On the analysis of microrheological responses of self-assembling RADA16-I peptide hydrogel.

This work aims to obtain a hydrogel based on self-assembling RADA16-I with proper rheological properties for hemostasis application. Response surface methodology (RSM) was performed to predict the gelation and stiffness of the hydrogel in different concentrations of peptide and NaCl in water and blood serum milieus. Particle tracking microrheology technique was used to evaluate Brownian motion of polystyrene particles in the peptide solutions to obtain their trajectories and measure the viscoelastic properties (G'', G″, and tan δ). Formation of gel was influenced by the concentrations of peptide and salt and their interactions. Optimum response for maximizing elastic modulus was obtained in the presence of blood serum in comparison with water. Negative effect of excess amount of NaCl was predicted by RSM model and confirmed by animal study. Circular dichroism (CD) analysis showed formation of ß-sheet secondary structure in water. On the other hand, in the presence of blood serum, tertiary structure was formed. Dimensional characterization of peptide fibers was performed by means of AFM. Peptide self-assembly in blood serum (pH around 7) which contains different ions, led to enhancing bonds between fibers, caused increasing the fiber diameter and length by 20 and 10 times, respectively. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 330-338, 2019.

Enhanced cellular response elicited by addition of amniotic fluid to alginate hydrogel-electrospun silk fibroin fibers for potential wound dressing application.

This study aimed to evaluate a novel bioactive wound dressing from alginate hydrogel-electrospun silk fibroin (SF) fibers with the ability to deliver amniotic fluid (AF) to the wound site. AF is highly enriched with multiple therapeutic agents that can promote cellular response and wound healing. In this study, electrospun SF fibers were first fabricated by electrospinning method and then combined with the alginate hydrogel (ALG) containing AF. Different dressings were made by changing the alginate to AF ratio. The scanning electron microscopy images revealed that SF fibers were fully covered with alginate hydrogel. In addition, the modulus of the dressing decreased by lowering ALG/AF ratios, while a reverse trend was observed for the elongation-at-break. In vitro AF release profiles indicated that an increase in the concentration of ALG leads to a reduction in the AF amount. Fibroblast culturing on the fabricated dressings demonstrated that cellular proliferation, spreading, and secretion of collagen enhanced with increasing AF. Taken together, our results provide a novel bioactive dressing with great potentials for speeding up the healing process in severe wounds.

Chitosan/polyethylene glycol fumarate blend films for wound dressing application: in vitro biocompatibility and biodegradability assays.

Blending is one of the effective approaches in preparing tailored materials with a wide range of properties. Thus, chitosan-based polymers have been fabricated and used as wound dressings since they possess better properties than those of the constituent materials. The objective of this work was to evaluate the biocompatibility and biodegradability of biodegradable blend films based on polyethylene glycol-co-fumarate (PEGF) and chitosan (Ch). The blend films of Ch/PEGF were prepared by solution casting/solvent evaporation method. Degradation behavior of these blend films was evaluated in a simulated fluid at physiological pH supplemented with lysozyme at a concentration similar to that in human serum by weight loss of the films and changes in the pH of media. When the pH of incubation media was analyzed, with an increase of PEGF content in the blend films, the degradation rate increased accordingly. The pH of the media of samples was not significantly changed at any measured time point and all films kept their integrities during 28 days. The biocompatibility of the films and cell behavior on the surface of these films were investigated by in vitro tests. Biological assessment using mouse fibroblast cell line L929 on the blend films of Ch/PEGF indicated that films supported the attachment, spreading and proliferation of cells. Since the Ch/PEGF films are biocompatible with the tailored biodegradation rate, they might have a great prospective position in the application of wound dressings.