Visualization of porosity and pore size gradients in electrospun scaffolds using laser metrology.

We applied a recently developed method, laser metrology, to characterize the influence of collector rotation on porosity gradients of electrospun polycaprolactone (PCL) widely investigated for use in tissue engineering. The prior- and post-sintering dimensions of PCL scaffolds were compared to derive quantitative, spatially-resolved porosity 'maps' from net shrinkage. Deposited on a rotating mandrel (200 RPM), the central region of deposition reaches the highest porosity, ~92%, surrounded by approximately symmetrical decreases to ~89% at the edges.

Harnessing cortical plasticity via gabapentinoid administration promotes recovery after stroke.

Stroke causes devastating sensory-motor deficits and long-term disability due to disruption of descending motor pathways. Restoration of these functions enables independent living and therefore represents a high priority for those afflicted by stroke. Here, we report that daily administration of gabapentin, a clinically approved drug already used to treat various neurological disorders, promotes structural and functional plasticity of the corticospinal pathway after photothrombotic cortical stroke in adult mice.

Injectable, dispersible polysulfone-polysulfone core-shell particles for optical oxygen sensing.

Injectable sensors can significantly improve the volume of critical biomedical information emerging from the human body in response to injury or disease. Optical oxygen sensors with rapid response times can be achieved by incorporating oxygen-sensitive luminescent molecules within polymeric matrices with suitably high surface area to volume ratios. In this work, electrospraying utilizes these advances to produce conveniently injectable, oxygen sensing particles made up of a core-shell polysulfone-polysulfone structure containing a phosphorescent oxygen-sensitive palladium porphyrin species within the core.

Injectable biodegradable bi-layered capsule for sustained delivery of bevacizumab in treating wet age-related macular degeneration.

Vascular endothelial growth factor (VEGF) is a key regulator of abnormal blood vessel growth. As such, bevacizumab-based inhibition of VEGF has been the clinically adopted strategy to treat colorectal and breast cancers as well as age-related macular degeneration (AMD). However, as the treatment of vascular diseases often requires a high drug concentration for a long period, the burst release of bevacizumab remains a critical limitation in anti-VEGF-based therapies.

Modulation of biomimetic mineralization of collagen by soluble ectodomain of discoidin domain receptor 2.

Collagen fibrils serve as the major template for mineral deposits in both biologically derived and engineered tissues. In recent years certain non-collagenous proteins have been elucidated as important players in differentially modulating intra vs. extra-fibrillar mineralization of collagen.

Effect of Electrospun Fiber Mat Thickness and Support Method on Cell Morphology.

Electrospun fiber mats (EFMs) are highly versatile biomaterials used in a myriad of biomedical applications. Whereas some facets of EFMs are well studied and can be highly tuned (e.g.

Sintered electrospun polycaprolactone for controlled model drug delivery.

Electrospinning has been used widely for drug delivery applications due to its versatility and ease of modification of spun fiber properties. Net drug loading and release is typically limited by the inherent surface-area of the sample. In a relatively novel approach, sintering of electrospun fiber was used to create a capsule favoring long-term delivery.

Comparison of polyglycolic acid, polycaprolactone, and collagen as scaffolds for the production of tissue engineered intestine.

Cell-seeded scaffolds play critical roles in the production of tissue engineered intestine (TEI), a potential strategy for the treatment of short bowel syndrome. The current study compares polyglycolic acid (PGA), polycaprolactone (PCL), and collagen as scaffolds for TEI production. Tubular PGA scaffolds were prepared from nonwoven BIOFELT .

Understanding drug release from PCL/gelatin electrospun blends.

Electrospinning is one of the efficient processes to fabricate polymeric fibrous scaffolds for several biomedical applications. Several studies have published to demonstrate drug release from electrospun scaffolds. Blends of natural and synthetic electrospun fibers provide excellent platform to combine mechanical and bioactive properties.

Nanoscale upconversion for oxygen sensing.

