Electrospun Polycaprolactone Scaffolds Research Articles

Rat liver ECM incorporated into electrospun polycaprolactone scaffolds as a platform for hepatocyte culture.

Liver disease is expanding across the globe; however, health-care systems still lack approved pharmaceutical treatment strategies to mitigate potential liver failures. Organ transplantation is the only treatment for liver failure and with increasing cases of liver disease, transplant programs increasingly cannot provide timely transplant availability for all patients. The development of pharmaceutical mitigation strategies is clearly necessary and methods to improve drug development processes are considered vital for this purpose. Herein, we present a methodology for incorporating whole organ decellularised rat liver ECM (rLECM) into polycaprolactone (PCL) electrospun scaffolds with the aim of producing biologically relevant liver tissue models. rLECM PCL scaffolds have been produced with 5w/w% and 10w/w% rLECM:PCL and were analyzed by SEM imaging, tensile mechanical analyses and FTIR spectroscopy. The hepatocellular carcinoma cell line, HepG2, was cultured upon the scaffolds for 14 days and were analyzed through cell viability assay, DNA quantification, albumin quantification, immunohistochemistry, and RT-qPCR gene expression analysis. Results showed significant increases in proliferative activity of HepG2 on rLECM containing scaffolds alongside maintained key gene expression. This study confirms that rLECM can be utilized to modulate the bioactivity of electrospun PCL scaffolds and has the potential to produce electrospun scaffolds suitable for enhanced hepatocyte cultures and in-vitro liver tissue models.

Functionalized Electrospun Scaffold-Human-Muscle-Derived Stem Cell Construct Promotes In Vivo Neocartilage Formation.

Polycaprolactone (PCL) is a non-cytotoxic, completely biodegradable biomaterial, ideal for cartilage tissue engineering. Despite drawbacks such as low hydrophilicity and lack of functional groups necessary for incorporating growth factors, it provides a proper environment for different cells, including stem cells. In our study, we aimed to improve properties of scaffolds for better cell adherence and cartilage regeneration. Thus, electrospun PCL–scaffolds were functionalized with ozone and loaded with TGF-β3. Together, human-muscle-derived stem cells (hMDSCs) were isolated and assessed for their phenotype and potential to differentiate into specific lineages. Then, hMDSCs were seeded on ozonated (O) and non-ozonated (“naïve” (NO)) scaffolds with or without protein and submitted for in vitro and in vivo experiments. In vitro studies showed that hMDSC and control cells (human chondrocyte) could be tracked for at least 14 days. We observed better proliferation of hMDSCs in O scaffolds compared to NO scaffolds from day 7 to day 28. Protein analysis revealed slightly higher expression of type II collagen (Coll2) on O scaffolds compared to NO on days 21 and 28. We detected more pronounced formation of glycosaminoglycans in the O scaffolds containing TGF-β3 and hMDSC compared to NO and scaffolds without TGF-β3 in in vivo animal experiments. Coll2-positive extracellular matrix was observed within O and NO scaffolds containing TGF-β3 and hMDSC for up to 8 weeks after implantation. These findings suggest that ozone-treated, TGF-β3-loaded scaffold with hMDSC is a promising tool in neocartilage formation.

Evaluation of perfusion-driven cell seeding of small diameter engineered tissue vascular grafts with a custom-designed seed-and-culture bioreactor.

Tissue engineering commonly entails combining autologous cell sources with biocompatible scaffolds for the replacement of damaged tissues in the body. Scaffolds provide functional support while also providing an ideal environment for the growth of new tissues until host integration is complete. To expedite tissue development, cells need to be distributed evenly within the scaffold. For scaffolds with a small diameter tubular geometry, like those used for vascular tissue engineering, seeding cells evenly along the luminal surface can be especially challenging. Perfusion-based cell seeding methods have been shown to promote increased uniformity in initial cell distribution onto porous scaffolds for a variety of tissue engineering applications. We investigate the seeding efficiency of a custom-designed perfusion-based seed-and-culture bioreactor through comparisons to a static injection counterpart method and a more traditional drip seeding method. Murine vascular smooth muscle cells were seeded onto porous tubular electrospun polycaprolactone scaffolds, 2 mm in diameter and 30 mm in length, using the three methods, and allowed to rest for 24 hours. Once harvested, scaffolds were evaluated longitudinally and circumferentially to assess the presence of viable cells using alamarBlue and live/dead cell assays and their distribution with immunohistochemistry and scanning electron microscopy. On average, bioreactor-mediated perfusion seeding achieved 35% more luminal surface coverage when compared to static methods. Viability assessment demonstrated that the total number of viable cells achieved across methods was comparable with slight advantage to the bioreactor-mediated perfusion-seeding method. The method described is a simple, low-cost method to consistently obtain even distribution of seeded cells onto the luminal surfaces of small diameter tubular scaffolds.

