Electrospun anti-adhesion barrier made of chitosan alginate for reducing peritoneal adhesions

Multi-functional dual-layer nanofibrous membrane for prevention of postoperative pancreatic leakage

Postoperative pancreatic leakage due to pancreatitis in patients is a life-threatening surgical complication. The majority of commercial barriers are unable to meet the demands for pancreatic leakage due to poor adhesiveness, toxicity, and inability to degrade. In this study, we fabricated mitomycin-c and thrombin-loaded multifunctional dual-layer nanofibrous membrane with a combination of alginate, PCL, and gelatin to resolve the leakage due to suture line disruption, promote hemostasis, wound healing, and prevent postoperative tissue adhesion. Electrospinning was used to fabricate the dual-layer system. The study results demonstrated that high gelatin and alginate content in the inner layer decreased the fiber diameter and water contact angle, and crosslinking allowed the membrane to be more hydrophilic, making it highly biodegradable, and adhering firmly to the tissue surfaces. The results of in vitro biocompatibility and hemostatic assay revealed that the dual-layer had a higher cell proliferation and showed effective hemostatic properties. Moreover, the in vivo studies and in silico molecular simulation indicated that the dual layer was covered at the wound site, prevented suture disruption and leakage, inhibited hemorrhage, and reduced postoperative tissue adhesion. Finally, the study results proved that dual-layer multifunctional nanofibrous membrane has a promising therapeutic potential in preventing postoperative pancreatic leakage.

Current issues and potential solutions for the electrospinning of major polysaccharides and proteins: A review

Biopolymers, especially polysaccharides and proteins, are the promising green replacement for petroleum based polymers. Due to their innate properties, they are effectively used in biomedical applications, especially tissue engineering, wound healing, and drug delivery. The fibrous morphology of biopolymers is essentially required for the effectiveness in these biomedical applications. Electrospinning (ES) is the most advanced and robust method to fabricate nanofibers (NFs) and provides a complete solution to the conventional methods issues. However, the major issues regarding fabricating polysaccharides and protein nanofibers using ES include poor electrospinnability, lack of desired fundamental properties for a specific application by a single biopolymer, and insolubility among common solvents. The current review provides the main strategies for effective electrospinning of the major biopolymers. The key strategies include blending major biopolymers with suitable biopolymers and optimizing the solvent system. A systematic literature review was done to provide the optimized solvent system of the major biopolymers along with their best possible biopolymeric blend for ES. The review also highlights the fundamental issues with the commercialization of ES based biomedical products and provides future directions to improve the fabrication of biopolymeric nanofibers.

Balance of antiperitoneal adhesion, hemostasis, and operability of compressed bilayer ultrapure alginate sponges

In surgery, both antiperitoneal adhesion barriers and hemostats with high efficiency and excellent handling are necessary. However, antiadhesion and hemostasis have been examined separately. In this study, six different ultrapure alginate bilayer sponges with thicknesses of 10, 50, 100, 200, 300, and 500 μm were fabricated via lyophilization and subsequent mechanical compression. Compression significantly enhanced mechanical strength and improved handling. Furthermore, it had a complex effect on dissolution time and contact angle. Therefore, the 100 μm compressed sponge showed the highest hemostatic activity in the liver bleeding model in mice, whereas the 200 μm sponge demonstrated the highest antiadhesion efficacy among the compressed sponges in a Pean crush hepatectomy-induced adhesion model in rats. For the first time, we systematically evaluated the effect of sponge compression on foldability, fluid absorption, mechanical strength, hemostatic effect, and antiadhesion properties. The optimum thickness of an alginate bilayer sponge by compression balances antiperitoneal adhesion and hemostasis simultaneously.

Marine Biopolymers as Bioactive Functional Ingredients of Electrospun Nanofibrous Scaffolds for Biomedical Applications

Marine biopolymers, abundantly present in seaweeds and marine animals, feature diverse structures and functionalities, and possess a wide range of beneficial biological activities. Characterized by high biocompatibility and biodegradability, as well as unique physicochemical properties, marine biopolymers are attracting a constantly increasing interest for the development of advanced systems for applications in the biomedical field. The development of electrospinning offers an innovative technological platform for the production of nonwoven nanofibrous scaffolds with increased surface area, high encapsulation efficacy, intrinsic interconnectivity, and structural analogy to the natural extracellular matrix. Marine biopolymer-based electrospun nanofibrous scaffolds with multifunctional characteristics and tunable mechanical properties now attract significant attention for biomedical applications, such as tissue engineering, drug delivery, and wound healing. The present review, covering the literature up to the end of 2021, highlights the advancements in the development of marine biopolymer-based electrospun nanofibers for their utilization as cell proliferation scaffolds, bioadhesives, release modifiers, and wound dressings.

