Microfiber Meshes Research Articles

Fabrication of 3D engineered intestinal tissue producing abundant mucus by air–liquid interface culture using paper-based dual-layer scaffold

Fabrication of engineered intestinal tissues with the structures and functions as humans is crucial and promising as the tools for developing drugs and functional foods. The aim of this study is to fabricate an engineered intestinal tissue from Caco-2 cells by air–liquid interface culture using a paper-based dual-layer scaffold and analyze its structure and functions. Just by simply placing on a folded paper soaked in the medium, the electrospun gelatin microfiber mesh as the upper cell adhesion layer of the dual-layer scaffold was exposed to the air, while the lower paper layer worked to preserve and supply the cell culture medium to achieve stable culture over several weeks. Unlike the flat tissue produced using the conventional commercial cultureware, Transwell, the engineered intestinal tissue fabricated in this study formed three-dimensional villous architectures. Microvilli and tight junction structures characteristic of epithelial tissue were also formed at the apical side. Furthermore, compared to the tissue prepared by Transwell, mucus production was significantly larger, and the enzymatic activities of drug metabolism and digestion were almost equivalent. In conclusion, the air–liquid interface culture using the paper-based dual-layer scaffold developed in this study was simple but effective in fabricating the engineered intestinal tissue with superior structures and functions.

DNA data storage in electrospun and melt-electrowritten composite nucleic acid-polymer fibers

Incorporating biomolecules as integral parts of computational systems represents a frontier challenge in bio- and nanotechnology. Using DNA to store digital data is an attractive alternative to conventional information technologies due to its high information density and long lifetime. However, developing an adequate DNA storage medium remains a significant challenge in permitting the safe archiving and retrieval of oligonucleotides. This work introduces composite nucleic acid-polymer fibers as matrix materials for digital information-bearing oligonucleotides. We devised a complete workflow for the stable storage of DNA in PEO, PVA, and PCL fibers by employing electrohydrodynamic processes to produce electrospun nanofibers with embedded oligonucleotides. The on-demand retrieval of messages is afforded by non-hazardous chemical treatment and subsequent PCR amplification and DNA sequencing. Finally, we develop a platform for melt-electrowriting of polymer-DNA composites to produce microfiber meshes of programmable patterns and geometries.

Convergence of melt electrowriting and extrusion-based bioprinting for vascular patterning of a myocardial construct

To progress cardiac tissue engineering strategies closer to the clinic, thicker constructs are required to meet the functional need following a cardiac event. Consequently, pre-vascularization of these constructs needs to be investigated to ensure survival and optimal performance of implantable engineered heart tissue. The aim of this research is to investigate the potential of combining extrusion-based bioprinting (EBB) and melt electrowriting for the fabrication of a myocardial construct with a precisely patterned pre-vascular pathway. Gelatin methacryloyl (GelMA) was investigated as a base hydrogel for the respective myocardial and vascular bioinks with collagen, Matrigel and fibrinogen as interpenetrating polymers to support myocardial functionality. Subsequently, extrusion-based printability and viability were investigated to determine the optimal processing parameters for printing into melt electrowritten meshes. Finally, an anatomically inspired vascular pathway was implemented in a dual EBB set-up into melt electrowritten meshes, creating a patterned pre-vascularized myocardial construct. It was determined that a blend of 5% GelMA and 0.8 mg·ml−1 collagen with a low crosslinked density was optimal for myocardial cellular arrangement and alignment within the constructs. For the vascular fraction, the optimized formulation consisted of 5% GelMA, 0.8 mg·ml−1 collagen and 1 mg·ml−1 fibrinogen with a higher crosslinked density, which led to enhanced vascular cell connectivity. Printability assessment confirmed that the optimized bioinks could effectively fill the microfiber mesh while supporting cell viability (∼70%). Finally, the two bioinks were applied using a dual EBB system for the fabrication of a pre-vascular pathway with the shape of a left anterior descending artery within a myocardial construct, whereby the distinct cell populations could be visualized in their respective patterns up to D14. This research investigated the first step towards developing a thick engineered cardiac tissue construct in which a pre-vascularization pathway is fabricated within a myocardial construct.

MIL-101-NH2(Fe)-Coated Nylon Microfibers for Immobilized Photocatalysts in RhB and Cr(VI) Removal.

