Fabrication of a Simultaneous Highly Transparent and Highly Hydrophobic Fibrous Films

This paper discusses the fabrication and characterization of electrospun nanofiber scaffolds made of polystyrene (PS). The scaffolds were characterized in terms of their basis material molecular weight, fiber diameter distribution, contact angles, contact angle hysteresis, and transmittance. We propose an aligned electrospun fiber scaffold using an alignment tool (alignment jig) for the fabrication of highly hydrophobic (θW > 125°) and highly transparent (T > 80.0%) films. We fabricated the alignment jig to align the electrospun fibers parallel to each other. The correlation between the water contact angles and surface roughness of the aligned electrospun fibers was investigated. We found that the water contact angle increased as the surface roughness was increased. Therefore, the hydrophobic properties of the aligned electrospun fibers were enhanced by increasing the surface roughness. With the change in the electrospinning mode to produce aligned fibers rather than randomly distributed fibers, the transmittance of the aligned electrospun fibers increased. The increase in the porous area, leading to better light transmittance in comparison to randomly distributed light scattering through the aligned electrospun fibers increased with the fibers. Through the above investigation of electrospinning parameters, we obtained the simultaneous transparent (>80%) and hydrophobic (θW > 140°) electrospun fiber scaffold. The aligned electrospun fibers of PS had a maximum transmittance of 91.8% at the electrospinning time of 10 s. The water contact angle (WCA) of the aligned electrospun fibers increased from 77° to 141° as the deposition time increased from 10 s to 40 s. The aligned fibers deposited at 40 s showed highly hydrophobic characteristics (θW > 140°).

Fabrication of Polyurethane/Polylactide (PU/PLDL) Nanofibers Using Electrospinning Method

Polylactide and aliphatic polyurethane are biodegradable synthetic polymers which are broadly used as biomaterials in regenerative medicine for implants and scaffolds for tissue engineering. In this paper, the detailed studies of the fabrication of the electrospun fibers of polyurethane/polylactide mixtures were described. The influence of the used solvent (dimethylformamide (DMF)) and diluents (acetone and dichloromethane (DCM)) on the rheological parameters and electrospinning of the described mixtures was examined. Rheological studies showed that polyure-thane/polylactide mixtures have mostly non-Newtonian character, strongly influenced by the diluent. Solutions containing 50 wt.% or more of polyurethane became less viscous after the addition of DCM or acetone, whereas those with bigger amount of polylactide showed higher viscosity after the addition of DCM and lower viscosity after the addition of acetone. Optimized electrospinning process has been elaborated. Fibers with diameters from 250 nm up to 1 µm have been produced and compared. Pure acetone worsened the electrospinning process, but the more DCM was in the mixture, the thinner and more aligned fibers were produced.

Abstract 13026: Homogeneous 2D and 3D Alignment of Cardiomyocytes in Dilated Cardiomyopathy Revealed by Intravital Heart Imaging

Background: In contrast to hypertrophic cardiomyopathy, there has been reported no specific pattern of cardiomyocyte array in dilated cardiomyopathy (DCM). This might be because it is assessed only on heart tissue sections two-dimensionally (2D). To address this, we sought to evaluate cardiomyocyte alignment in DCM three-dimensionally (3D) using intravital heart imaging techniques. Methods and Results: We observed cardiomyocytes of membrane fluorescent reporter mice up to 100μm depth by an intravital imaging system with two-photon microscopy. On each 2D images taken at 1μm interval, the angles of cardiomyocytes from a vertical line were measured and their distribution was plotted. Then the plots of all layers were merged so that layer-to-layer change of angle distribution can be visualized. In these merged plots, cardiomyocytes exhibited several peaks with a certain spread around each peak, suggesting that cardiomyocytes change their alignments by every layer in 3D and position twistedly even in a single layer (Figure). We next assessed cardiac mutant Troponin T knock-in mice as a DCM model. The angle distribution in these mice was less various within a single layer and between layers as well. These results indicate that cardiomyocytes of DCM model mice align homogeneously both in 2D and in 3D. To determine how homogeneous alignment contributes to cardiomyocyte contractility, we captured the motion of cultured cardiomyocytes and found that cardiomyocytes seeded on the top of linearly aligned fibers show greater motion than those seeded on randomly aligned fibers. Conclusion: Using intravital imaging, we have provided a first evidence of cardiomyocyte array in 3D and demonstrated that cardiomyocytes of DCM model mice align homogeneously both in 2D and in 3D. Homogeneous alignment of those mice might be the consequences of impaired cardiac function as a way to increase let ventricular contractility.

