A comparison of nanoscale and multiscale PCL/gelatin scaffolds prepared by disc-electrospinning

Electrospinning technologies for the delivery of Biopharmaceuticals: Current status and future trends

This review provides an in-depth exploration of electrospinning techniques employed to produce micro- or nanofibres of biopharmaceuticals using polymeric solutions or melts with high-voltage electricity. Distinct from prior reviews, the current work narrows its focus on the recent developments and advanced applications in biopharmaceutical formulations. It begins with an overview of electrospinning principles, covering both solution and melt modes. Various methods for incorporating biopharmaceuticals into electrospun fibres, such as surface adsorption, blending, emulsion, co-axial, and high-throughput electrospinning, are elaborated. The review also surveys a wide array of biopharmaceuticals formulated through electrospinning, thereby identifying both opportunities and challenges in this emerging field. Moreover, it outlines the analytical techniques for characterizing electrospun fibres and discusses the legal and regulatory requirements for their production. This work aims to offer valuable insights into the evolving realm of electrospun biopharmaceutical delivery systems.

In Vitro Investigation of Gelatin/Polycaprolactone Nanofibers in Modulating Human Gingival Mesenchymal Stromal Cells

The aesthetic constancy and functional stability of periodontium largely depend on the presence of healthy mucogingival tissue. Soft tissue management is crucial to the success of periodontal surgery. Recently, synthetic substitute materials have been proposed to be used for soft tissue augmentation, but the tissue compatibility of these materials needs to be further investigated. This study aims to assess the in vitro responses of human gingival mesenchymal stromal cells (hG-MSCs) cultured on a Gelatin/Polycaprolactone prototype (GPP) and volume-stable collagen matrix (VSCM). hG-MSCs were cultured onto the GPP, VSCM, or plastic for 3, 7, and 14 days. The proliferation and/or viability were measured by cell counting kit-8 assay and resazurin-based toxicity assay. Cell morphology and adhesion were evaluated by microscopy. The gene expression of collagen type I, alpha1 (COL1A1), α-smooth muscle actin (α-SMA), fibroblast growth factor (FGF-2), vascular endothelial growth factor A (VEGF-A), transforming growth factor beta-1 (TGF-β1), focal adhesion kinase (FAK), integrin beta-1 (ITG-β1), and interleukin 8 (IL-8) was investigated by RT-qPCR. The levels of VEGF-A, TGF-β1, and IL-8 proteins in conditioned media were tested by ELISA. GPP improved both cell proliferation and viability compared to VSCM. The cells grown on GPP exhibited a distinct morphology and attachment performance. COL1A1, α-SMA, VEGF-A, FGF-2, and FAK were positively modulated in hG-MSCs on GPP at different investigation times. GPP increased the gene expression of TGF-β1 but had no effect on protein production. The level of ITG-β1 had no significant changes in cells seeded on GPP at 7 days. At 3 days, notable differences in VEGF-A, TGF-β1, and α-SMA expression levels were observed between cells seeded on GPP and those on VSCM. Meanwhile, GPP showed higher COL1A1 expression compared to VSCM after 14 days, whereas VSCM demonstrated a more significant upregulation in the production of IL-8. Taken together, our data suggest that GPP electrospun nanofibers have great potential as substitutes for soft tissue regeneration in successful periodontal surgery.

PCL/Agarose 3D-printed scaffold for tissue engineering applications: fabrication, characterization, and cellular activities

Background and purpose

Biomaterials, scaffold manufacturing, and design strategies with acceptable mechanical properties are the most critical challenges facing tissue engineering.

Experimental approach

In this study, polycaprolactone (PCL) scaffolds were fabricated through a novel three-dimensional (3D) printing method. The PCL scaffolds were then coated with 2% agarose (Ag) hydrogel. The 3D-printed PCL and PCL/Ag scaffolds were characterized for their mechanical properties, porosity, hydrophilicity, and water absorption. The construction and morphology of the printed scaffolds were evaluated via Fourier-Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The attachment and proliferation of L929 cells cultured on the scaffolds were investigated through MTT assay on the cell culture study upon the 1st, 3rd, and 7th days.