Electrospun Carbon Nanotube-Based Scaffolds Exhibit High Conductivity and Cytocompatibility for Tissue Engineering Applications.

Carbon nanotubes (CNTs) are known for their excellent conductive properties. Here, we present two novel methods, “sandwich” (sCNT) and dual deposition (DD CNT), for incorporating CNTs into electrospun polycaprolactone (PCL) and gelatin scaffolds to increase their conductance. Based on CNT percentage, the DD CNT scaffolds contain significantly higher quantities of CNTs than the sCNT scaffolds. The inclusion of CNTs increased the electrical conductance of scaffolds from 0.0 ± 0.00 kS (non-CNT) to 0.54 ± 0.10 kS (sCNT) and 5.22 ± 0.49 kS (DD CNT) when measured parallel to CNT arrays and to 0.25 ± 0.003 kS (sCNT) and 2.85 ± 1.12 (DD CNT) when measured orthogonally to CNT arrays. The inclusion of CNTs increased fiber diameter and pore size, promoting cellular migration into the scaffolds. CNT inclusion also decreased the degradation rate and increased hydrophobicity of scaffolds. Additionally, CNT inclusion increased Young’s modulus and failure load of scaffolds, increasing their mechanical robustness. Murine fibroblasts were maintained on the scaffolds for 30 days, demonstrating high cytocompatibility. The increased conductivity and high cytocompatibility of the CNT-incorporated scaffolds make them appropriate candidates for future use in cardiac and neural tissue engineering.

Study on the Incorporation of Chitosan Flakes in Electrospun Polycaprolactone Scaffolds

Hybrid scaffolds obtained by combining two or more biopolymers are studied in the context of tissue regeneration due to the possibility of achieving new functional properties or structural features. The aim of this work was to produce a new type of hybrid polycaprolactone (PCL)/chitosan (CS) electrospun mat through the controlled deposition of CS flakes interspaced between the PCL fibers. A poly(ethylene oxide) (PEO) solution was used to transport CS flakes with controlled size. This, and the PCL solution, were simultaneously electrospun onto a rotatory mandrel in a perpendicular setup. Different PCL/CS mass ratios were also studied. The morphology of the resulting fibers, evaluated by SEM, confirmed the presence of the CS flakes between the PCL fibers. The addition of PEO/CS fibers resulted in hydrophilic mats with lower Young’s modulus relatively to PCL mats. In vitro cell culture results indicated that the addition of CS lowers both the adhesion and the proliferation of human dermal fibroblasts. The present work demonstrates the feasibility of achieving a controlled deposition of a polymeric component in granular form onto a collector where electrospun nanofibers are being deposited, thereby producing a hybrid scaffold.

Preparation and characterization of electrospun polycaprolactone/brushite scaffolds to promote osteogenic differentiation of mesenchymal stem cells

Bone tissue engineering aims to develop effective strategies for repairing or replacing damaged bone tissue. In this study, composite scaffolds consisting of dicalcium phosphate dihydrate (DCDP, brushite) as a bone phase mineral precursor with different weight percentages (0%, 1%, 3%, 5%, and 10%) in combination with polycaprolactone (PCL) were fabricated by electrospinning technique. The morphology and mechanical behavior of scaffolds were characterized using scanning electron microscopy and tensile strength test, respectively. The bioactivity of scaffolds was assessed in simulated body fluid. Adhesion, viability, proliferation, and differentiation of mesenchymal stem cells derived from the human bone marrow on scaffolds were investigated using electron microscopy, MTT assay, live-dead assay, alizarin red staining, alkaline phosphatase activity and, gene expression analysis by real-time PCR. The results showed that the scaffold containing 3 wt. % of DCDP had the highest tensile strength (15.35 MPa). Furthermore, cells seeded on scaffolds showed over 80% viability after 1, 3, 7 days of incubation. Also, the results showed that the addition of DCDP to the PCL significantly increased the alkaline phosphatase activity. The osteocalcin gene expression in the composite scaffold showed a 6.1-fold increase compared to the pure PCL scaffold. It is concluded that electrospun PCL scaffolds containing DCDP with optimum concentration can be a proper candidate for bone tissue engineering applications.