Ibuprofen-Loaded Electrospun PCL/PEG Nanofibrous Membranes for Preventing Postoperative Abdominal Adhesion

Electrospun nanofibrous membranes are a widely used physical barrier for reducing postoperative adhesion. However, these physical barriers could not prevent adhesion formation completely. Because a high-intensity inflammation occurs in the surgical area, the presence of relevant drugs to control such an inflammation is desperately needed. In this study, we fabricated an electrospun composite ibuprofen-loaded poly(ethylene glycol) (PEG)/polycaprolactone (PCL) nanofibrous membrane (NFM) to prevent abdominal adhesions. This membrane aimed to act as a barrier between the abdominal wall and surrounding tissues, without interrupting mass transfer and normal wound healing. Among various fabricated composite NFMs, PCL/25PEG-6% NFMs showed the lowest fiber diameter (448.8 ± 124.4 nm), the smallest pore size (<2 μm), and moderate ultimate stress and strain. The PCL/25PEG-6% NFMs had the lowest water contact angle (≈75°) and the highest drug profile release (≈80%) within 14 days. Furthermore, in vitro toxicity examination of PCL/25PEG-6% toward fibroblast cells demonstrated a cell viability of ≈82% after 3 days, proving its prolonged antiadhesion ability. In addition, the low number of adherent cells with a rounded shape and low cell proliferation on these NFMs indicated their special antiadhesive effects. Collectively, these results indicated that the PCL/25PEG-6% membrane might be a suitable barrier to prevent abdominal adhesion.

BMP-2 Enhances Osteogenic Differentiation of Human Adipose-Derived and Dental Pulp Stem Cells in 2D and 3D In Vitro Models

Bone tissue provides support and protection to different organs and tissues. Aging and different diseases can cause a decrease in the rate of bone regeneration or incomplete healing; thus, tissue-engineered substitutes can be an acceptable alternative to traditional therapies. In the present work, we have developed an in vitro osteogenic differentiation model based on mesenchymal stem cells (MSCs), to first analyse the influence of the culture media and the origin of the cells on the efficiency of this process and secondly to extrapolate it to a 3D environment to evaluate its possible application in bone regeneration therapies. Two osteogenic culture media were used (one commercial from Stemcell Technologies and a second supplemented with dexamethasone, ascorbic acid, glycerol-2-phosphate, and BMP-2), with human cells of a mesenchymal phenotype from two different origins: adipose tissue (hADSCs) and dental pulp (hDPSCs). The expression of osteogenic markers in 2D cultures was evaluated in several culture periods by means of the immunofluorescence technique and real-time gene expression analysis, taking as reference MG-63 cells of osteogenic origin. The same strategy was extrapolated to a 3D environment of polylactic acid (PLA), with a 3% alginate hydrogel. The expression of osteogenic markers was detected in both hADSCs and hDPSCs, cultured in either 2D or 3D environments. However, the osteogenic differentiation of MSCs was obtained based on the culture medium and the cell origin used, since higher osteogenic marker levels were found when hADSCs were cultured with medium supplemented with BMP-2. Furthermore, the 3D culture used was suitable for cell survival and osteogenic induction.

Nanodiamond-chitosan functionalized hernia mesh for biocompatibility and antimicrobial activity

Polypropylene (PP) mesh is most commonly used for the treatment of hernia and pelvic floor construction. However, some of the patients have a few complications after surgery due to the rejection or infection of the implanted meshes. The poor biocompatibility of PP mesh, low wettability results in poor cell attachment/proliferation and restricts the loading of antibacterial agent, leading to a slow healing process and high risk of infection after surgery. Here in this study, a new technique has been employed to develop a novel antimicrobial and biocompatible PP mesh modified with bioactive chitosan and functionalized nanodiamond (FND) for infection inhibition and acceleration of the healing process. An oxygen plasma treatment PP mesh was used then chitosan was strongly attached to the surface of the PP fibers. Subsequently, FND as an antibacterial agent was loaded into the chitosan modified PP fiber to provide desired antibacterial functions. The meshes were characterised with XRD, FTIR, SEM, EDX, water contact angle, confocal, and optical microscopy. The modified PP mesh with chitosan and FND showed a significant increase in its hydrophilicity and L929 fibroblast cell attachment. Furthermore, the modified mesh exhibited great antibacterial efficiency against Escherichia coli. Therefore, the newly developed technique to modify PP mesh could be a promising technique to generate a biocompatible PP mesh to accelerate the healing process and reduce the risk of infection after surgery.