Findings/Results

The incorporation of Ag hydrogel with PCL insignificantly decreased the mechanical strength of the scaffold. The presence of Ag enhanced the hydrophilicity and water absorption of the scaffolds, which could positively influence their cell behavior compared to the PCL scaffolds. Regarding cell morphology, the cells on the PCL scaffolds had a more rounded shape and less cell spreading, representing poor cell attachment and cell-scaffold interaction due to the hydrophobic nature of PCL. Conversely, the cells on the PCL/Ag scaffolds were elongated with a spindle-shaped morphology indicating a positive cell-scaffold interaction.

Conclusion and implications

PCL/Ag scaffolds can be considered appropriate for tissue-engineering applications.

Bioactive Nanostructured Scaffold-Based Approach for Tendon and Ligament Tissue Engineering

An effective therapeutic strategy to treat tendon or ligament injury continues to be a clinical challenge due to the limited natural healing capacity of these tissues. Furthermore, the repaired tendons or ligaments usually possess inferior mechanical properties and impaired functions. Tissue engineering can restore the physiological functions of tissues using biomaterials, cells, and suitable biochemical signals. It has produced encouraging clinical outcomes, forming tendon or ligament-like tissues with similar compositional, structural, and functional attributes to the native tissues. This paper starts by reviewing tendon/ligament structure and healing mechanisms, followed by describing the bioactive nanostructured scaffolds used in tendon and ligament tissue engineering, with emphasis on electrospun fibrous scaffolds. The natural and synthetic polymers for scaffold preparation, as well as the biological and physical cues offered by incorporating growth factors in the scaffolds or by dynamic cyclic stretching of the scaffolds, are also covered. It is expected to present a comprehensive clinical, biological, and biomaterial insight into advanced tissue engineering-based therapeutics for tendon and ligament repair.

Enhancement of AFB1 Removal Efficiency via Adsorption/Photocatalysis Synergy Using Surface-Modified Electrospun PCL-g-C3N4/CQDs Membranes

Aflatoxin B₁ (AFB₁) is a highly toxic mycotoxin produced by aspergillus species under specific conditions as secondary metabolites. In this study, types of PCL (Polycaprolactone) membranes anchored (or not) to g-C₃N₄/CQDs composites were prepared using electrospinning technology with (or without) the following surface modification treatment to remove AFB₁. These membranes and g-C₃N₄/CQDs composites were characterized by SEM, TEM, UV-vis, XRD, XPS and FTIR to analyze their physical and chemical properties. Among them, the modified PCL-g-C₃N₄/CQDs electrospun membranes exhibited an excellent ability to degrade AFB₁ via synergistic effects of adsorption and photocatalysis, and the degradation rate of 0.5 μg/mL AFB₁ solution was observed to be up to 96.88% in 30 min under visible light irradiation. Moreover, the modified PCL-g-C₃N₄/CQDs electrospun membranes could be removed directly after the reaction process without centrifugal or magnetic separation, and the regeneration was a green approach synchronized with the reaction under visible light avoiding physical or chemical treatment. The mechanism of adsorption by electrostatic attraction and hydrogen bonding interaction was revealed and the mechanism of photodegradation of AFB₁ was also proposed based on active species trapping experiments. This study illuminated the highly synergic adsorption and photocatalytic AFB₁ removal efficiency without side effects from the modified PCL-g-C₃N₄/CQDs electrospun membranes, thereby offering a continual and green solution to AFB₁ removal in practical application.

Development of high resilience spiral wound suture-embedded gelatin/PCL/heparin nanofiber membrane scaffolds for tendon tissue engineering

