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Enzyme-responsive hydrogels for biomedical applications
No full textThis chapter highlights recent developments in enzyme-responsive gels. The focus is on peptide-based small-molecule hydrogels, for biomedical applications. The use of enzymes in this context provides a powerful methodology for controlled assembly, taking advantage of both biological selectivity and catalytic amplification. The building blocks for self-assembly and basic design rules for small molecule peptide gelators are discussed first. This is followed by a discussion of key features of biocatalytic self-assembly of hydrogels, focusing on control of nanoscale organization and consequent function. Finally, the potential applications of the enzyme-responsive hydrogels as biomaterials are discussed in the areas of cell culture, drug delivery, biosensing, and control of cell fate
Challenges of Scale-up of Cell Separation and Purification Techniques
No full textThis chapter focuses on methodologies suitable for mammalian cell separation as opposed to purification of other biological entities like particles, proteins and non-mammalian cells. It describes reported separation methods that may lend themselves to large-scale cell separation. Resolution requirements for the separation platform will be largely dictated by the nature of the starting population. Open versus closed systems for cell processing refers to the extent to which cells are exposed to the ambient environment, with a 'closed' environment limited by the boundaries of the vessel or device the cells are contained in. Cell-based products create new issues for bio-production and processing, requiring a re-think of current manufacturing strategy. The health economics of cell production and the therapeutic efficacy of the therapy on which it is based must be competitive with existing non-cellular treatments or management of a disease and its symptoms.</p
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Microencapsulation of probiotic bacteria into alginate hydrogels
No full textMechanical characterization of hydrogels and its implications for cellular activities
Get PDFHydrogels are viscoelastic materials routinely used for the development of culture models in tissue engineering and regenerative medicine. They act as a temporary matrix, providing topographical, biochemical, and biophysical cues which cells can remodel and develop into a tissue. The mechanical properties of the hydrogel mutually affect the construct and the cells alike. It is important to determine and monitor a construct's material properties in order to recapitulate the in vivo environment, which usually involves strategies aimed at improving the mechanical properties. The mechanical properties of soft tissues are closely related to their physiological function and so can act as cellular biomarkers. Time, culture, and conditioning environments can all influence the structural and biochemical aspects of the tissue, which are important to their performance and durability, ultimately dictating whether the construct will be successful or not in a given application. This chapter begins with the discussion of current characterization tools for hydrogel mechanical properties with the focus on non-destructive testing modalities. How mechanical properties can become a biomarker in regenerative medicine has been demonstrated through corneal stromal and ageing models. Various strategies for improving and tailoring the mechanical properties of hydrogels are discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Approaches to Corneal Tissue Engineering: Top-down or Bottom-up?
No full textAbstractTissue engineering creates biological tissues that aim to improve the function of diseased or damaged tissues such as the cornea (the main refractive component of the eye). Traditional tissue engineering strategies employ a “top-down” approach, in which cells are seeded on a polymeric scaffold that they then populate and create the appropriate extracellular matrix (ECM) often with the aid of perfusion, growth factors and/or mechanical stimulation. However, in highly organised tissues, such as the cornea, top-down approaches have difficulty recreating intricate but necessary microstructural features.With the desire to create more complex corneal tissues with features such as anisotropic hierarchical molecular assemblies, appropriate mechanical properties, cell binding motifs and corneal specific morphology, we are developing tissue engineering techniques that are moving away from the traditional top-down approach and instead focusing on building modular micro-tissues with repeated functional units which facilitate a bottom-up approach.Here we report on the success and shortcomings of both top-down and bottom-up approaches to creating engineered corneal tissues. Specifically, we will discuss recent work demonstrating the importance of engineering corneal ECM with appropriate levels of tissue compliance using a top-down approach. We will then highlight a bottom-up approach, which focuses on fabricating discreet bio-prosthetic ECM building blocks (corneal lamellae) with specific micro-architectural features derived solely from human corneal keratocytes under serum free conditions using enzyme responsive templates. These building blocks will then be used to generate a whole cornea whilst maintaining the intricate architecture and complexity of native corneal ECM
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