MIL-101-NH2(Fe) is one of the effective photocatalytic metal-organic frameworks (MOFs) working under visible light. However, its powder-type form inhibits reusability in practical applications. In this study, we immobilized MIL-101-NH2(Fe) on a polymeric microfiber mesh to improve reusability while minimizing the loss of catalytic performance. To overcome the lack of surface functionality of the nylon fibers, an atomic layer deposition Al2O3 layer and NH2-BDC linker were introduced to facilitate uniform coating of the MOF on the fiber surface. The reactions of the metal precursor to the nylon substrate and NH2-BDC ligand of the MOF allow chemical bonding from the core to the shell of the entire hybrid catalytic materials. The resulting fiber-immobilized MOFs (Nylon@Al2O3@MOF) demonstrated high photocatalytic performance in the removal of RhB and Cr(VI) as representatives of organic dyes and heavy metals, respectively, while retaining over 85% of its efficiency after five cycles.

Covalent Protein Immobilization on 3D‐Printed Microfiber Meshes for Guided Cartilage Regeneration

AbstractCurrent biomaterial‐based strategies explored to treat articular cartilage defects have failed to provide adequate physico‐chemical cues in order to guide functional tissue regeneration. Here, it is hypothesized that atmospheric‐pressure plasma (APPJ) treatment and melt electrowriting (MEW) will produce microfiber support structures with covalently‐immobilized transforming growth factor beta‐1 (TGFβ1) that can stimulate the generation of functional cartilage tissue. The effect of APPJ operational speeds to activate MEW polycaprolactone meshes for immobilization of TGFβ1 is first investigated and chondrogenic differentiation and neo‐cartilage production are assessed in vitro. All APPJ speeds test enhanced hydrophilicity of the meshes, with the slow treatment speed having significantly less CC/CH and more COOH than the untreated meshes. APPJ treatment increases TGFβ1 loading efficiency. Additionally, in vitro experiments highlight that APPJ‐based TGFβ1 attachment to the scaffolds is more advantageous than direct supplementation within the medium. After 28 days of culture, the group with immobilized TGFβ1 has significantly increased compressive modulus (more than threefold) and higher glycosaminoglycan production (more than fivefold) than when TGFβ1 is supplied through the medium. These results demonstrate that APPJ activation allows reagent‐free, covalent immobilization of TGFβ1 on microfiber meshes and, importantly, that the biofunctionalized meshes can stimulate neo‐cartilage matrix formation. This opens new perspectives for guided tissue regeneration.

Melt Electrowriting Ordered TPU Microfibrous Mesh for On-Demand Colorimetric Wearable Sweat Detection

Fabric-based sweat sensors based on colorimetric analysis have the characteristics of simple structure, small size, convenience, and comfort, which are more suitable for vigorous exercise. However, the realization of on-demand detection of colorimetric sweat sensors is difficult. It will be invalid immediately once the detection process is activated, which may easily lead to ineffective detection. Therefore, the design and controllable fabrication of the sweat sampling layer is the key to improving the practicality of colorimetric sweat sensors. In this article, the hydrophobic thermoplastic polyurethane (TPU) flexible microfibrous mesh was controllably constructed by melt electrowriting and used as a sweat sampling layer to realize on-demand detection of colorimetric sweat sensor. The gating of different amounts of water can be achieved by precisely and orderly depositing the TPU microfiber meshes with different pore sizes and stacking layer numbers. Simultaneously, the optimal parameters of the TPU mesh were determined by the calibration experiment of the running test, which greatly improved the use efficiency (22 times) of the colorimetric sweat sensor.Moreover, the stability of the optimal sweat sensor was improved by 418% compared with the unoptimized one. The comfort and applicability of wearable sweat sensors in vigorous sports can be enhanced greatly by the controllable preparation of the TPU flexible microfiber meshes, which is helpful to promote the development of sweat sensors.

Characterizing the Effect of Adding Boron Nitride Nanotubes on the Mechanical Properties of Electrospun Polymer Nanocomposite Microfibers Mesh.

Electrospun fibrous meshes have a variety of applications such as filtration, drug delivery, energy storage, and engineered tissues due to their high surface area to mass ratio. Therefore, understanding the mechanical properties of these continuously evolving meshes is critical to expand and improve their performance. In this study, the effect of adding Boron Nitride Nanotube (BNNT) to Polymethylmethacrylate (PMMA) composite meshes on the mechanical properties of the polymer is studied. Electrospinning is used to fabricate microfiber meshes of PMMA and BNNT-PMMA. The fabricated meshes are tested experimentally with a uniaxial tensile tester. In addition, a theoretical model is introduced to investigate the effect of the number of fibers and the diameter of fiber inside the mesh on Young’s Modulus and Tensile Strength of the PMMA mesh. By adding 0.5% BNNT to the PMMA, Young’s Modulus and Tensile Strength of the PMMA mesh improved by 62.4% and 9.3%, respectively. Furthermore, simulated results show enhanced mesh properties when increasing the number of fibers and the single fiber diameter inside the mesh. The findings of this study help in understanding the mechanical properties of the nanocomposite electrospun meshes which expands and improves its utilization in different applications.