This study develops a spiral wound scaffold based on gelatin/PCL/heparin (GPH) nanofiber membranes for tendon tissue engineering. By embedding sutures in dual layers of aligned GPH nanofiber membranes, prepared from mixed electrospinning of gelatin and PCL/heparin solutions, we fabricate a high resilience scaffold intended for the high loading environment experienced by tendons. The basic fibroblast growth factor (bFGF) was anchored to GPH scaffold through bioaffinity between heparin and bFGF, aim to provide biological cues for maintenance of tenogenic phenotype. In addition, the aligned nanofiber morphology is expected to provide physical cues toward seeded tenocytes. With sustained release of bFGF, GPH-bFGF can enhance proliferation, up-regulate tenogenic gene expression, and increase synthesis of tendon-specific proteins by tenocytes in vitro. Furthermore, by properly maintaining tendon phenotypes, GPH-bFGF/tenocytes constructs showed improved mechanical properties over GPH-bFGF. From in vivo study using GPH-bFGF/tenocytes constructs to repair rabbit Achilles tendon defects, neotendon tissue formation was confirmed from histological staining and biomechanical analysis. These findings collectively demonstrate that the newly designed GPH-bFGF scaffold could provide a niche for inducing tendon tissue regeneration by effectively restoring the tendon tissue structure and function.

Applications of electrospun scaffolds with enlarged pores in tissue engineering

Despite electrospinning has multiple advantages over other methods such as creating materials with superfine fiber diameter, high specific surface area, and good mechanical properties, the pore diameter of scaffolds prepared...

Hemolytic, Biocompatible, and Functional Effect of Cellularized Polycaprolactone-Hydrolyzed Collagen Electrospun Membranes for Possible Application as Vascular Implants

In search of bioactive vascular prostheses that exhibit greater biocompatibility through the combination of natural and synthetic polymers, tissue engineering from a biomimetic perspective has proposed the development of three-dimensional structures as therapeutic strategies in the field of cardiovascular medicine. Techniques such as electrospinning allow obtaining of scaffolds that emulate the microarchitecture of the extracellular matrix of native vessels; thus, this study aimed to evaluate the biological influence of microarchitecture on polycaprolactone (PCL) and hydrolyzed collagen (H-Col) electrospun scaffolds, which have a homogeneous (microscale) or heterogeneous (micro-nanoscale) fibrillar structure. The hemolytic, biocompatible, and functional effect of the scaffolds in interaction with an in vitro fibroblast model was determined, in view of its potential use for vascular implants. Scaffolds were characterized by scanning electron microscopy and atomic force microscopy, Fourier transform infrared spectroscopy, wettability, static permeability, tensile test, and degradation. In addition, direct and indirect 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were used to identify the cell viability of fibroblasts, fluorescence assays were performed to establish morphological changes of the cell nuclei, and the hemolytic effect of the scaffolds was calculated. Results showed that ethanol-treated biocompositescaffolds exhibited mass losses lower than 6.65% and slow wettability and absorption, resulting from an increase in secondary structures that contribute to the crystalline phase of H-Col. The scaffolds demonstrated stable degradation in saline during the incubation period because of the availability of soluble structures in aqueous media, and the inclusion of H-Col increased the elastic properties of the scaffold. As regards hemocompatibility, the scaffolds had hemolysis levels lower than 1%; moreover, in terms of biocompatible characteristics, scaffolds exhibited good adhesion, proliferation, and cell viability and insignificant changes in the circularity of the cell nuclei. However, scaffolds with homogeneous fibers showed cell agglomerates after 48 h of interaction. By contrast, permeability decreased as the incubation period progressed, because of the cellularization of the three-dimensional structure. In conclusion, multiscale scaffolds could exhibit a suitable behavior as a bioactive small-diameter vascular implant.

Electrohydrodynamic 3D Printing Scaffolds for Repair of Achilles Tendon Defect in Rats

Tissue engineering (TE) studies for Achilles tendon (AT) defects are a difficult and popular field in orthopedic medical practice. In this study, we applied electrohydrodynamic three-dimensional (3D) printing technology to construct scaffolds made of poly-(ɛ-ɛ-caprolactone) (PCL) and Pluronic F127 (F127) with different mass-volume ratios. The fibers and porous capabilities of the scaffolds were controlled using this technology. We found that F127 improved the hydrophilicity and degradation of PCL in vitro. The PCL scaffolds with 5% F127 were mostly favorable for cell adhesion and growth, suggesting that the scaffolds had good biocompatibility in vitro. Scaffolds with 5% F127 seeded with C3H10T1/2 cells were transplanted into AT defects in rats. A histological analysis indicated that the TE scaffolds were beneficial for the accumulation and arrangement of collagen fibers. Thus, this study provides fundamental experimental data for future clinical applications regarding TE for ATs.

