Effects of an Acetic Acid and Acetone Mixture on the Characteristics and Scaffold–Cell Interaction of Electrospun Polycaprolactone Membranes

The Impacts of the Sterilization Method and the Electrospinning Conditions of Nanofibrous Biodegradable Layers on Their Degradation and Hemocompatibility Behavior

The use of electrospun polymeric biodegradable materials for medical applications is becoming increasingly widespread. One of the most important parameters regarding the functionality of nanofiber scaffolds during implantation and the subsequent regeneration of damaged tissues concerns their stability and degradation behavior, both of which are influenced by a wide range of factors (the properties of the polymer and the polymer solution, the technological processing approach, the sterilization method, etc.). This study monitored the degradation of nanofibrous materials fabricated from degradable polyesters as a result of the sterilization method applied (ethylene oxide and gamma irradiation) and the solvent system used to prepare the spun polymer solution. Aliphatic polyesters PCL and PLCL were chosen for this study and selected with respect to the applicability and handling in the surgical setting of these nanofibrous materials for vascular bandaging. The results revealed that the choice of solvent system exerts a significant impact on degradation during sterilization, especially at higher gamma irradiation values. The subsequent enzyme-catalyzed degradation of the materials following sterilization indicated that the choice of the sterilization method influenced the degradation behavior of the materials. Whereas wave-like degradation was evident concerning ethylene oxide sterilization, no such behavior was observed following gamma-irradiation sterilization. With concern for some of the tested materials, the results also indicated the potential for influencing the development of degradation within the bulk versus degradation from the surface of the material. Both the sterilization method and the choice of the spinning solvent system were found to impact degradation, which was observed to be most accelerated in the case of PLCL (L-lactide-co-caprolactone copolymer) electrospun from organic acids and subsequently sterilized using gamma irradiation. Since we planned to use these materials in cardiovascular applications, it was decided that their hemocompatibility would also be tested. The results of these tests revealed that changes in the structures of the materials initiated by sterilization may exert thrombogenic and anticoagulant impacts. Moreover, the microscopic analysis suggested that the solvent system used in the preparation of the materials potentially affects the behavior of erythrocytes; however, no indication of the occurrence of hemolysis was detected.

Electrospinning and electrospun polysaccharide-based nanofiber membranes: A review

The electrospinning technology has set off a tide and given rise to the attention of a widespread range of research territories, benefiting from the enhancement of nanofibers which made a spurt of progress. Nanofibers, continuously produced via electrospinning technology, have greater specific surface area and higher porosity and play a non-substitutable key role in many fields. Combined with the degradability and compatibility of the natural structure characteristics of polysaccharides, electrospun polysaccharide nanofiber membranes gradually infiltrate into the life field to help filter air contamination particles and water pollutants, treat wounds, keep food fresh, monitor electronic equipment, etc., thus improving the life quality. Compared with the evaluation of polysaccharide-based nanofiber membranes in a specific field, this paper comprehensively summarized the existing electrospinning technology and focused on the latest research progress about the application of polysaccharide-based nanofiber in different fields, represented by starch, chitosan, and cellulose. Finally, the benefits and defects of electrospun are discussed in brief, and the prospects for broadening the application of polysaccharide nanofiber membranes are presented for the glorious expectation dedicated to the progress of the eras.

Evaluation of polycaprolactone nanofibers' spinnability using green solvent systems by solution blow spinning (SBS)

Solution blow spinning (SBS) is a promising alternative to produce fibrous matrices for a wide range of applications, such as packaging and biomedical devices. Polycaprolactone (PCL) is a biodegradable polyester commonly used for spinning. The usual choices for producing PCL solutions include chlorinated solvents (CS), such as chloroform. However, the high toxicity of CS makes it difficult for biological and green applications. This work evaluates the influence of two less toxic solvents, acetic acid (AA) and acetone (Acet), and their mixtures (AA/Acet) on the properties of PCL fibers produced by SBS. The results showed that Acet does not cause degradation of the PCL chains, in opposition to AA. Furthermore, adding acetone to the acetic acid tended to preserve the size of PCL chains. It was not possible to produce fibers using PCL in 100% acetone. However, the AA/Acet mixture allowed the efficient production of PCL fibers. The proportion of Acet and AA in the mixture modulated the fiber morphology and orientation, making it possible to use this green solvent system according to the desired application.