Chitosan-based blends for biomedical applications

Polysaccharides are the most abundant naturally available carbohydrate polymers; composed of monosaccharide units covalently connected together. Chitosan is the most widely used polysaccharides because of its exceptional biocompatibility, mucoadhesion, and chemical versatility. However, it suffers from a few drawbacks, e.g. poor mechanical properties and antibacterial activity for biomedical applications. Blending chitosan with natural or synthetic polymers may not merely improve its physicochemical and mechanical properties, but may also improve its bioactivity-induced properties. This review paper summarizes progress in chitosan blends with biodegradable polymers and polysaccharides and their biomedical applications. Blends of chitosan with alginate, starch, cellulose, pectin and dextran and their applications were particularly addressed. The critical and challenging aspects as well as the future ahead of the use of chitosan-based blends were eventually enlightened.

A review: progress in preventing tissue adhesions from a biomaterial perspective

Postoperative adhesions (POA) are one of the main problems suffered by patients and are a common complaint. It is considered to be closely associated with the healing mechanism of damaged tissues. Tissue adhesions accompany other symptoms such as inflammation, pain, and even dyskinesia under certain conditions, compromising the patients' quality of life. On the other hand, common treatments involve high costs, re-surgery or long-term hospital stays. Therefore, alternative approaches need to be formulated so that aforementioned problems can be resolved. To this end, a review of recent advances in this context is imperative. In this review, we have highlighted the mechanism of adhesion formation, advances in common therapeutic approaches, and prospective treatments in preventing tissue adhesions. Based on the literature, it can be determined that the disadvantages of available commercial products in the treatment of tissue adhesion have led researchers to utilize alternative methods for designing anti-adhesive products with different structures such as electrospun fibrous mats, hydrogels, and nanospheres. These studies are on the fast track in producing optimal anti-adhesion materials. We hope that this article can attract attention by showing various mechanisms and solutions involved in adhesion problems and inspire the further development of anti-adhesion biomaterials.

Advancement of Biomaterial-Based Postoperative Adhesion Barriers

Postoperative peritoneal adhesion (PPA) is a prevalent incidence that generally happens during the healing process of traumatized tissues. It causes multiple severe complications such as intestinal obstruction, chronic abdominal pain, and female infertility. To prevent PPA, several antiadhesion materials and drug delivery systems composed of biomaterials are used clinically, and clinical antiadhesive is one of the important applications nowadays. In addition to several commercially available materials, like film, spray, injectable hydrogel, powder, or solution type have been energetically studied based on natural and synthetic biomaterials such as alginate, hyaluronan, cellulose, starch, chondroitin sulfate, polyethylene glycol, polylactic acid, etc. Moreover, many kinds of animal adhesion models, such as cecum abrasion models and unitary horn models, are developed to evaluate new materials' efficacy. A new animal adhesion model based on hepatectomy and conventional animal adhesion models is recently developed and a new adhesion barrier by this new model is also developed. In summary, many kinds of materials and animal models are studied; thus, it is quite important to overview this field's current progress. Here, PPA is reviewed in terms of the species of biomaterials and animal models and several problems to be solved to develop better antiadhesion materials in the future are discussed.

Electrospun Nanofibrous Membranes for Preventing Tendon Adhesion

Tendon injuries are frequent, and surgical interventions toward their treatment might result in significant clinical complications. Pretendinous adhesion results in the disruption of the normal gliding mechanism of a damaged tendon, painful movements, and an increased chance of rerupture in the future. To alleviate postsurgical tendon-sheath adhesions, many investigations have been directed toward the development of repair approaches using electrospun nanofiber scaffolds. Such methods mainly take advantage of nanofibrous membranes (NFMs) as physical barriers to prevent or minimize adhesion of a repaired tendon to its surrounding sheath. In addition, these nanofibers can also locally deliver antiadhesion and anti-inflammatory agents to reduce the risk of tendon adhesion. This article reviews recent advances in the design, fabrication, and characterization of nanofibrous membranes developed to serve as (i) biomimetic tendon sheaths and (ii) physical barriers. Various features of the membranes are discussed to present insights for further development of repair methods suitable for clinical practice.