Electrospun Polyvinylpyrrolidone-Gelatin and Cellulose Acetate Bi-Layer Scaffold Loaded with Gentamicin as Possible Wound Dressing

Acceleration of wound healing can be achieved with the use of wound dressings. Through the electrospinning technique, a polymeric scaffold composed of two layers was processed: a gelatin and polyvinylpyrrolidone layer with gentamicin, and a second layer of cellulose acetate. The conditions for the electrospinning process were standardized for voltage parameters, feed flow and the distance from the injector to the collector. Once the values of the main variables for the electrospinning were optimized, a three-hour processing time was established to allow the separation of the material from the collector. The obtained material was characterized by observations on scanning electron microscopy, Fourier transform infrared spectroscopy and thermal analysis; contact angle measurement was performed to evaluate wettability properties, and antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus were evaluated using the Kirby–Bauer test. The obtained fibers that form the bi-layer scaffold present diameters from 100 to 300 nm. The scaffold presents chemical composition, thermal stability, wettability characteristics and antibacterial activity that fulfill the proposal from this study, based on obtaining a scaffold that could be used as a drug delivery vehicle and a wound dressing material.

Polycaprolactone/Gelatin/Hyaluronic Acid Electrospun Scaffolds to Mimic Glioblastoma Extracellular Matrix

Glioblastoma (GBM), one of the most malignant types of human brain tumor, is resistant to conventional treatments and is associated with poor survival. Since the 3D extracellular matrix (ECM) of GBM microenvironment plays a significant role on the tumor behavior, the engineering of the ECM will help us to get more information on the tumor behavior and to define novel therapeutic strategies. In this study, polycaprolactone (PCL)/gelatin(Gel)/hyaluronic acid(HA) composite scaffolds with aligned and randomly oriented nanofibers were successfully fabricated by electrospinning for mimicking the extracellular matrix of GBM tumor. We investigated the effect of nanotopography and components of fibers on the mechanical, morphological, and hydrophilic properties of electrospun nanofiber as well as their biocompatibility properties. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) have been used to investigate possible interactions between components. The mean fiber diameter in the nanofiber matrix was increased with the presence of HA at low collector rotation speed. Moreover, the rotational velocity of the collector affected the fiber diameters as well as their homogenous distribution. Water contact angle measurements confirmed that hyaluronic acid-incorporated aligned nanofibers were more hydrophilic than that of random nanofibers. In addition, PCL/Gel/HA nanofibrous scaffold (7.9 MPa) exhibited a significant decrease in tensile strength compared to PCL/Gel nanofibrous mat (19.2 MPa). In-vitro biocompatibilities of nanofiber scaffolds were tested with glioblastoma cells (U251), and the PCL/Gel/HA scaffolds with random nanofiber showed improved cell adhesion and proliferation. On the other hand, PCL/Gel/HA scaffolds with aligned nanofiber were found suitable for enhancing axon growth and elongation supporting intracellular communication. Based on these results, PCL/Gel/HA composite scaffolds are excellent candidates as a biomimetic matrix for GBM and the study of the tumor.

A Mini-Review: Needleless Electrospinning of Nanofibers for Pharmaceutical and Biomedical Applications

Electrospinning (ES) is a convenient and versatile method for the fabrication of nanofibers and has been utilized in many fields including pharmaceutical and biomedical applications. Conventional ES uses a needle spinneret for the generation of nanofibers and is associated with many limitations and drawbacks (i.e., needle clogging, limited production capacity, and low yield). Needleless electrospinning (NLES) has been proposed to overcome these problems. Within the last two decades (2004–2020), many research articles have been published reporting the use of NLES for the fabrication of polymeric nanofibers intended for drug delivery and biomedical tissue engineering applications. The objective of the present mini-review article is to elucidate the potential of NLES for designing such novel nanofibrous drug delivery systems and tissue engineering constructs. This paper also gives an overview of the key NLES approaches, including the most recently introduced NLES method: ultrasound-enhanced electrospinning (USES). The technologies underlying NLES systems and an evaluation of electrospun nanofibers are presented. Even though NLES is a promising approach for the industrial production of nanofibers, it is a multivariate process, and more research work is needed to elucidate its full potential and limitations.