Directional Transportation in a Self-Pumping Dressing Based on a Melt Electrospinning Hydrophobic Mesh.

Self-pumping wound dressings with directional water transport ability have been widely studied for their function of directional extraction of excessive biofluid from wounds while keeping the wound in a moderately humid environment to realize rapid wound healing. However, the existing solutions have not paid close attention to the fabrication of a nonirritating hydrophobic layer facing the wounds, which may cause irritation to wounds and thereby further worsen inflammation. Herein, a flexible and elastic thermoplastic polyurethane (TPU) hydrophobic microfiber mesh (TPU-HMM) produced by melt electrospinning (MES) is reported. The TPU-HMM was compounded to a hydrophilic nanofiber membrane, which was fabricated by blending with polyamide 6 and poly(ethylene glycol) (PA6-PEG) to form a composite self-pumping dressing, for which the breakthrough pressure in a reverse direction was 12.8 times than that in a positive direction and the forward water transmission rate was increased by 700%. It shows good directional water transport ability and is expected to absorb excessive biofluid of the wounds. This solvent-free and easy-process TPU-HMM provides a new strategy for the development of functional self-pumping textiles, and the solvent-free fabrication method for fibers, which eliminates the potential toxicity brought by solvent residues, offers more possibilities for its applications in biomedicine.

Cellulose-Derived Carbon Microfiber Mesh for Binder-Free Lithium-Sulfur Batteries.

The practical application of lithium-sulfur batteries (LSBs) has been impeded by several chronic problems related to the insulating nature of sulfur and lithium sulfide, in addition to the dissolution and diffusion of lithium polysulfides. In view of these problems, a large variety of carbonaceous materials have been employed to enhance the electronic conductivity of the cathode and/or sequester lithium polysulfides within conductive matrixes. Although they may exhibit impressive electrochemical performance, the fabrication of most carbon materials involves costly precursors and complicated procedures. Waste paper-the main constituent of municipal waste-is composed of carbohydrates, and can be an ideal precursor for carbon materials. Herein, carbon microfiber meshes (CMFMs) obtained by the pyrolysis of common filter paper in argon (A-CMFM) or ammonia (N-CMFM) were used to form sulfur cathodes. Compared with LSBs based on A-CMFM, those based on N-CMFM demonstrated higher specific capacity and better rate capability, with a capacity of 650 mA h g-1 at 0.2 C and 550 mA h g-1 at 0.5 C. This was owing to the strong immobilization of lithium polysulfides resulting from the heteroatom doping and hydrophilicity of N-CMFM. The results indicate that cellulose paper-derived carbon is a promising candidate for application in high-performance LSBs.

Digital Design and Automated Fabrication of Bespoke Collagen Microfiber Scaffolds.

A great variety of natural and synthetic polymer materials have been utilized in soft tissue engineering as extracellular matrix (ECM) materials. Natural polymers, such as collagen and fibrin hydrogels, have experienced especially broad adoption due to the high density of cell adhesion sites compared to their synthetic counterparts, ready availability, and ease of use. However, these and other hydrogels lack the structural and mechanical anisotropy that define the ECM in many tissues, such as skeletal and cardiac muscle, tendon, and cartilage. Herein, we present a facile, low-cost, and automated method of preparing collagen microfibers, organizing these fibers into precisely controlled mesh designs, and embedding these meshes in a bulk hydrogel, creating a composite biomaterial suitable for a wide variety of tissue engineering and regenerative medicine applications. With the assistance of custom software tools described herein, mesh patterns are designed by a digital graphical user interface and translated into protocols that are executed by a custom mesh collection and organization device. We demonstrate a high degree of precision and reproducibility in both fiber and mesh fabrication, evaluate single fiber mechanical properties, and provide evidence of collagen self-assembly in the microfibers under standard cell culture conditions. This work offers a powerful, flexible platform for the study of tissue engineering and cell material interactions, as well as the development of therapeutic biomaterials in the form of custom collagen microfiber patterns that will be accessible to all through the methods and techniques described here.Impact StatementCollagen microfiber meshes have immediate and broad applications in tissue engineering research and show high potential for later use in clinical therapeutics due to their compositional similarities to native extracellular matrix and tunable structural and mechanical characteristics. Physical and biological characterizations of these meshes demonstrate physiologically relevant mechanical properties, native-like collagen structure, and cytocompatibility. The methods presented herein not only describe a process through which custom collagen microfiber meshes can be fabricated but also provide the reader with detailed device plans and software tools to produce their own bespoke meshes through a precise, consistent, and automated process.