Optimization of Oligomer Chitosan/Polyvinylpyrrolidone Coating for Enhancing Antibacterial, Hemostatic Effects and Biocompatibility of Nanofibrous Wound Dressing

A synergistic multilayer membrane design is necessary to satisfy a multitude of requirements of an ideal wound dressing. In this study, trilayer dressings with asymmetric wettability, composed of electrospun polycaprolactone (PCL) base membranes coated with oligomer chitosan (COS) in various concentrations of polyvinylpyrrolidone (PVP), are fabricated for wound dressing application. The membranes are expected to synergize the hygroscopic, antibacterial, hemostatic, and biocompatible properties of PCL and COS. The wound dressing was coated by spraying the solution of 3% COS and 6% PVP on the PCL base membrane (PVP6–3) three times, which shows good interaction with biological subjects, including bacterial strains and blood components. PVP6–3 samples confirm the diameter of inhibition zones of 20.0 ± 2.5 and 17.9 ± 2.5 mm against Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The membrane induces hemostasis with a blood clotting index of 74% after 5 min of contact. In the mice model, wounds treated with PVP6–3 closed 95% of the area after 10 days. Histological study determines the progression of skin regeneration with the construction of granulation tissue, new vascular systems, and hair follicles. Furthermore, the newly-growth skin shares structural resemblances to that of native tissue. This study suggests a simple approach to a multi-purpose wound dressing for clinical treatment.

Three-dimensional-printed polycaprolactone/polypyrrole conducting scaffolds for differentiation of human olfactory ecto-mesenchymal stem cells into Schwann cell-like phenotypes and promotion of neurite outgrowth

Implantation of a suitable nerve guide conduit (NGC) seeded with sufficient Schwann cells (SCs) is required to improve peripheral nerve regeneration efficiently. Given the limitations of isolating and culturing SCs, using various sources of stem cells, including mesenchymal stem cells (MSCs) obtained from nasal olfactory mucosa, can be desirable. Olfactory ecto-MSCs (OE-MSCs) are a new population of neural crest-derived stem cells that can proliferate and differentiate into SCs and can be considered a promising autologous alternative to produce SCs. Regardless, a biomimetic physicochemical microenvironment in NGC such as electroconductive substrate can affect the fate of transplanted stem cells, including differentiation toward SCs and nerve regeneration. Therefore, in this study, the effect of 3D printed polycaprolactone (PCL)/polypyrrole (PPy) conductive scaffolds on differentiation of human OE-MSCS into functional SC-like phenotypes was investigated. Biological evaluation of 3D printed scaffolds was examined by in vitro culturing the OE-MSCs on samples surfaces, and conductivity showed no effect on increased cell attachment, proliferation rate, viability, and distribution. In contrast, immunocytochemical staining and real-time polymerase chain reaction analysis indicated that 3D structures coated with PPy could provide a favorable microenvironment for OE-MSCs differentiation. In addition, it was found that differentiated OE-MSCs within PCL/PPy could secrete the highest amounts of nerve growth factor and brain-derived neurotrophic factor neurotrophic factors compared to pure PCL and 2D culture. After co-culturing with PC12 cells, a significant increase in neurite outgrowth on PCL/PPy conductive scaffold seeded with differentiated OE-MSCs. These findings indicated that 3D printed PCL/PPy conductive scaffold could support differentiation of OE-MSCs into SC-like phenotypes to promote neurite outgrowth, suggesting their potential for neural tissue engineering applications.

Etched 3D-Printed Polycaprolactone Constructs Functionalized with Reduced Graphene Oxide for Enhanced Attachment of Dental Pulp-Derived Stem Cells

A core challenge in the field of tissue engineering is the ability to establish pipeline workflows for the design and characterization of scaffold technologies with clinically translatable attributes. The parallel development of biomaterials and stem cell populations represents a self-sufficient and streamlined approach for establishing such a pipeline. In the current study, rat dental pulp stem cell (rDPSC) populations were established to assess functionalized polycaprolactone (PCL) constructs. Initial optimization and characterization of rDPSC extraction and culture conditions confirmed that cell populations were readily expandable and demonstrated surface markers associated with multi-potency. Subset populations were transduced to express DsRed fluorescent protein as a mechanism of tracking both cells and cell-derived extracellular matrix content on complex scaffold architecture. Thermoplastic constructs included reduced graphene oxide (rGO) as an additive to promote cellular attachment and were further modified by surface etching a weak acetic acid solution to roughen surface topographical features, which was observed to dramatically improve cell surface coverage in vitro. Based on these data, the modified rGO-functionalized PCL constructs represent a versatile platform for bone tissue engineering, capable of being applied as a standalone matrix or in conjunction with bio-active payloads such as DPSCs or other bio-inks.