Chitosan/poly(ε-caprolactone)-block-poly(ethylene glycol) copolymer electrospun membrane for the adsorption of dyes

The CS/PCL-(b-PEG) nanofibers with controllable core to shell ratio were fabricated as an adsorbent for dye adsorption.

Selection of the optimum 3D-printed pore and the surface modification techniques for tissue engineering tracheal scaffold in vivo reconstruction

The influences of pore sizes and surface modifications on biomechanical properties and biocompatibility (BC) of porous tracheal scaffolds (PTSs) fabricated by polycaprolactone (PCL) using 3D printing technology. The porous grafts were surface-modified through hydrolysis, amination, and nanocrystallization treatment. The surface properties of the modified grafts were characterized by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The materials were cocultured with bone marrow mesenchymal stem cells (BMSCs). The effect of different pore sizes and surface modifications on the cell proliferation behavior was evaluated by the cell counting kit-8 (CCK-8). Compared to native tracheas, the PTS has good biomechanical properties. A pore diameter of 200 μm is the optimum for cell adhesion, and the surface modifications successfully improved the cytotropism of the PTS. Allogeneic implantation confirmed that it largely retains its structural integrity in the host, and the immune rejection reaction of the PTS decreased significantly after the acute phase. Nano-silicon dioxide (NSD)-modified PTS is a promising material for tissue engineering tracheal reconstruction. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 360-370, 2019.

Antibacterial and Barrier Properties of Gelatin Coated by Electrospun Polycaprolactone Ultrathin Fibers Containing Black Pepper Oleoresin of Interest in Active Food Biopackaging Applications

The present study evaluated the effect of using electrospun polycaprolactone (PCL) as a barrier coating and black pepper oleoresin (OR) as a natural extract on the morphology, thermal, mechanical, antimicrobial, oxygen, and water vapor barrier properties of solvent cast gelatin (GEL). The antimicrobial activity of the developed multilayer system obtained by the so-called electrospinning coating technique was also evaluated against Staphylococcus aureus strains for 10 days. The results showed that the multilayer system containing PCL and OR increased the thermal resistance, elongated the GEL film, and significantly diminished its permeance to water vapor. Active multilayer systems stored in hermetically closed bottles increased their antimicrobial activity after 10 days by inhibiting the growth of Staphylococcus aureus. This study demonstrates that addition of electrospun PCL ultrathin fibers and OR improved the properties of GEL films, which promoted its potential use in active food packaging applications.

Fabrication of Magnetic Nanofibers by Needleless Electrospinning from a Self-Assembling Polymer Ferrofluid Cone Array

Magnetic nanofiber has been widely applied in biomedical fields due to its distinctive size, morphology, and properties. We proposed a novel needleless electrospinning method to prepare magnetic nanofibers from the self-assembling "Taylor cones" of poly(vinyl pyrrolidone) (PVP)/Fe₃O₄ ferrofluid (PFF) under the coincident magnetic and electric fields. The results demonstrated that a static PFF Rosensweig instability with a conical protrusion could be obtained under the magnetic field. The tip of the protrusion emitted an electrospinning jet under the coincident magnetic and electric fields. The needleless electrospinning showed a similar process phenomenon in comparison with conventional electrospinning. The prepared nanofibers were composed of Fe₃O₄ particles and PVP polymer. The Fe₃O₄ particles aggregated inside and on the surface of the nanofibers. The nanofibers prepared by needleless electrospinning exhibited similar morphology compared with the conventionally electrospun nanofibers. The nanofibers also exhibited good ferromagnetic and magnetic field responsive properties.

