123 research outputs found
Influence of variable substrate geometry on wettability and cellular responses
No full textIn this report, we evaluate the impact of a systematic change to the extracellular environment on cell morphology and functionality by combining the inherent properties of biocompatible polymers such as polydimethylsiloxane and polycaprolactone with a specific surface response. By microstructuring pillars and pits on the substrates, varying spacing and height of the structures, we investigate the role of topography in fibroblast cell adhesion and viability. The change of wetting behaviour was tailored and evaluated in terms of contact angle measurements. It was shown that the range of micro-scale physical cues at the interface between the cells and the surrounding environment affects cell shape and migrations, indicating a tendency to respond differently to higher features of the micro-scale. We found that surface topography seems dominant over material wettability, fibroblasts responded to variations in topography by altering morphology and migrating along the direction of spacing among the features biased by the height of structures and not by the material. It is therefore possible to selectively influence either cell adhesion or morphology by choosing adequate topography of the surface. This work can impact in the design of biomaterials and can be applied to implanted biomedical devices, tissue engineering scaffolds and lab on chip devices
Superhydrophobicity and Superhydrophilicy of Regular Nanopatterns
No full textThe hydrophilicity, hydrophobicity, and sliding behaviour of water droplets on nanoasperities of controlled dimensions were investigated experimentally. We show that the "hemi-wicking"theory for hydrophilic SiO2 samples successfully predicts the experimental advancing angles and that the same patterns, after silanization, become superhydrophobic in agreement with the Cassie-Baxter and Wenzel theories. Our model tophographies have the same dimensional scale of some naturally occurring structures that exhibit similar wetting properties. Our results confirm that a forest of hydrophilic/hydrophobic slender pillars is the most effective superwettable/water-repellent configuration. It is shown that the shape and curvature of the edges of the aspertieis play an important role in determining the advancing angles
Air-trapping on biocompatible nanopatterns
No full textThe occurrence of air-trapping inside poly-eta-caprolactone nanopits was investigated by measuring the contact angles of water droplets on a set of defined nanotopographies. It is shown that the advancing angles follow the Cassie-Baxter theory, thus revealing the presence of air bubbles inside the biodegradable nanopatterns. The importance of these observations for the definition of hydrophilicity/hydrophobicity and in the context of in vitro cell behavior is discussed
Mechanical gradient cues for guided cell motility and control of cell behavior on uniform substrates
No full textA novel method for the fabrication and the use of simple uniform poly(dimethylsiloxane) PDMS substrates for controlling cell motility by a mechanical gradient is reported. The substrate is fabricated in PDMS using soft lithography and consists of a soft membrane suspended on top of a patterned PDMS substrate. The difference in the gradient stiffness is related to the underlying pattern. It is shown experimentally that these uniform substrates can modulate the response of cell motility, thus enabling patterning on the surfaces with precise cell motility. Because of the uniformity of the substrate, cells can spread equally and a directional movement to stiffer regions is clearly observed. Varying the geometry underlying the membrane, cell patterning and movement can be quantitatively characterized. This procedure is capable of controlling cell motility with high fidelity over large substrate areas. The most significant advance embodied in this method is that it offers the use of mechanical features to control cell adhesion and not topographical or chemical variations, which has not been reported so far. This modulation of the response of cell motility will be useful for the design and fabrication of advanced planar and 3D biological assemblies suitable for applications in the field of biotechnology and for tissue-engineering purposes
Undergraduate researchers report only moderate knowledge of scholarly communication: they must be offered more support
No full textUndergraduate students are increasingly participating in the scholarly communication process, mostly through formal research experiences. However, Catherine Fraser Riehle and Merinda Kaye Hensley, having surveyed and interviewed university students, reveal that undergraduate researchers have only moderate levels of confidence in their knowledge of scholarly communications, especially publication and access models, author and publisher rights, determining the impact of research, and research data management. Moreover, students revealed that to receive specific guidance in these areas was rare. There is much opportunity for faculty members, graduate students, librarians, and research programme coordinators to collaborate and develop learning interventions in these areas
The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder
No full textA key tenet of bone tissue engineering is the development of scaffold materials that can stimulate stem cell differentiation in the absence of chemical treatment to become osteoblasts without compromising material properties. At present, conventional implant materials fail owing to encapsulation by soft tissue, rather than direct bone bonding. Here, we demonstrate the use of nanoscale disorder to stimulate human mesenchymal stem cells (MSCs) to produce bone mineral in vitro, in the absence of osteogenic supplements. This approach has similar efficiency to that of cells cultured with osteogenic media. In addition, the current studies show that topographically treated MSCs have a distinct differentiation profile compared with those treated with osteogenic media, which has implications for cell therapies.<br/
Microcontact printing of fibronectin on a biodegradable polymeric surface for skeletal muscle cell orientation
No full textBACKGROUND AND OBJECTIVES:</b> Micropatterning and microfabrication techniques have been widely used to control cell adhesion and proliferation along a preferential direction according to contact guidance theory. One of these techniques is microcontact printing, a soft lithographic technique based on the transfer of a "molecular ink" from an elastomeric stamp to a surface. This method allows the useful attachment of biomolecules in a few seconds on a variety of surfaces with sub-micrometer resolution and control, without modifying the biomolecule properties. The aim of this study is to develop an easy and versatile technique for in vitro production of arrays of skeletal muscle myofibers using microcontact printing technique on biodegradable substrata.
METHODS: Microcontact printing of fibronectin stripes (10, 25, 50 μm in width) was performed onto biodegradable L-lactide/trimethylene carbonate copolymer (PLLA-TMC) films. C2C12, a murine myoblast cell line, was used for the production of parallel myofibers.
RESULTS: This approach proved to be simple, reliable and effective in obtaining a stable pattern of fibronectin on the PLLA-TMC surface as observed by fluorescence microscopy. C2C12 cells were well aligned along the pattern 24 hours after seeding, especially on fibronectin stripes 10 and 25 μm in width. Seven days after confluence cells fused and formed aligned multinucleated cells expressing a-actinin.
CONCLUSIONS: Fibronectin patterning seems to be a useful method to induce cell alignment and to improve myotube formation. Further studies will be focused on the possibility of applying external stimuli to these structures to obtain healthy myotubes and to induce myofiber development
Developing Core Leadership Competencies for the Library Profession
No full textThe development of competencies, competency lists, or competency models has become a popular way to assess the strengths, needs, and potential contributions of individuals in an organization. The success of libraries as organizations is determined by the actions of the individuals who work in those libraries; the success of those individuals in carrying out the missions of those libraries is in large measure a reflection of the type and quality of leadership. Successful library leaders demonstrate certain skills that are instrumental in the delivery of desired outcomes. We usually think of the demonstration of these skills as competencies.
Creating a list of competencies for library leaders is a key objective envisioned in the strategic plan of the Library Leadership Administration and Management Association (LLAMA). This task was assigned to five members of the 2008 class of the American Library Association’s Emerging Leaders Program. The project is a critical first step toward a list of competencies or standards that would serve at least three types of users: library educators planning curricula, aspiring library leaders hoping to advance their careers, and experienced library leaders seeking to advance the profession. This article will provide an overview of the library literature addressing competency models, describe the process used to develop the competency model for library leadership, review competency models found in the literature of other professions, and discuss the proposed core competency model for leadership in our profession
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