Attapulgite-doped electrospun PCL scaffolds for enhanced bone regeneration in rat cranium defects

Electrospun PCL scaffolds have been widely used for tissue engineering as they have shown great potential to mimic the structure of the natural extracellular matrix (ECM). However, the small pore size and low bioactivity of the scaffolds limit cell migration and tissue formation. In this study, PCL (polycaprolactone), PCL/PEG (polyethylene glycol), and PCL/PEG/ATP (nano-attapulgite) scaffolds were fabricated via electrospinning. To increase the porosity of the scaffolds, they were washed to remove water-soluble PEG fibers. Then the porous structure was measured using scanning electron microscopy (SEM) and atomic force microscopy (AFM), which showed an increased porosity when PEG fibers were removed in PCL/PEG and PCL/PEG/ATP scaffolds. Moreover, the mechanical properties were also analyzed in dry and wet conditions. In vitro mouse multipotent mesenchymal precursor cells were used to assess the biocompatibility of the scaffolds, and osteogenesis was analyzed using CCK-8 and real-time PCR (RT-PCR) methods. Moreover, in vivo μCT, histological and immunohistochemical analyses were conducted to evaluate new bone formation in rat cranium defect models. Washed PCL/PEG/ATP scaffolds were implanted into the cranium defects in rats for 4 or 8 weeks, better cell infiltration was observed in these scaffolds than in unwashed ones. The result demonstrated that washed PCL/PEG/ATP scaffold facilitated the differentiation of MSCs into osteoblasts compared with PCL scaffold, as proved by the increased expression of osteogenic key genes as well as Smad1, Smad4, and Smad5. Furthermore, in vivo studies demonstrated that using the ATP-doped electrospun PCL scaffold can improve the bone regeneration of rat cranium defects. Particularly, the PCL/ATP-30% scaffold has the best effect compared to the other scaffolds. The enhanced osteogenesis and bone repair were related to the PCL/ATP activated BMP/Smad signaling pathway.

Biologically modified electrospun polycaprolactone nanofibrous scaffold promotes osteogenic differentiation

Tissue engineering has tried for decades to introduce scaffolds to replace the body's natural ECM, to replace damaged tissues that cannot be repaired or treated by conventional methods. In the present study, an attempt has been made to use human placental extract (PE) as a natural material to modify and simulate an electrospun Polycaprolactone (PCL) scaffold to the natural ECM. PCL and PCL-PE nanofibers were characterized morphologically, and their non-toxicity was also investigated. After that, their osteo-supportive capacities were also investigated by culture of the Wharton's jelly (WJ) derived mesenchymal stem cells (MSCs) on the scaffolds. SEM results demonstrated that PCL and PCL-PE scaffolds were fibrous with nanometer size, bead free and smooth, and these characteristics were not changed significantly while PCL nanofibers coated with PE. In addition, SEM results were also confirmed these scaffold's non-toxicity when WJ-MSCs properly attached, proliferated and expanded on the surface of scaffolds. Osteo-supportive capacity of the PCL and PCL-PE scaffolds was investigated via ALP activity, calcium content and bone-related gene expression in the WJ-MSCs when grown on the PCL and PCL-PE scaffolds and TCPS and TCPS-PE as controls. The results demonstrated that all bone related markers were significantly increased at the presence of the PE. In addition, this increase was significantly enhanced when PE combined with PCL nanofiber structure. According to the results, PCL-PE nanofibrous scaffold showed that it has a very high ability to support bone differentiation and can be introduced as a suitable candidate for use in bone tissue engineering.

Examining the Transmission of Visible Light through Electrospun Nanofibrous PCL Scaffolds for Corneal Tissue Engineering.