A comparison study between electrospun polycaprolactone and piezoelectric poly(3-hydroxybutyrate-co-3-hydroxyvalerate) scaffolds for bone tissue engineering

In this study, bone scaffolds composed of polycaprolactone (PCL), piezoelectric poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and a combination of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and silicate containing hydroxyapatite (PHBV-SiHA) were successfully fabricated by a conventional electrospinning process. The morphological, chemical, wetting and biological properties of the scaffolds were examined. All fabricated scaffolds are composed of randomly oriented fibres with diameters from 800nm to 12μm. Fibre size increased with the addition of SiHA to PHBV scaffolds. Moreover, fibre surface roughness in the case of hybrid scaffolds was also increased. XRD, FTIR and Raman spectroscopy were used to analyse the chemical composition of the scaffolds, and contact angle measurements were performed to reveal the wetting behaviour of the synthesized materials. To determine the influence of the piezoelectric nature of PHBV in combination with SiHA nanoparticles on cell attachment and proliferation, PCL (non-piezoelectric), pure PHBV, and PHBV-SiHA scaffolds were seeded with human mesenchymal stem cells (hMSCs). In vitro study on hMSC adhesion, viability, spreading and osteogenic differentiation showed that the PHBV-SiHA scaffolds had the largest adhesion and differentiation abilities compared with other scaffolds. Moreover, the piezoelectric PHBV scaffolds have demonstrated better calcium deposition potential compared with non-piezoelectric PCL. The results of the study revealed pronounced advantages of hybrid PHBV-SiHA scaffolds to be used in bone tissue engineering.

Plasma modified PLA electrospun membranes for actinorhodin production intensification in Streptomyces coelicolor immobilized-cell cultivations

Most of industrially relevant bioproducts are produced by submerged cultivations of actinomycetes. The immobilization of these Gram-positive filamentous bacteria on suitable porous supports may prevent mycelial cell-cell aggregation and pellet formation which usually negatively affect actinomycete submerged cultivations, thus, resulting in an improved biosynthetic capability. In this work, electrospun polylactic acid (PLA) membranes, subjected or not to O₂-plasma treatment (PLA-plasma), were used as support for immobilized-cell submerged cultivations of Streptomyces coelicolor M145. This strain produces different bioactive compounds, including the blue-pigmented actinorhodin (ACT) and red-pigmented undecylprodigiosin (RED), and constitutes a model for the study of antibiotic-producing actinomycetes. Wet contact angles and X-ray photoelectron spectroscopy analysis confirmed the increased wettability of PLA-plasma due to the formation of polar functional groups such as carboxyl and hydroxyl moieties. Scanning electron microscope observations, carried out at different incubation times, revealed that S. coelicolor immobilized-cells created a dense "biofilm-like" mycelial network on both kinds of PLA membranes. Cultures of S. coelicolor immobilized-cells on PLA or PLA-plasma membranes produced higher biomass (between 1.5 and 2 fold) as well as higher levels of RED and ACT than planktonic cultures. In particular, cultures of immobilized-cells on PLA and PLA-plasma produced comparable levels of RED that were approximatively 4 and 5 fold higher than those produced by planktonic cultures, respectively. In contrast, levels of ACT produced by immobilized-cell cultures on PLA and PLA-plasma were different, being 5 and 10 fold higher than those of planktonic cultures, respectively. Therefore, this is study demonstrated the positive influence of PLA membrane on growth and secondary metabolite production in S. coelicolor and also revealed that O₂-plasma treated PLA membranes specifically promoted higher ACT production than not treated membranes.