Dual-functional anti-adhesion barrier prepared using micro-hierarchical structured and neutralized shellac films for drug release

Micro-hierarchical structured shellac films were prepared using a solution casting method with dodecyltrichloro-immobilized shellac microparticles. We evaluated two opposite surfaces of the shellac films-one a micro-hierarchical structured side and the other a neutralized shellac side using alkali ethanol-for their applications in the medical field. A bending strength test using a tensile strength testing machine and measurement of surface hardness using a scratch hardness tester indicated that the optimal composition of the base films comprised 15% shellac and 10% calcium phosphate as durability promoting agents. Further, dodecyltrichloro-immobilized shellac microparticles were synthesized and spray-deposited on the films. The solubility of shellac increased as the pH of the shellac solution increased. Analyses of cell adhesion, proliferation, and anti-thrombus efficiency were performed using a WST assay, field emission scanning electron microscope, and hemocytometer. The contact angle with the micro-hierarchical structure surface was approximately 150°. The spray-deposited shellac film yielded a lower cell and platelet adhesion rate (20%) than the untreated film. These results indicate that the micro-hierarchical structure has unique properties and that this novel superhydrophobic biodegradable shellac film can be applied as a blood/tissue-compatible, biodegradable material for implantable medical devices that need an anti-adhesion barrier.

Biomaterials to Prevent Post-Operative Adhesion

Surgery is performed to treat various diseases. During the process, the surgical site is healed through self-healing after surgery. Post-operative or tissue adhesion caused by unnecessary contact with the surgical site occurs during the normal healing process. In addition, it has been frequently found in patients who have undergone surgery, and severe adhesion can cause chronic pain and various complications. Therefore, anti-adhesion barriers have been developed using multiple biomaterials to prevent post-operative adhesion. Typically, anti-adhesion barriers are manufactured and sold in numerous forms, such as gels, solutions, and films, but there are no products that can completely prevent post-operative adhesion. These products are generally applied over the surgical site to physically block adhesion to other sites (organs). Many studies have recently been conducted to increase the anti-adhesion effects through various strategies. This article reviews recent research trends in anti-adhesion barriers.

Solution Blow Spinning of Polyvinylidene Fluoride Based Fibers for Energy Harvesting Applications: A Review

Polyvinylidene fluoride (PVDF)-based piezoelectric materials (PEMs) have found extensive applications in energy harvesting which are being extended consistently to diverse fields requiring strenuous service conditions. Hence, there is a pressing need to mass produce PVDF-based PEMs with the highest possible energy harvesting ability under a given set of conditions. To achieve high yield and efficiency, solution blow spinning (SBS) technique is attracting a lot of interest due to its operational simplicity and high throughput. SBS is arguably still in its infancy when the objective is to mass produce high efficiency PVDF-based PEMs. Therefore, a deeper understanding of the critical parameters regarding design and processing of SBS is essential. The key objective of this review is to critically analyze the key aspects of SBS to produce high efficiency PVDF-based PEMs. As piezoelectric properties of neat PVDF are not intrinsically much significant, various additives are commonly incorporated to enhance its piezoelectricity. Therefore, PVDF-based copolymers and nanocomposites are also included in this review. We discuss both theoretical and experimental results regarding SBS process parameters such as solvents, dissolution methods, feed rate, viscosity, air pressure and velocity, and nozzle design. Morphological features and mechanical properties of PVDF-based nanofibers were also discussed and important applications have been presented. For completeness, key findings from electrospinning were also included. At the end, some insights are given to better direct the efforts in the field of PVDF-based PEMs using SBS technique.

Electrospun Alginate Nanofibers Toward Various Applications: A Review

Alginate has been a material of choice for a spectrum of applications, ranging from metal adsorption to wound dressing. Electrospinning has added a new dimension to polymeric materials, including alginate, which can be processed to their nanosize levels in order to afford unique nanostructured materials with fascinating properties. The resulting nanostructured materials often feature high porosity, stability, permeability, and a large surface-to-volume ratio. In the present review, recent trends on electrospun alginate nanofibers from over the past 10 years toward advanced applications are discussed. The application of electrospun alginate nanofibers in various fields such as bioremediation, scaffolds for skin tissue engineering, drug delivery, and sensors are also elucidated.