The transparency of nanofibrous scaffolds is of highest interest for potential applications like corneal wound dressings in corneal tissue engineering. In this study, we provide a detailed analysis of light transmission through electrospun polycaprolactone (PCL) scaffolds. PCL scaffolds were produced via electrospinning, with fiber diameters in the range from (35 ± 13) nm to (167 ± 35) nm. Light transmission measurements were conducted using UV–vis spectroscopy in the range of visible light and analyzed with respect to the influence of scaffold thickness, fiber diameter, and surrounding medium. Contour plots were compiled for a straightforward access to light transmission values for arbitrary scaffold thicknesses. Depending on the fiber diameter, transmission values between 15% and 75% were observed for scaffold thicknesses of 10 µm. With a decreasing fiber diameter, light transmission could be improved, as well as with matching refractive indices of fiber material and medium. For corneal tissue engineering, scaffolds should be designed as thin as possible and fabricated from polymers with a matching refractive index to that of the human cornea. Concerning fiber diameter, smaller fiber diameters should be favored for maximizing graft transparency. Finally, a novel, semi-empirical formulation of light transmission through nanofibrous scaffolds is presented.

The Effect of Anterior Cruciate Ligament Reconstruction with an Electropsun Scaffold on Tibiofemoral Contact Mechanics.

Surgical reconstruction of the torn ACL is performed to restore native contact mechanics. Drawbacks to traditional ACL repair techniques motivate the development of a tissue engineered ACL scaffold. Our group has developed a hierarchical electrospun polycaprolactone (PCL) scaffold that consists of rolled nanofiber bundles attached at each end with solvent-case blocks of PCL. The goal of this study was to compare ovine cadaver tibiofemoral contact mechanics after ACL reconstruction with the electrospun scaffold to a clinically applicable ACL reconstruction with a soft tissue graft and the ACL transected condition (ACLX). In the ACLX group and after ACL reconstruction with either the electrospun scaffold or soft tissue graft, pressure sensors were inserted under the menisci. Loads up to 890 N were applied at various flexion angles. The scaffold performed the best at restoring contact mechanics in the medial hemijoint to that of the native ACL. The scaffold was good at maintaining a medial-lateral balance of pressures as in the native joint whereas the ACLX shifted pressure off the lateral and on to the medial hemijoint. While the ACL scaffold didn't restore mechanics to that of the native condition, it improved contact mechanics compared to the standard graft replacement and ACLX condition.

Functionalization of Electrospun Polycaprolactone Scaffolds with Matrix-Binding Osteocyte-Derived Extracellular Vesicles Promotes Osteoblastic Differentiation and Mineralization

Synthetic polymeric materials have demonstrated great promise for bone tissue engineering based on their compatibility with a wide array of scaffold-manufacturing techniques, but are limited in terms of the bioactivity when compared to naturally occurring materials. To enhance the regenerative properties of these materials, they are commonly functionalised with bioactive factors to guide growth within the developing tissue. Extracellular matrix vesicles (EVs) play an important role in facilitating endochondral ossification during long bone development and have recently emerged as important mediators of cell-cell communication coordinating bone regeneration, and thus represent an ideal target to enhance the regenerative properties of synthetic scaffolds. Therefore, in this paper we developed tools and protocols to enable the attachment of MLO-Y4 osteocyte-derived EVs onto electrospun polycaprolactone (PCL) scaffolds for bone repair. Initially, we optimize a method for the functionalization of PCL materials with collagen type-1 and fibronectin, inspired by the behaviour of matrix vesicles during endochondral ossification, and demonstrate that this is an effective method for the adhesion of EVs to the material surface. We then used this functionalization process to attach osteogenic EVs, collected from mechanically stimulated MLO-Y4 osteocytes, to collagen-coated electrospun PCL scaffolds. The EV-functionalized scaffold promoted osteogenic differentiation (measured by increased ALP activity) and mineralization of the matrix. In particular, EV-functionalised scaffolds exhibited significant increases in matrix mineralization particularly at earlier time points compared to uncoated and collagen-coated controls. This approach to matrix-based adhesion of EVs provides a mechanism for incorporating vesicle signalling into polyester scaffolds and demonstrates the potential of osteocyte derived EVs to enhance the rate of bone tissue regeneration.

Fatty acid synthase as a feasible biomarker for triple negative breast cancer stem cell subpopulation cultured on electrospun scaffolds.