Design and assessment of a flexible fish robot actuated by shape memory alloys

In this paper, we present a fish-like underwater robot inspired by the black bass fish. This robot is composed of a deformable structure and muscle-like linear actuators based on shape memory alloy wires. Such actuators are used to bend a continuous structure representing the backbone of the fish. The prototype is also equipped with a bio-inspired synthetic skin made of liquid silicone rubber and Lycra microfiber mesh. We present the mechatronics of the prototype and its control scheme, which take advantage of flex sensors for proprioception. Experiments under different conditions (in air and in water) assess the effectiveness of the mechatronics design and demonstrate that a relatively simple PID controller provides high precision of the muscles’ position control. Here, the implementation of biomimetic kinematics and silent actuation technology in bio-inspired underwater robotics are demonstrated. Progress in this technology could provide multiple applications, including fish farming, coastal protection and live animal monitoring where silent robotics are necessary.

Antimicrobial activity of tellurium‐loaded polymeric fiber meshes

ABSTRACTA series of poly(methyl methacrylate) solutions loaded with varying concentrations of tellurium particles are prepared and processed into continuous and smooth microfiber meshes. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy are used to study the morphology and surface elemental composition of the composite fibers. Fiber diameters range between 7 and 14 µm with surface nanopores on the fibers ranging between 100 and 200 nm. Energy‐dispersive X‐ray spectroscopy confirmed successful incorporation of tellurium particles into the fibers. The concentration of tellurium in the composite significantly influenced fiber diameter, pore size, and morphology. The antibacterial activity of the prepared fibers is tested using Escherichia coli K12. The fibers are incubated in bacterial suspensions for 24 h at 37 °C and 150 rpm. Antibacterial activity is assessed through the colony‐counting method and is found to be dose dependent. The fibers with 4 wt % tellurium exhibited the most potent antibacterial properties as a 1.16 log reduction was observed. © 2018 The Authors. Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46368.

Nucleic acid scavenging microfiber mesh inhibits trauma-induced inflammation and thrombosis.

Trauma patients produce a host of danger signals and high levels of damage-associated molecular patterns (DAMPs) after cellular injury and tissue damage. These DAMPs are directly and indirectly involved in the pathogenesis of various inflammatory and thrombotic complications in patients with severe injuries. No effective therapeutic agents for the removal of DAMPs from blood or tissue fluid have been developed. Herein, we demonstrated that nucleic acid binding polymers, e.g., polyethylenimine (PEI) and polyamidoamine dendrimers, immobilized onto electrospun microfiber mesh can effectively capture various DAMPs, such as extracellular DNAs and high mobility group box 1 (HMGB1). Furthermore, treatment with PEI-immobilized microfiber mesh abrogated the ability of DAMPs, released from dead and dying cells in culture or found in patients following traumatic injury, to activate innate immune responses and coagulation invitro and invivo. Nucleic acid scavenging microfiber meshes represent an effective strategy to combat inflammation and thrombosis in trauma.

Polymer microfiber meshes facilitate cardiac differentiation of c-kit+ human cardiac stem cells

Electrospun microfiber meshes have been shown to support the proliferation and differentiation of many types of stem cells, but the phenotypic fate of c-kit+ human cardiac stem cells (hCSCs) have not been explored. To this end, we utilized thin (~5µm) elastomeric meshes consisting of aligned 1.7µm diameter poly (ester-urethane urea) microfibers as substrates to examine their effect on hCSC viability, morphology, proliferation, and differentiation relative to cells cultured on tissue culture polystyrene (TCPS). The results showed that cells on microfiber meshes displayed an elongated morphology aligned in the direction of fiber orientation, lower proliferation rates, but increased expressions of genes and proteins majorly associated with cardiomyocyte phenotype. The early (NK2 homeobox 5, Nkx2.5) and late (cardiac troponin I, cTnI) cardiomyocyte genes were significantly increased on meshes (Nkx=2.5 56.2±13.0, cTnl=2.9±0.56,) over TCPS (Nkx2.5=4.2±0.9, cTnl=1.6±0.5, n=9, p<0.05 for both groups) after differentiation. In contrast, expressions of smooth muscle markers, Gata6 and myosin heavy chain (SM-MHC), were decreased on meshes. Immunocytochemical analysis with cardiac antibody exhibited the similar pattern of above cardiac differentiation. We conclude that aligned microfiber meshes are suitable for guiding cardiac differentiation of hCSCs and may facilitate stem cell-based therapies for treatment of cardiac diseases.