Cross-linked cartilage acellular matrix film decreases postsurgical peritendinous adhesions

Cartilage extracellular matrix contains antiadhesive and antiangiogenic molecules such as chondromodulin-1, thrombospondin-1, and endostatin. We have aimed to develop a cross-linked cartilage acellular matrix (CAM) barrier for peritendinous adhesion prevention. CAM film was fabricated using decellularized porcine cartilage tissue powder and chemical cross-linking. Biochemical analysis of the film showed retention of collagen and glycosaminoglycans after the fabrication process. Physical characterization of the film showed denser collagen microstructure, increased water contact angle, and higher tensile strength after cross-linking. The degradation time in vivo was 14 d after cross-linking. The film extract and film surface showed similar cell proliferation, while inhibiting cell migration and cell adhesion compared to standard media and culture plate, respectively. Application of the film after repair resulted in similar tendon healing and significantly less peritendinous adhesions in a rabbit Achilles tendon injury model compared to repair only group, demonstrated by histology, ultrasonography, and biomechanical testing. In conclusion, the current study developed a CAM film having biological properties of antiadhesion, together with biomechanical properties and degradation profile suitable for prevention of peritendinous adhesions.

Fabrication and Characterisation of Stimuli Responsive Piezoelectric PVDF and Hydroxyapatite-Filled PVDF Fibrous Membranes

Poly(vinylidene fluoride) has attracted interest from the biomaterials community owing to its stimuli responsive piezoelectric property and promising results for application in the field of tissue engineering. Here, solution blow spinning and electrospinning were employed to fabricate PVDF fibres and the variation in resultant fibre properties assessed. The proportion of piezoelectric β-phase in the solution blow spun fibres was higher than electrospun fibres. Fibre production rate was circa three times higher for solution blow spinning compared to electrospinning for the conditions explored. However, the solution blow spinning method resulted in higher fibre variability between fabricated batches. Fibrous membranes are capable of generating different cellular response depending on fibre diameter. For this reason, electrospun fibres with micron and sub-micron diameters were fabricated, along with successful inclusion of hydroxyapatite particles to fabricate stimuli responsive bioactive fibres.

Electrospun Water-Borne Polyurethane Nanofibrous Membrane as a Barrier for Preventing Postoperative Peritendinous Adhesion

Peritendinous adhesion is a major complication after tendon injury and the subsequent repairs or reconstructions. The degree of adhesion can be reduced by the interposition of a membranous barrier between the traumatized tendon and the surrounding tissue. In the present study, electrospun water-borne polyurethane (WPU) nanofibrous membranes (NFMs) were created for use after the reparation or reconstruction of tendons to reduce adhesion. In the electrospinning process, water was employed as the solvent for WPU, and this solvent was ecofriendly and nontoxic. The nanofibrous architecture and pore size of the WPU NFMs were analyzed. Their microporosity (0.78⁻1.05 µm) blocked the penetration of fibroblasts, which could result in adhesion and scarring around the tendon during healing. The release of WPU mimicked the lubrication effect of the synovial fluid produced by the synovium around the tendon. In vitro cell studies revealed that the WPU NFMs effectively reduced the number of fibroblasts that became attached and that there was no significant cytotoxicity. In vivo studies with the rabbit flexor tendon repair model revealed that WPU NFMs reduced the degree of peritendinous adhesion, as determined using a gross examination; a histological cross section evaluation; and measurements of the range of motion of interphalangeal joints (97.1 ± 14.7 and 79.0 ± 12.4 degrees in proximal and distal interphalangeal joints respectively), of the length of tendon excursion (11.6 ± 1.9 cm), and of the biomechanical properties.

Structural Investigation of a Self-Cross-Linked Chitosan/Alginate Dialdehyde Multilayered Film with in Situ QCM-D and Spectroscopic Ellipsometry

A chitosan/alginate dialdehyde multilayered film was fabricated using the layer-by-layer assembly method. Besides electrostatic interaction that promotes alternate adsorption of the oppositely charged polyelectrolytes, the Schiff base reaction between the amine groups on chitosan and the aldehyde groups on alginate dialdehyde provides a covalently cross-linked film, which after reduction by sodium cyanoborohydride is stable under both acidic and alkaline conditions. Moreover, the cross-linked film is responsive to changes in pH and addition of multivalent salts. The structural properties of the multilayered film such as thickness, refractive index, and water content were examined using simultaneous quartz crystal microbalance with dissipation monitoring and spectroscopic ellipsometry.

Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields

The prospective uses of tree gum polysaccharides and their nanostructures in various aspects of food, water, energy, biotechnology, environment and medicine industries, have garnered a great deal of attention recently. In addition to extensive applications of tree gums in food, there are substantial non-food applications of these commercial gums, which have gained widespread attention due to their availability, structural diversity and remarkable properties as 'green' bio-based renewable materials. Tree gums are obtainable as natural polysaccharides from various tree genera possessing exceptional properties, including their renewable, biocompatible, biodegradable, and non-toxic nature and their ability to undergo easy chemical modifications. This review focuses on non-food applications of several important commercially available gums (arabic, karaya, tragacanth, ghatti and kondagogu) for the greener synthesis and stabilization of metal/metal oxide NPs, production of electrospun fibers, environmental bioremediation, bio-catalysis, biosensors, coordination complexes of metal-hydrogels, and for antimicrobial and biomedical applications. Furthermore, polysaccharides acquired from botanical, seaweed, animal, and microbial origins are briefly compared with the characteristics of tree gum exudates.

Transglutaminase-catalyzed preparation of crosslinked carboxymethyl chitosan/carboxymethyl cellulose/collagen composite membrane for postsurgical peritoneal adhesion prevention

Peritoneal adhesion is a general complication following pelvic and abdominal surgery, which may lead to chronic abdominal pain, bowel obstruction, organ injury, and female infertility. Biodegradable polymer membranes have been suggested as physical barriers to prevent peritoneum adhesion. In this work, a transglutaminase (TGase)-catalyzed crosslinked carboxymethyl chitosan/carboxymethyl cellulose/collagen (CMCS/CMCL/COL) composite anti-adhesion membrane with various proportions of CMCS, CMCL, and COL (40/40/20, 35/35/30, 25/25/50) was developed. After crosslinking by TGase, the composite anti-adhesion membranes shown enhanced mechanical properties and improved biodegradability. Meanwhile, the high cytocompatibility of anti-adhesion membranes was proved by in vitro cell culture study. Moreover, the anti-adhesion membrane with the proportion of 25/25/50 was implanted between the artificially defected cecum and peritoneal wall in rats and following by general observation, histological examination, and inflammatory factors assay. The results indicated that the anti-adhesion membrane can significantly prevent peritoneal adhesion with negligible immunogenicity. Therefore, the composite membrane crosslinked by TGase had satisfactory anti-adhesive effects with high biocompatibility and low antigenicity, which could be used as a preventive barrier for peritoneal adhesion.

Encapsulation of Bioactive Compound in Electrospun Fibers and Its Potential Application

Electrospinning is a simple and versatile encapsulation technology. Since electrospinning does not involve severe conditions of temperature or pressure or the use of harsh chemicals, it has great potential for effectively entrapping and delivering bioactive compounds. Recently, electrospinning has been used in the food industry to encapsulate bioactive compounds into different biopolymers (carbohydrates and proteins), protecting them from adverse environmental conditions, maintaining the health-promoting properties, and achieving their controlled release. Electrospinning opens a new horizon in food technology with possible commercialization in the near future. This review summarizes the principles and the types of electrospinning processes. The electrospinning of biopolymers and their application in encapsulating of bioactive compounds are highlighted. The existing scope, limitations, and future prospects of electrospinning bioactive compounds are also presented.

Evaluation of a series of silk fibroin protein-based nonwoven mats for use as an anti-adhesion patch for wound management in robotic surgery

A novel anti-adhesion nonwoven mat mainly composed of silk fibroin protein (SFP) was fabricated via the single-spinneret electrospinning technique. A series of SFP-based electrospun nonwoven mats containing additives of different synthetic polymer ratios, such as pure SFP, SFP/poly(vinyl alcohol) (PVA), SFP/polyethylene glycol (PEG), and SFP/polyethylene oxide (PEO) were produced and compared. All membranes were porous and had diameters of 324.02 ± 113.7, 308.86 ± 74.02, 366.22 ± 115.81, and 341.82 ± 119.42 nm, respectively. The average pore size for each membrane was 1.132 ± 0.99, 0.811 ± 0.424, 0.975 ± 0.741, and 0.784 ± 0.497 μm² . No nonwoven mats showed significant cytotoxicity toward fibroblast cells based on the results of MTT assays. Surprisingly, for all groups of SFP-based nonwoven mats, nitrate formation was reduced by up to 94.55 ± 14.50%, 92.16 ± 19.38%, 91.28 ± 28.375%, and 92.00 ± 12.64% in lipopolysaccharide-induced RAW 264.7 macrophages model. Tissue anti-adhesion potential was evaluated in an in vitro fibroblast cell adhesion model and in vivo wounded mice model. In vitro, the mean cell anti-adhesion percentage of fibroblast cells changed over time in the following order: PVA/SFP > SFP > PEG/SFP∼PEO/SFP. In vivo, SFP and PVA/SFP-treated groups both showed superior collagen regeneration and wound closure. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 221-230, 2018.