There is no targeted therapy for triple negative breast cancer (TNBC), which presents an aggressive profile and poor prognosis. Recent studies noticed the feasibility of breast cancer stem cells (BCSCs), a small population responsible for tumor initiation and relapse, to become a novel target for TNBC treatments. However, new cell culture supports need to be standardized since traditional two-dimensional (2D) surfaces do not maintain the stemness state of cells. Hence, three-dimensional (3D) scaffolds represent an alternative to study in vitro cell behavior without inducing cell differentiation. In this work, electrospun polycaprolactone scaffolds were used to enrich BCSC subpopulation of MDA-MB-231 and MDA-MB-468 TNBC cells, confirmed by the upregulation of several stemness markers and the existence of an epithelial-to-mesenchymal transition within 3D culture. Moreover, 3D-cultured cells displayed a shift from MAPK to PI3K/AKT/mTOR signaling pathways, accompanied by an enhanced EGFR and HER2 activation, especially at early cell culture times. Lastly, the fatty acid synthase (FASN), a lipogenic enzyme overexpressed in several carcinomas, was found to be hyperactivated in stemness-enriched samples. Its pharmacological inhibition led to stemness diminishment, overcoming the BCSC expansion achieved in 3D culture. Therefore, FASN may represent a novel target for BCSC niche in TNBC samples.

Electrospun Antimicrobial, Anti‐Inflammatory, and Analgesic Bandages for Comprehensive Wound Treatment

Chronic wounds affect more than 5 million Americans annually with an associated cost of $10 – 20 billion. These wounds provide perfect environments for bacterial growth, and are prone to infections, especially from multi-drug resistant (MDR) pathogens. The current silver-based bandages used to treat wounds exhibit a high toxicity toward fibroblasts, and lack anti-inflammatory and analgesic activity. Our work focuses on the development of bandages to address these unmet clinical needs. We have fabricated electrospun polycaprolactone (PCL) scaffolds, capable of aiding in the wound healing process, and with incorporation of Ag+IBU, a novel therapeutic. These scaffolds deliver the drug locally at a controlled rate to impede bacterial infections. We have further functionalized PCL scaffolds with addition of polyethylene glycol (PEG) to accelerate drug release. Scanning electron microscopy images have revealed that our drug loaded scaffolds have a smooth fiber morphology and fiber diameter that is ~1 mm. Loading and release experiments were conducted by generating a standard curve for Ag+IBU using a Cytation 5 plate reader. Scaffolds loaded with either 5% or 10% Ag+IBU (w/w) release 40% of the drug within the first 24 hours. We have determined the antimicrobial efficacy of drug loaded scaffolds against planktonic and biofilm growth mode bacteria by measuring bacterial inhibition after incubation with scaffold for 24 hours. Microbiological assays have revealed that Ag+IBU-loaded scaffolds are bactericidal against bacteria in both planktonic and biofilm growth mode. Cellular toxicity was determined against Human Dermal Fibroblasts using alamarBlue assay. Cytotoxicity assays have revealed that Ag+IBU-loaded scaffolds exhibit toxicity toward human dermal fibroblasts at high concentrations. However, pre-incubation with N-acetyl cysteine (NAC), an antioxidant metabolite, abrogates this toxicity and significantly increases cell viability. We have fabricated two-layer scaffolds with one layer rapidly delivering NAC and the second layer slowly releasing Ag+IBU. Compared with the commercially available bandages with antimicrobial properties currently used for wounds, our non-toxic, antimicrobial, anti-inflammatory, and analgesic scaffolds offer a more comprehensive treatment option.

Effects of Scaffold Pore Morphologies on Glucose Transport Limitations in Hollow Fibre Membrane Bioreactor for Bone Tissue Engineering: Experiments and Numerical Modelling.