Investigating the microenvironmental effects of scaffold chemistry and topology in human mesenchymal stromal cell/polymeric hollow microfiber constructs

Tissue engineering scaffolds have shown an intrinsic ability to provide cellular stimulation, thus behaving as physically active microenvironments. This study reports on the interaction between human mesenchymal stromal cells (hMSCs) and dry-wet spun polymer microfiber meshes. The following scaffolding parameters were tested: i) polymer type: poly-L-lactide (PLLA) vs poly-ε-caprolactone (PCL); ii) non-solvent type: ethanol (Et-OH) vs isopropanol/ gelatin; iii) scaffold layout: patterned vs random microfiber fabrics. After two culture weeks, the effects on metabolic activity, scaffold colonization and function of undifferentiated hMSCs were assayed. In our study, the polymer type affected the hMSC metabolic activity timeline, and the metabolic picks occurred earlier in PLLA (day 6) than in PCL (day 9) scaffolds. Instead, PLLA vs PCL had no endpoint effect on alkaline phosphatase (ALP) activity expression. On average, the hMSCs grown on all the random microfiber fabrics showed an ALP activity statistically superior to that detected on patterned microfiber fabrics, with the highest in Et-OH random subtypes. Such findings are suggestive of enhanced osteogenic potential. The understanding of scaffold-driven stimulation could enable environmental hMSC commitment, paving the way for new regenerative strategies.

Manufacturing and characterization of encapsulated microfibers with different molecular weight poly(ε-caprolactone) (PCL) resins using a melt electrospinning technique

Encapsulated structures of poly(ε-caprolactone) microfibers were successfully fabricated through two distinct melt electrospinning methods: melt coaxial and melt-blending electrospinning methods. Both methods resulted in encapsulated microfibers, but the resultant microfibers had different morphologies. Melt coaxial electrospinning formed a dual, semi-concentric structure, whereas melt-blending electrospinning resulted in an islands-in-a-sea fiber structure (i.e. a multiple-core structure). The encapsulated microfibers were produced using a custom-designed melt coaxial electrospinning device and the microfibers were characterized using a scanning electron microscope. To analyze the properties of the melt blended encapsulated fibers and coaxial fibers, the microfiber mesh specimens were collected. The mechanical properties of each microfiber mesh were analyzed through a tensile test. The coaxial microfiber meshes were post processed with a femtosecond laser machine to create dog-bone shaped tensile test specimens, while the melt blended microfiber meshes were kept as-fabricated. The tensile experiments undertaken with coaxial microfiber specimens resulted in an increase in tensile strength compared to 10 k and 45 k monolayer specimens. However, melt blended microfiber meshes did not result in an increase in tensile strength. The melt blended microfiber mesh results indicate that by using greater amounts of 45 k PCL resin within the microstructure, the resulting fibers obtain a higher tensile strength.

Poly(ε-caprolactone) Microfiber Meshes for Repeated Oil Retrieval.

Electrospun non-woven poly(ε-caprolactone) (PCL) microfiber meshes are described as biodegradable, mechanically robust, and reusable polymeric oil sorbents capable of selectively retrieving oil from simulated oil spills in both fresh and seawater scenarios. Hydrophobic PCL meshes have >99.5% (oil over water) oil selectivity and oil absorption capacities of ~10 grams of oil per gram of sorbent material, which is shown to be a volumetrically driven process. Both the oil selectivity and absorption capacity remained constant over several oil absorption and vacuum assisted retrieval cycles when removing crude oil or mechanical pump oil from deionized water or simulated seawater mixtures. Finally, when challenged with surfactant stabilized water-in-oil emulsions, the PCL meshes continued to show selective oil absorption. These studies add to the knowledge base of synthetic oil sorbents highlighting a need for biodegradable synthetic oil sorbents which balance porosity and mechanical integrity enabling reuse, allowing for the efficient recovery of oil after an accidental oil spill.