Preparation and characterization of polycaprolactone–polyethylene glycol methyl ether and polycaprolactone–chitosan electrospun mats potential for vascular tissue engineering

Recently, natural polymers are frequently comingled with synthetic polymers either by physical or chemical modification to prepare numerous tissue-engineered graft with promising biological function, strength, and stability. The aim of this study was to determine the efficiency for vascular tissue engineering of two distinctly different mats, one that comprised polycaprolactone–polyethylene glycol methyl ether and other that comprised polycaprolactone–chitosan. Nano/microfibrous mats prepared from electro-spinning were characterized for fiber diameter, porosity, wettability, and mechanical strength. Biological efficacy on both biodegradable mats was assessed by rat bone marrow mesenchymal stem cells, and polycaprolactone–polyethylene glycol methyl ether showed feasibility for use as an inner layer by inducing endothelial-specific gene expression and polycaprolactone–chitosan as an outer layer on dual layered without sacrificing tensile strength, small-diameter blood vessels. Therefore, scaffolds fabricated from this research could be potential sources for tissue-engineered vascular graft and could also overcome the well-known drawbacks, such as thrombogenicity and stenosis, in managing vascular disease.

Injectable thermosensitive hydrogel containing hyaluronic acid and chitosan as a barrier for prevention of postoperative peritoneal adhesion

Peritoneal adhesion is one of the common complications after abdominal surgery. Injectable thermosensitive hydrogel could serve as an ideal barrier to prevent this postoperative tissue adhesion. In this study, poly(N-isopropylacrylamide) (PNIPAm) was grafted to chitosan (CS) and the polymer was further conjugated with hyaluronic acid (HA) to form thermosensitive HA-CS-PNIPAm hydrogel. Aqueous solutions of PNIPAm and HA-CS-PNIPAm at 10%(w/v) are both free-flowing and injectable at room temperature and exhibit sol-gel phase transition around 31°C; however, HA-CS-PNIPAm shows less volume shrinkage after gelation and higher complex modulus than PNIPAm. Cell culture studies indicate both injectable hydrogel show barrier effects to reduce fibroblasts penetration while induce little cytotoxicity in vitro. From a sidewall defect-bowel abrasion model in rats, significant reduction of postoperative peritoneal adhesion was found for peritoneal defects treated with HA-CS-PNIPAm compared with those treated with PNIPAm and untreated controls from gross and histological evaluation. Furthermore, HA-CS-PNIPAm did not interfere with normal peritoneal tissue healing and did not elicit acute toxicity from blood analysis and tissue biopsy examination. By taking advantage of the easy handling and placement properties of HA-CS-PNIPAm during application, this copolymer hydrogel would be a potentially ideal injectable anti-adhesion barrier after abdominal surgeries.

Prevention of postoperative adhesions by biodegradable cryogels from pectin and chitosan polysaccharides

The main complication that may arise after surgery is the formation of adhesions. The current trend in the prevention of postoperative adhesions is the application of anti-adhesive barrier materials for the separation of wound tissue during the critical period of mesothelial repair and healing. In this work, cryogels based on pectin and chitosan were obtained by the ionic cryotropic gelation method. It was found that the Heracleum L. pectin cryogels are more elastic (73 ± 6 kPa) than the apple pectin cryogels (29 ± 11 kPa). The addition of chitosan with different physical and chemical characteristics did not significantly affect the elasticity of pectin–chitosan cryogels. The greatest swelling ability was achieved during in vivo incubation of Heracleum L. pectin cryogels and Heracleum L. pectin with reacetylated chitosan cryogels (17.1 ± 1.6 and 14.2 ± 2.0 g/g, respectively). It was found that the complete biodegradation of apple pectin cryogels occurred within 24 h of incubation in the rat abdominal cavity. Heracleum L. pectin cryogels were encapsulated in a fibrous capsule and detected in the abdominal cavity after 168 h. Maximum anti-adhesion effect was observed through the use of apple pectin cryogels (0 ± 0.5 score). Significant anti-adhesive effect was also observed through the use of apple pectin–reacetylated chitosan cryogels (1 ± 0.5 score). Due to the high anti-adhesive activity, such cryogels can be recommended for the development of a new barrier material for use in surgery. The potential anti-adhesive mechanism of apple pectin cryogels which may be attributed to a combination of barrier function and bioactivity of cryogels components was discussed.