Magnetic Fields Enable Precise Spatial Control of Electrospun Fiber Alignment for Fabricating Complex Gradient Materials

<div>Musculoskeletal interfacial tissues consist of complex gradients in structure, cell phenotype, and biochemical signaling that are important for function. Designing tissue engineering strategies to mimic these types of gradients is an ongoing challenge. In particular, new fabrication techniques that enable precise spatial control over fiber alignment are needed to better mimic the structural gradients present in interfacial tissues, such as the tendon-bone interface. Here, we report a modular approach to spatially controlling fiber alignment using magnetically-assisted electrospinning. Electrospun fibers were highly aligned in the presence of a magnetic field and smoothly transitioned to randomly aligned fibers away from the magnetic field. Importantly, magnetically-assisted electrospinning allows for spatial control over fiber alignment at sub-millimeter resolution along the length of the fibrous scaffold similar to the native structural gradient present in many interfacial tissues. The versatility of this approach was further demonstrated using multiple electrospinning polymers and different magnet configurations to fabricate complex fiber alignment gradients. As expected, cells seeded onto gradient fibrous scaffolds were elongated and aligned on the aligned fibers and did not show a preferential alignment on the randomly aligned fibers. Overall, this fabrication approach represents an important step forward in creating gradient fibrous materials and are promising as tissue-engineered scaffolds for regenerating functional musculoskeletal interfacial tissues. <br></div>

Magnetic Fields Enable Precise Spatial Control of Electrospun Fiber Alignment for Fabricating Complex Gradient Materials

<div>Musculoskeletal interfacial tissues consist of complex gradients in structure, cell phenotype, and biochemical signaling that are important for function. Designing tissue engineering strategies to mimic these types of gradients is an ongoing challenge. In particular, new fabrication techniques that enable precise spatial control over fiber alignment are needed to better mimic the structural gradients present in interfacial tissues, such as the tendon-bone interface. Here, we report a modular approach to spatially controlling fiber alignment using magnetically-assisted electrospinning. Electrospun fibers were highly aligned in the presence of a magnetic field and smoothly transitioned to randomly aligned fibers away from the magnetic field. Importantly, magnetically-assisted electrospinning allows for spatial control over fiber alignment at sub-millimeter resolution along the length of the fibrous scaffold similar to the native structural gradient present in many interfacial tissues. The versatility of this approach was further demonstrated using multiple electrospinning polymers and different magnet configurations to fabricate complex fiber alignment gradients. As expected, cells seeded onto gradient fibrous scaffolds were elongated and aligned on the aligned fibers and did not show a preferential alignment on the randomly aligned fibers. Overall, this fabrication approach represents an important step forward in creating gradient fibrous materials and are promising as tissue-engineered scaffolds for regenerating functional musculoskeletal interfacial tissues. <br></div>

Electrospinning of Cellulose Nanocrystal-Reinforced Polyurethane Fibrous Mats

We report the electrospinning of mechanically-tunable, cellulose nanocrystal (CNC)-reinforced polyurethanes (PUs). Using high-aspect ratio CNCs from tunicates, the stiffness and strength of electrospun PU/CNC mats are shown to generally increase. Furthermore, by tuning the electrospinning conditions, fibrous PU/CNC mats were created with either aligned or non-aligned fibers, as confirmed by scanning electron microscopy. PU/CNC mats having fibers aligned in the strain direction were stiffer and stronger compared to mats containing non-aligned fibers. Interestingly, fiber alignment was accompanied by an anisotropic orientation of the CNCs, as confirmed by wide-angle X-ray scattering, implying their alignment additionally benefits both stiffness and strength of fibrous PU/CNC nanocomposite mats. These findings suggest that CNC alignment could serve as an additional reinforcement mechanism in the design of stronger fibrous nanocomposite mats.

Polarized blue photoluminescence of mesoscopically ordered electrospun non-conjugated polyacrylonitrile nanofibers

Electrospun fibres from the non-conjugated polymer polyacrylonitrile are aligned by heat-stretching. These aligned fibers emit polarized blue fluorescence and green phosphorescence.