In the current research, three electrospun polycaprolactone (PCL) scaffolds with different pore morphology induced by changing the electrospinning parameters, spinning time and rate, have been prepared in order to provide a fundamental understanding on the effects pore morphology have on nutrient transport behaviour in hollow fibre membrane bioreactor (HFMB). After determining the porosity of the scaffolds, they were investigated for glucose diffusivity using cell culture media (CCM) and distilled water in a diffusion cell at 37 °C. The scanning electron microscope (SEM) images of the microstructure of the scaffolds were analysed further using ImageJ software to determine the porosity and glucose diffusivity. A Krogh cylinder model was used to determine the glucose transport profile with dimensionless variables within the HFMB. The paper discusses the roles of various dimensionless numbers (e.g., Péclet and Damköhler numbers) and non-dimensional groups of variables (e.g., non-dimensional fibre radius) on determining glucose concentration profiles, especially in the scaffold region. A negative linear relationship between glucose diffusivities across PCL scaffolds and the minimum glucose concentrations (i.e., concentration on the outer fibre edge on the outlet side (at z = 1 and r = 3.2) was also found. It was shown that the efficiency of glucose consumption improves with scaffolds of higher diffusivities. The results of this study are expected to help in optimizing designs of HFMB as well as carry out more accurate up scaling analyses for the bioreactor.

Role of PEGylated CdSe-ZnS quantum dots on structural and functional properties of electrospun polycaprolactone scaffolds for blood vessel tissue engineering

Conjugation of quantum dots (Q-dots) into tissue engineering scaffolds is extremely beneficial for designing composite scaffolds imparting multifunctional properties. In the present work, we report the efficacy of incorporating the PEGylated CdSe-ZnS (Q-dots) into electrospun poly(caprolactone)(PCL) scaffolds whose properties were evaluated for small diameter blood vessel applications. Incorporation of Q-dots was found to result in significant reduction in fiber diameter of electrospun scaffolds. Corresponding pore size ranges varied from 12 to 36 µm for composite scaffold compared with 12–60 µm in bare scaffold. Both PCL and composite scaffolds were found to possess better mechanical strength and elasticity than that of native arteries. Contact angle measurements revealed hydrophobic nature of scaffolds which significantly improved upon modification with fibrin. PCL/Q-dot composite scaffolds were found to possess optimum micro-structure for supporting uniform endothelial cell growth after 5 days of culture compared to the pristine PCL scaffold.

The effect of adding reduced graphene oxide to electrospun polycaprolactone scaffolds on MG-63 cells activity

While providing a proper matrix for cellular responses, bone tissue engineering scaffolds can deal with the shortcomings of conventional treatment methods and enhance bone regeneration. In the current study, graphene oxide (GO) nanoparticles were reduced using L-ascorbic acid, a green reductant. Electrospun polycaprolactone (PCL) and polycaprolactone-reduced graphene oxide (PCL/rGO) scaffolds were fabricated. Fourier transform infrared spectroscopy confirmed the correct synthesis of reduced graphene oxide (rGO). The addition of rGO to electrospun PCL has increased the fiber diameter and surface roughness. Mechanical properties evaluation in a dry environment indicated that elastic modulus and ultimate tensile strength declined in PCL/rGO scaffolds while strain at break improved; however, all mechanical values decreased in wet conditions. Studies on bioactivity suggest that apatite deposition requires time to occur on PCL/rGO scaffolds in vitro. This phenomenon was confirmed by Ca/P ratios obtained from EDX quantitive data. Furthermore, the degradation rate of electrospun PCL accelerated in the scaffolds enriched with rGO. Biological evaluations such as cell viability, cell attachment, and alkaline phosphatase activity were carried out using MG-63 cell lines. A significant difference has been observed in cell viability and alkaline phosphatase activity in the PCL scaffold containing 1 wt% rGO compared to pure PCL (P < 0.05). Overall, results indicated the critical correlation between rGO dosage in electrospun PCL scaffolds and MG-63 cell behavior for bone tissue applications.

Sputter-Deposited Ag Nanoparticles on Electrospun PCL Scaffolds: Morphology, Wettability and Antibacterial Activity

Porous scaffolds made of biocompatible and environmental-friendly polymer fibers with diameters in the nano/micro range can find applications in a wide variety of sectors, spanning from the biomedical field to textiles and so on. Their development has received a boost in the last decades thanks to advances in the production methods, such as the electrospinning technique. Conferring antimicrobial properties to these fibrous structures is a primary requirement for many of their applications, but the addition of antimicrobial agents by wet methods can present a series of drawbacks. In this work, strong antibacterial action is successfully provided to electrospun polycaprolactone (PCL) scaffolds by silver (Ag) addition through a simple and flexible way, namely the sputtering deposition of silver onto the PCL fibers. SEM-EDS analyses demonstrate that the polymer fibers get coated by Ag nanoparticles without undergoing any alteration of their morphological integrity upon the deposition process. The influence on wettability is evaluated with polar (water) and non-polar (diiodomethane) liquids, evidencing that this coating method allows preserving the hydrophobic character of the PCL polymer. Excellent antibacterial action (reduction &gt; 99.995% in 4 h) is demonstrated against Escherichia coli. The easy fabrication of these PCL-Ag mats can be applicable to the production of biomedical devices, bioremediation and antifouling systems in filtration, personal protective equipment (PPE), food packaging materials, etc.