Nanocarbons in Electrospun Polymeric Nanomats for Tissue Engineering: A Review

Electrospinning is a versatile process technology, exploited for the production of fibers with varying diameters, ranging from nano- to micro-scale, particularly useful for a wide range of applications. Among these, tissue engineering is particularly relevant to this technology since electrospun fibers offer topological structure features similar to the native extracellular matrix, thus providing an excellent environment for the growth of cells and tissues. Recently, nanocarbons have been emerging as promising fillers for biopolymeric nanofibrous scaffolds. In fact, they offer interesting physicochemical properties due to their small size, large surface area, high electrical conductivity and ability to interface/interact with the cells/tissues. Nevertheless, their biocompatibility is currently under debate and strictly correlated to their surface characteristics, in terms of chemical composition, hydrophilicity and roughness. Among the several nanofibrous scaffolds prepared by electrospinning, biopolymer/nanocarbons systems exhibit huge potential applications, since they combine the features of the matrix with those determined by the nanocarbons, such as conductivity and improved bioactivity. Furthermore, combining nanocarbons and electrospinning allows designing structures with engineered patterns at both nano- and microscale level. This article presents a comprehensive review of various types of electrospun polymer-nanocarbon currently used for tissue engineering applications. Furthermore, the differences among graphene, carbon nanotubes, nanodiamonds and fullerenes and their effect on the ultimate properties of the polymer-based nanofibrous scaffolds is elucidated and critically reviewed.

Melt electrospinning vs. solution electrospinning: A comparative study of drug-loaded poly (ε-caprolactone) fibres

Curcumin-loaded poly (ε-caprolactone) (PCL) fibres prepared by melt and solution electrospinning methods were both fabricated to investigate their difference in characterization and drug release behaviour. The increasing curcumin content did not influence the morphologies of melt electrospun fibre, but enhanced the range of diameter distribution of solution electrospun fibre owing to the curcumin aggregates in the spinning solution which disturbed the stability of jet. Moreover, a large amount of curcumin with amorphous state could be loaded in the melt electrospun fibre. Whereas the limited solubility of curcumin in the solvent led to the drug aggregates dispersing within the solution electrospun fibre. In addition, the melt electrospun fibres had low drug release rate without burst release on the profiles due to the high crystallinity in the fibre, but high drug release rate and burst release occurred on the release profiles of the solution electrospun fibres because of their low crystallinity, porous structure and roughness surface.

Polycaprolactone Microfibrous Scaffolds to Navigate Neural Stem Cells

Fibrous scaffolds have shown promise in tissue engineering due to their ability to improve cell alignment and migration. In this paper, poly(ε-caprolactone) (PCL) fibers are fabricated in different sizes using a microfluidic platform. By using this approach, we demonstrated considerable flexibility in ability to control the size of the fibers. It was shown that the average diameter of the fibers was obtained in the range of 2.6-36.5 μm by selecting the PCL solution flow rate from 1 to 5 μL min^-1 and the sheath flow rate from 20 to 400 μL min^-1 in the microfluidic channel. The microfibers were used to create 3D microenvironments in order to investigate growth and differentiation of adult hippocampal stem/progenitor cells (AHPCs) in vitro. The results indicated that the 3D topography of the PCL substrates, along with chemical (extracellular matrix) guidance cues supported the adhesion, survival, and differentiation of the AHPCs. Additionally, it was found that the cell deviation angle for 44-66% of cells on different types of fibers was less than 10°. This reveals the functionality of PCL fibrous scaffolds for cell alignment important in applications such as reconnecting serious nerve injuries and guiding the direction of axon growth as well as regenerating blood vessels, tendons, and muscle tissue.

Improved cellular infiltration in electrospun fiber via engineered porosity

Small pore sizes inherent to electrospun matrices can hinder efficient cellular ingrowth. To facilitate infiltration while retaining its extracellular matrix-like character, electrospinning was combined with salt leaching to produce a scaffold having deliberate, engineered delaminations. We made elegant use of a specific randomizing component of the electrospinning process, the Taylor Cone and the falling fiber beneath it, to produce a uniform, well-spread distribution of salt particles. After 3 weeks of culture, up to 4 mm of cellular infiltration was observed, along with cellular coverage of up to 70% within the delaminations. To our knowledge, this represents the first observation of extensive cellular infiltration of electrospun matrices. Infiltration appears to be driven primarily by localized proliferation rather than coordinated cellular locomotion. Cells also moved from the salt-generated porosity into the surrounding electrospun fiber matrix. Given that the details of salt deposition (amount, size, and number density) are far from optimized, the result provides a convincing illustration of the ability of mammalian cells to interact with appropriately tailored electrospun matrices. These layered structures can be precisely fabricated by varying the deposition interval and particle size conceivably to produce in vivo-like gradients in porosity such that the resulting scaffolds better resemble the desired final structure.