Optical oxygen sensors have many promising qualities but rely on excitation by violet or blue wavelengths that suffer from high levels of scattering and absorption in biological tissues. Here we demonstrate an alternative method using 980nm near-infrared light to initially stimulate ceramic upconverting nanoparticles (UCNPs) contained within a novel form, electrospun core-shell fibers. The emission of the UCNPs excites a molecular optical oxygen sensor, the subsequent phosphorescent emission being dynamically quenched by the presence of molecular oxygen.

Biomimetic microstructural reorganization during suture retention strength evaluation of electrospun vascular scaffolds.

Suture retention strength (SRS) is commonly used as a measure the ability of sutures to adhere implants to surrounding tissue. While SRS is widely employed, surprisingly its effects on graft microstructure have not been characterized. This is particularly germane to the broad utilization of electrospun implants in tissue engineering.

Surface topography during neural stem cell differentiation regulates cell migration and cell morphology.

We sought to determine the contribution of scaffold topography to the migration and morphology of neural stem cells by mimicking anatomical features of scaffolds found in vivo. We mimicked two types of central nervous system scaffolds encountered by neural stem cells during development in vitro by constructing different diameter electrospun polycaprolactone (PCL) fiber mats, a substrate that we have shown to be topographically similar to brain scaffolds. We compared the effects of large fibers (made to mimic blood vessel topography) with those of small-diameter fibers (made to mimic radial glial process topography) on the migration and differentiation of neural stem cells.

HB-EGF embedded in PGA/PLLA scaffolds via subcritical CO2 augments the production of tissue engineered intestine.

The ability to deliver sustained-release, biologically active growth factors through custom designed tissue engineering scaffolds at sites of tissue regeneration offers great therapeutic opportunity. Due to the short in vivo half-lives of most growth factors, it is challenging to deliver these proteins to sites of interest where they may be used before being degraded. The application of subcritical CO2 uses gas-phase CO2 at subcritical pressures ranging from 41 to 62 bar (595-913 PSI) which avoids foaming by reducing the amount of CO2 dissolved in the polymer and maintains completely reversible plasticization.

Ablation characteristics of electrospun core-shell nanofiber by femtosecond laser.

This study examined the femtosecond laser ablation properties of core and shell polymers their relationship to the ablation characteristics of core-shell nanofibers. The single-pulse ablation threshold of bulk polycaprolactone (PCL) was measured to be 2.12J/cm(2) and that of bulk polydimethylsiloxane (PDMS) was 4.

Nanofiber-based paramagnetic probes for rapid, real-time biomedical oximetry.

EPR (electron paramagnetic resonance) based biological oximetry is a powerful tool that accurately and repeatedly measures tissue oxygen levels. In vivo determination of oxygen in tissues is crucial for the diagnosis and treatment of a number of diseases. Here, we report the first successful fabrication and remarkable properties of nanofiber sensors for EPR-oximetry applications.

Cancer cell aggregate hypoxia visualized in vitro via biocompatible fiber sensors.

To fully understand biological behavior in vitro often dictates that oxygen be reported at either a local or a cellular level. Oxygen sensors based on the luminescent quenching of a specific form of electrospun fiber were developed for measurement of both gaseous and dissolved oxygen concentrations. Electrospinning was used to fabricate "core-shell" fiber configurations in which oxygen-sensitive transition-metal porphyrin complexes are embedded in an optically clear, gas permeable polycarbonate polymer 'core' while polycaprolactone provided a protective yet biocompatible 'shell'.

Bearing-Foreign Material Deposition on Retrieved Co-Cr Femoral Heads: Composition and Morphology.

Bearing-foreign material deposition onto a femoral head can occur from contact with an acetabular shell due to dislocation, reduction, or subluxation. The purpose of this study was to comprehensively characterize deposit regions on retrieved cobalt-chrome femoral heads from metal-on-polyethylene total hip arthroplasties that had experienced such adverse events. The morphology, topography, and composition of deposition regions were characterized using macrophotography, optical profilometry, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy.

Glioma-astrocyte interactions on white matter tract-mimetic aligned electrospun nanofibers.

Gliomas are highly invasive forms of brain cancer comprising more than 50% of brain tumor cases in adults, and astrocytomas account for ∼60-70% of all gliomas. As a result of multiple factors, including enhanced migratory properties and extracellular matrix remodeling, even with current standards of care, mean survival time for patients is only ∼12 months. Because glioblastoma multiforme (GBM) cells arise from astrocytes, there is great interest in elucidating the interactions of these two cell types in vivo.