Morphological and Mechanical Properties of Electrospun Polycaprolactone Scaffolds: Effect of Applied Voltage.

The aim of this work is to investigate the effect of the applied voltage on the morphological and mechanical properties of electrospun polycaprolactone (PCL) scaffolds for potential use in tissue engineering. The morphology of the scaffolds was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and the BET techniques for measuring the surface area and pore volume. Stress-strain curves from tensile tests were obtained for estimating the mechanical properties. Additional studies for detecting changes in the chemical structure of the electrospun PCL scaffolds by Fourier transform infrared were performed, while contact angle and X-ray diffraction analysis were realized for determining the wettability and crystallinity, respectively. The SEM, AFM and BET results demonstrate that the electrospun PCL fibers exhibit morphological changes with the applied voltage. By increasing the applied voltage (10 to 25 kV) a significate influence was observed on the fiber diameter, surface roughness, and pore volume. In addition, tensile strength, elongation, and elastic modulus increase with the applied voltage, the crystalline structure of the fibers remains constant, and the surface area and wetting of the scaffolds diminish. The morphological and mechanical properties show a clear correlation with the applied voltage and can be of great relevance for tissue engineering.

Synergy effect of Urtica dioica and ZnO NPs on microstructure, antibacterial activity and cytotoxicity of electrospun PCL scaffold for wound dressing application

This study focuses on the synergy effect of Urtica dioica as a natural medicinal plant and ZnO nanoparticles (NPs) as a common and active antibacterial metal oxide on the microstructure, composition, mechanical properties, hydrophobicity, antibacterial activity, and fibroblast cell cytotoxicity of biocompatible polycaprolactone (PCL) scaffolds. The nanostructured fibrous pristine and hybrid scaffolds were provided using the electrospinning method. The microstructure of scaffolds was characterized using FESEM, EDS, FTIR. The results indicated that the incorporation of Urtica dioica and ZnO NPs have a significant impact on the morphology and molecular bond groups of the PCL scaffold. The evaluation of the strain-stress curve of scaffolds depicted that the incorporation of Urtica dioica enhances the tensile strength from 1.52 MPa to 2.54 MPa. The incorporation of Urtica dioica and ZnO NPs improves the water uptake ability, regulates the water affinity between hydrophobicity-hydrophilicity and controls the release of Urtica dioica. The hybrid composition made the highest antibacterial hybrid scaffold against E. coli and S. aureus. Cell cytotoxicity studies using fibroblast L929 cells also showed that the highest cell viability (97.8 %) is for a hybrid Urtica dioica and ZnO scaffold where the proper cell adhesion to fibers of the scaffold with a polar shape morphology occurs. Our findings suggest that incorporation of 4 wt.% of Urtica dioica and 1 wt.% of ZnO NPs to PCL scaffold leads to the best properties for wound dressing application.

Modeling tensile strength and suture retention of polycaprolactone electrospun nanofibrous scaffolds by artificial neural networks

Electrospun polycaprolactone (PCL) scaffolds are broadly used in tissue engineering applications due to their superior biomechanical properties and compatibility with the cell matrix. The properties of PCL scaffolds depend on electrospinning parameters. The relationships between electrospinning process parameters and scaffold properties are complicated and nonlinear. In this study, we used the artificial neural networks (ANN) technique to estimate the tensile strength and suture retention of PCL scaffolds as a function of electrospinning parameters (polymer concentration, solution feed rate, applied voltage, and nozzle to collector distance). A standalone ANN software was developed, and the predicted properties were a good agreement with the experimental data. The present model has excellent learning precision for both training and testing data sets. The precise predictions revealed that the model could estimate the relationships between electrospinning parameters and properties of PCL scaffolds adequately.