Prevention of peritendinous adhesions with electrospun chitosan-grafted polycaprolactone nanofibrous membranes

As one of the common complications after tendon injury and subsequent surgery, peritendinous adhesions could be minimized by directly placing a physical barrier between the injured site and the surrounding tissue. With the aim of solving the shortcomings of current biodegradable anti-adhesion barrier membranes, we propose the use of an electrospun chitosan-grafted polycaprolactone (PCL-g-CS) nanofibrous membrane (NFM) to prevent peritendinous adhesions. After introducing carboxyl groups on the surface by oxygen plasma treatment, the polycaprolactone (PCL) NFM was covalently grafted with chitosan (CS) molecules, with carbodiimide as the coupling agent. Compared with PCL NFM, PCL-g-CS NFM showed a similar fiber diameter, permeation coefficient for bovine serum albumin, ultimate tensile strain, reduced pore diameter, lower water contact angle, increased water sorption and tensile strength. With its submicrometer pore diameter (0.6-0.9μm), both NFMs could allow the diffusion of nutrients and waste while blocking fibroblast penetration to prevent adhesion formation after tendon surgery. Cell culture experiments verified that PCL-g-CS NFM can reduce fibroblast attachment while maintaining the biocompatibility of PCL NFM, implicating a synergistic anti-adhesion effect to raise the anti-adhesion efficacy. In vivo studies with a rabbit flexor digitorum profundus tendon surgery model confirmed that PCL-g-CS NFM effectively reduced peritendinous adhesion from gross observation, histology, joint flexion angle, gliding excursion and biomechanical evaluation. An injured tendon wrapped with PCL-g-CS NFM showed the same tensile strength as the naturally healed tendon, indicating that the anti-adhesion NFM will not compromise tendon healing.

The role of hybrid chitosan membranes on scarring process following lumbar surgery: post-laminectomy experimental model

OBJECTIVES

Post-operative scarring process on lumbar surgery is object of several studies mainly because of the epidural fibrosis formation. Hybrid chitosan have shown promising effect on fibrosis prevention. The aim of this study was to determine the influence of chitosan-silane membrane on the lumbar surgery scarring process. These membranes have improved mechanical strength which makes them suitable to maintain a predefined shape.

METHODS

A two level lumbar laminectomy was performed in 14 New Zealand male rabbits. Laminectomy sites were randomly selected for biomaterial or control. Chitosan membranes were prepared and care was taken in order to make it adapted to the bone defect dimensions covering the totality of the defect including the bone margins. Histological analysis was performed by haematoxylin/eosin and by Masson's trichrome staining four weeks after laminectomy.

RESULTS

Microscope observations revealed the presence of a well-organized regenerating tissue, integrated in the surrounding vertebral bone tissue with a regular and all-site interface on the chitosan sites, in clear contrast with the presence of a disorganized regenerating tissue with aspects consistent with the persistence of a chronic inflammatory condition, on control sites.

DISCUSSION

The results of this study clearly demonstrated that hybrid chitosan had an organizing effect on post-operative scarring process. The presence of the hybrid chitosan membrane resulted on a well-organized tissue integrated in the surrounding vertebral bone tissue with signs of regenerative bone tissue in continuity with native bone. This can be a major feature on the dynamics of epidural fibrosis formation.

In vitro and in vivo cytocompatibility of electrospun nanofiber scaffolds for tissue engineering applications

An electrospun polymeric-based nanofibrous scaffold mimicking the extracellular matrix and serving as a temporary support for cell growth, adhesion, migration and proliferation.

Molecular weight-modulated electrospun poly(ε-caprolactone) membranes for postoperative adhesion prevention

Electrospun PCL membranes with various molecular weights behave distinctively for the prevention of surgery induced-adhesions, which finally helped acquire well-suited candidates for anti-adhesion biomaterial films.