The Efficacy of Silver-Based Electrospun Antimicrobial Dressing in Accelerating the Regeneration of Partial Thickness Burn Wounds Using a Porcine Model

(1) Background: Wounds with damages to the subcutaneous are difficult to regenerate because of the tissue damages and complications such as bacterial infection. (2) Methods: In this study, we created burn wounds on pigs and investigated the efficacy of three biomaterials: polycaprolactone-gelatin-silver membrane (PCLGelAg) and two commercial burn dressings, Aquacel^® Ag and UrgoTul^TM silver sulfadiazine. In vitro long-term antibacterial property and in vivo wound healing performance were investigated. Agar diffusion assays were employed to evaluate bacterial inhibition at different time intervals. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assays were used to compare antibacterial strength among samples. Second-degree burn wounds in the pig model were designed to evaluate the efficiency of all dressings in supporting the wound healing process. (3) Results: The results showed that PCLGelAg membrane was the most effective in killing both Gram-positive and Gram-negative bacteria bacteria with the lowest MBC value. All three dressings (PCLGelAg, Aquacel, and UrgoTul) exhibited bactericidal effect during the first 24 h, supported wound healing as well as prevented infection and inflammation. (4) Conclusions: The results suggest that the PCLGelAg membrane is a practical solution for the treatment of severe burn injury and other infection-related skin complications.

Comparing the wound healing effect of a controlled release wound dressing containing curcumin/ciprofloxacin and simvastatin/ciprofloxacin in a rat model: A preclinical study

Inflammation and infection are two main factors predisposing a wound to become a chronic one. Degradable wound dressings involving the controlled release of suitable drugs at the ulcer site are one of the solutions to make wounds healing progress smoothly and rapidly. In this research, biodegradable dressings made of polyglycerol sebacate/polycaprolactone (PGS/PCL) containing curcumin/ciprofloxacin (CUR/CIP) and simvastatin/ciprofloxacin (SIM/CIP) were prepared by using the coaxial electrospinning method. Transmission electron microscopy for uniform core/shell structure, swelling ratio, and drug release pattern of the wound dressings were evaluated. At the in vivo study, histometric, histopathologic, and collagen expression study was performed. The PGS/PCL samples containing SIM/CIP showed a burst release pattern of CIP with a delay in the release of SIM; meanwhile, in the samples containing CUR/CIP, both drugs showed a burst release behavior. No cytotoxicity response was observed in the study groups. The in vivo study showed that wound closure was almost completed only in the SIM/CIP group after 14 days. After 14 days, in the wound treated with SIM/CIP dressing, the amount of collagen deposition and angiogenesis was higher than that of the others. These results clearly showed the effect of SIM/CIP on the improvement of the wound healing efficiency in the long term (14 days) and the effect of CUR/CIP on wound contraction in the short term (4 day). It seems, therefore, that the use of SIM and CUR simultaneously in a wound dressing could cause a synergistic effect in the wound repair.

Characterizations and Antibacterial Efficacy of Chitosan Oligomers Synthesized by Microwave-Assisted Hydrogen Peroxide Oxidative Depolymerization Method for Infectious Wound Applications

The use of naturally occurring materials with antibacterial properties has gained a great interest in infected wound management. Despite being an abundant resource in Vietnam, chitosan and its derivatives have not yet been intensively explored for their potential in such application. Here, we utilized a local chitosan source to synthesize chitosan oligomers (OCS) using hydrogen peroxide (H2O2) oxidation under the microwave irradiation method. The effects of H2O2 concentration on the physicochemical properties of OCS were investigated through molecular weight, degree of deacetylation, and heavy metal contamination for optimization of OCS formulation. Then, the antibacterial inhibition was examined; the minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC) of OCS-based materials were determined against common skin-inhabitant pathogens. The results show that the local Vietnamese chitosan and its derivative OCS possessed high-yield purification while the molecular weight of OCS was inversely proportional and proportional to the concentration of H2O2, respectively. Further, the MIC and MBC of OCS ranged from 3.75 to less than 15 mg/mL and 7.5-15 mg/mL, respectively. Thus, OCS-based materials induce excellent antimicrobial properties and can be attractive for wound dressings and require further investigation.