Processing large-diameter poly(L-lactic acid) microfiber mesh/mesenchymal stromal cell constructs via resin embedding: an efficient histologic method

In this study, we performed a complete histologic analysis of constructs based on large diameter ( > 100 μm) poly-L-lactic acid (PLLA) microfibers obtained via dry-wet spinning and rat Mesenchymal Stromal Cells (rMSCs) differentiated towards the osteogenic lineage, using acrylic resin embedding.In many synthetic polymer-based microfiber meshes, ex post processability of fiber/cell constructs for histologic analysis may face deterring difficulties, leading to an incomplete investigation of the potential of these scaffolds. Indeed, while polymeric nanofiber (fiber diameter = tens of nanometers)/cell constructs can usually be embedded in common histologic media and easily sectioned, preserving the material structure and the antigenic reactivity, histologic analysis of large polymeric microfiber/cell constructs in the literature is really scant. This affects microfiber scaffolds based on FDA-approved and widely used polymers such as PLLA and its copolymers. Indeed, for such constructs, especially those with fiber diameter and fiber interspace much larger than cell size, standard histologic processing is usually inefficient due to inhomogeneous hardness and lack of cohesion between the synthetic and the biological phases under sectioning.In this study, the microfiber/MSC constructs were embedded in acrylic resin and the staining/reaction procedures were calibrated to demonstrate the possibility of successfully employing histologic methods in tissue engineering studies even in such difficult cases. We histologically investigated the main osteogenic markers and extracellular matrix molecules, such as alkaline phosphatase, osteopontin, osteocalcin, TGF-β1, Runx2, Collagen type I and the presence of amorphous, fibrillar and mineralized matrix. Biochemical tests were employed to confirm our findings. This protocol permitted efficient sectioning of the treated constructs and good penetration of the histologic reagents, thus allowing distribution and expression of almost all the tested molecules to be revealed. Our results demonstrated that it is possible to perform histologic analyses of large-diameter PLLA-based microfiber scaffold/MSC constructs that face the failure of standard histologic procedures.

Immobilization of Heparan Sulfate on Electrospun Meshes to Support Embryonic Stem Cell Culture and Differentiation *

As our understanding of what guides the behavior of multi- and pluripotent stem cells deepens, so too does our ability to utilize certain cues to manipulate their behavior and maximize their therapeutic potential. Engineered, biologically functionalized materials have the capacity to influence stem cell behavior through a powerful combination of biological, mechanical, and topographical cues. Here, we present the development of a novel electrospun scaffold, functionalized with glycosaminoglycans (GAGs) ionically immobilized onto the fiber surface. Bound GAGs retained the ability to interact with GAG-binding molecules and, crucially, presented GAG sulfation motifs fundamental to mediating stem cell behavior. Bound GAG proved to be biologically active, rescuing the neural differentiation capacity of heparan sulfate-deficient mouse embryonic stem cells and functioning in concert with FGF4 to facilitate the formation of extensive neural processes across the scaffold surface. The combination of GAGs with electrospun scaffolds creates a biomaterial with potent applicability for the propagation and effective differentiation of pluripotent stem cells.

Fabrication and characterization of multiscale electrospun scaffolds for cartilage regeneration

Recently, scaffolds for tissue regeneration purposes have been observed to utilize nanoscale features in an effort to reap the cellular benefits of scaffold features resembling extracellular matrix (ECM) components. However, one complication surrounding electrospun nanofibers is limited cellular infiltration. One method to ameliorate this negative effect is by incorporating nanofibers into microfibrous scaffolds. This study shows that it is feasible to fabricate electrospun scaffolds containing two differently scaled fibers interspersed evenly throughout the entire construct as well as scaffolds containing fibers composed of two discrete materials, specifically fibrin and poly(ε-caprolactone). In order to accomplish this, multiscale fibrous scaffolds of different compositions were generated using a dual extrusion electrospinning setup with a rotating mandrel. These scaffolds were then characterized for fiber diameter, porosity and pore size and seeded with human mesenchymal stem cells to assess the influence of scaffold architecture and composition on cellular responses as determined by cellularity, histology and glycosaminoglycan (GAG) content. Analysis revealed that nanofibers within a microfiber mesh function to maintain scaffold cellularity under serum-free conditions as well as aid the deposition of GAGs. This supports the hypothesis that scaffolds with constituents more closely resembling native ECM components may be beneficial for cartilage regeneration.