Microscale Sensing of Oxygen via Encapsulated Porphyrin Nanofibers: Effect of Indicator and Polymer "Core" Permeability.

Biomimetic polymer nanofibers integrate sensing capabilities creating utility across many biological and biomedical applications. We created fibers consisting of either a poly(ether sulfone) (PES) or a polysulfone (PSU) core coated by a biocompatible polycaprolactone (PCL) shell to facilitate cell attachment. Oxygen sensitive luminescent probes Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) or Pd(II) meso-tetra(pentafluorophenyl)porphine (PdTFPP), were incorporated in the core via single-step coaxial electrospinning providing superior sensitivity, high brightness, linear response, and excellent stability.

Actin grips: circular actin-rich cytoskeletal structures that mediate the wrapping of polymeric microfibers by endothelial cells.

Interaction of endothelial-lineage cells with three-dimensional substrates was much less studied than that with flat culture surfaces. We investigated the in vitro attachment of both mature endothelial cells (ECs) and of less differentiated EC colony-forming cells to poly-ε-capro-lactone (PCL) fibers with diameters in 5-20 μm range ('scaffold microfibers', SMFs). We found that notwithstanding the poor intrinsic adhesiveness to PCL, both cell types completely wrapped the SMFs after long-term cultivation, thus attaining a cylindrical morphology.

Fabrication of functional nanofibers through post-nanoparticle functionalization.

A facile method is developed to functionalize nanofiber surfaces with nanoparticles (NPs) through dithiocarbamate chemistry. Gold nanoparticles (AuNPs) and quantum dots (QDs) are immobilized on the nanofiber surface. These surfaces provide scaffolds for further supramolecular functionalization, as demonstrated through the Förster resonance energy transfer (FRET) pairing of QD-decorated fibers and fluorescent proteins.

THA Retrievals: The Need to Mark the Anatomic Orientation of the Femoral Head.

The hypothesis of this study was that the rotational orientation of femoral head damage would greatly affect the volumetric wear rate of the opposing polyethylene (PE) liner. Damage on twenty retrieved cobalt-chromium femoral heads was simulated in a validated damage-feature-based finite element model. For each individual retrieval, the anatomic orientation of the femoral head about the femoral neck axis was systematically varied, in 30° increments.

Preferential, enhanced breast cancer cell migration on biomimetic electrospun nanofiber 'cell highways'.

Background: Aggressive metastatic breast cancer cells seemingly evade surgical resection and current therapies, leading to colonization in distant organs and tissues and poor patient prognosis. Therefore, high-throughput in vitro tools allowing rapid, accurate, and novel anti-metastatic drug screening are grossly overdue. Conversely, aligned nanofiber constitutes a prominent component of the late-stage breast tumor margin extracellular matrix.

Distinctive damage patterns on THA metal bearing surfaces: case studies.

Retrieval analysis of total joint arthroplasty components has primarily focused on assessing wear or other damage to polyethylene components. As damage to the opposing bearing surface can accelerate polyethylene wear and damage, and especially with the use of hard-on-hard articulations, retrieval analysis benefits from incorporating evaluation of hard bearing surfaces as well. The purpose of this study is to report six case studies of metal bearing surfaces with distinctive damage patterns, to interpret them in the context of adverse events plausibly responsible for their creation, and to suggest their likely clinical or scientific significance.

Hemoglobin regulates the migration of glioma cells along poly(ε-caprolactone)-aligned nanofibers.

Aligned fibers have been shown to facilitate cell migration in the direction of fiber alignment while oxygen (O2 )-carrying solutions improve the metabolism of cells in hypoxic culture. Therefore, U251 aggregate migration on poly(ε-caprolactone) (PCL)-aligned fibers was studied in cell culture media supplemented with the O2 storage and transport protein hemoglobin (Hb) obtained from bovine, earthworm and human sources at concentrations ranging from 0 to 5 g/L within a cell culture incubator exposed to O2 tensions ranging from 1 to 19% O2 . Individual cell migration was quantified using a wound healing assay.