Investigating the effect of multi-coated hydrogel layer on characteristics of electrospun PCL membrane coated with gelatin/silver nanoparticles for wound dressing application

In this study, the effect of coated hydrogel layer on characteristics of the whole gelatin/silver nanoparticles multi-coated polycaprolactone membrane (PCLGelAg) was investigated through systematic and typical wound dressing characterizations to select the optimal number of layers for practical applications. Scanning electron microscopy, free swell absorptive capacity and tensile test in both wet and dry conditions were conducted to characterize all fabricated membranes of six coating times. In vitro cytotoxicity and agar diffusion evaluation were also carried out to assess the biocompatibility and antibacterial activity of the membranes. The findings illustrated that as the coated layers increase, the absorptive capacity, and degradation rate were higher, the membranes were stiffer in dry state while the tensile strength in wet state, elongation, and cell viability were significantly decreased. PCLGelAg3 was chosen to be the best fit for wound healing since it maintained quite sufficient maximum buffer uptake, elasticity, cell viability along with inducing abnormalities in bacterial morphology and preventing biofilm formation.

Development of biodegradable webs of PLA/PCL blends prepared via electrospinning: Morphological, chemical, and thermal characterization

Biodegradable polymers have a mean role to mimic native tissues and allow cells to penetrate, grow, and proliferate with their advanced features in tissue engineering applications. The physiological, chemical, mechanical, and biological qualities of the surfaces, which are presented from biodegradable polymers, affect the final properties of the scaffolds. In this study, it is aimed to produce fibrous webs by electrospinning method for tissue engineering applications using two different biopolymers, polylactic acid (PLA) and polycaprolactone (PCL). These polymers are used either alone or in a blended form (PLA/PCL, 1/1 wt.). Within the scope of the study, polymer concentrations (6, 8 and 10%) and solvent types (used for chloroform/ethanol/acetic acid mixture, PCL and PLA/PCL mixtures, and chloroform/acetone, PLA) vary as solution parameters. Fibrous webs are investigated in terms of morphological, chemical, and thermal characteristics. Results show continuous fibers are examined for 8 or 10% polymer concentrations with an average fiber diameter of 1.3-2.7 μm and pore area of 4-9 μm² . No fiber formation is observed in sample groups with a polymer concentration of 6% and beaded structures are formed. Water contact angle analysis proves the hydrophobic properties of PLA and PCL, whereas Fourier-transform infrared results show there is no solution residue on the surfaces, so there is no toxic effect. Also, in differential scanning calorimetry analysis, the characteristic crystallization peaks of the polymers are recognized, and when the polymers are in a blend, it beholds that they have effects on each other's crystallization.

Multilayer Alginate-Polycaprolactone Electrospun Membranes as Skin Wound Patches with Drug Delivery Abilities

A multilayer nanofibrous membrane consisting of a layer of polycaprolactone and one of physically cross-linked alginate-embedding ZnO nanoparticles is prepared via electrospinning technique as potential wound healing patches with drug delivery capabilities. A washing-cross-linking protocol is developed to obtain stable materials at the same time removing poly(ethylene oxide), which was used here as a cospinning agent for alginate, without interfering with the membrane's peculiar nanofibrous structure. The mechanical behavior of the samples is assessed via a uniaxial tensile test showing appropriate resistance and manageability together with a good thermal stability as proved via thermogravimetric analysis. The polycaprolactone external layer enriches the samples with good liquid-repellent properties, whereas the alginate layer is able to promote tissue regeneration owing to its capability to promote cell viability and allow exudate removal and gas exchanges. Moreover, using methylene blue and methyl orange as model molecules, promising drug delivery abilities are observed for the mats. Indeed, depending on the nature and on the dye-loading concentration, the release kinetic can be easily tuned to obtain a slow controlled or a fast burst release. Consequently, the proposed alginate-polycaprolactone membrane represents a promising class of innovative, simple, and cost-effective wound healing patches appropriate for large-scale production.

Conjugated Linoleic Acid Grafting Improved Hemocompatibility of the Polycaprolactone Electrospun Membrane

Polycaprolactone (PCL) is a versatile biomaterial with a wide range of medical applications, but its use in blood-contacting devices is hampered due to insufficient hemocompatibility. In this work, electrospun polycaprolactone (PCL) membranes were chemically grafted with conjugated linoleic acid (CLA) to prevent induced blood coagulation. The density of grafted CLA and its effects on the morphology and wettability of the membranes were examined. The study also investigated how the membrane interacted with human whole blood and platelets to determine its antithrombotic properties. As the results suggested, the grafting caused a negligible effect on the physical properties of the membrane but greatly improved its compatibility with blood, showing that the approach can be investigated further for blood-contacting applications.