Nanoscale Displacements Detected by Evanescent Optical Coupling from an Optical Fiber to a Si Cantilever
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Aligned Growth of Stem Cells Derived from Ceria/PLGA Composite Tissue engineering continues to be a field of great interest due to its tremendous biomedical implications. In particular, hybrid organic–inorganic materials show great promise for tailoring biocompatibility, mechanical and electrical properties to a greater extent than the commonly used biopolymers alone. Cerium oxide (CeO2), or ceria, is known for its ability to quench free radicals, and it acts as an antioxidant by converting Ce3+ to Ce4+ in the presence of oxygen radicals. It is known that free radical formation can hinder biological cell proliferation, which is a requisite for tissue engineering. In the May 25 issue of Advanced Functional Materials (DOI: 10.1002/ adfm.200902363; p. 1617), E. Traversa and C. Mandoli of the National Institute for Materials Science, Japan; F. Pagliari of the University of Rome Tor Vergata, Italy; and their colleagues report the aligned growth of murine-derived cardiac and mesenchymal adult stem cells on a ceria/PLGA (poly(D,L-lactic-co-glycolic acid) biopolymer) hybrid composite substrate. Mesenchymal stem cells are multipotent stem cells that have been shown to differentiate into bone cells, cartilage cells, and fat cells. The researchers used patterned molds for solvent casting of the ceria/PLGA films. Ceria nanoparticles (5–8 nm grain size) were aligned along parallel lines, both straight and spirally grooved, to evaluate the orientation of the ceramic on cell growth. Nano-ceria with weight percent amounts of 0, 5, 10, and 20 were used. Nanocomposites with randomly oriented ceria nanoparticles were also formed as a control. These hybrid composites were
Nanoscale Displacements Detected by Evanescent Optical Coupling from an Optical Fiber to a Si Cantilever Mechanical displacements at the nanoscale are often measured by optical interferometry that requires the use of a coherent light source. Using non-interferometric techniques, such as beam deflection, allows the ability to relax this constraint. Recently, O. Basarir, K.L. Ekinci, and their colleagues at Boston University accurately measured displacements of a silicon microcantilever due to its evanescent optical coupling to a weakly guided mode of a silica optical fiber taper placed in its vicinity. As described in the June 1 issue of Optics Letters (DOI: 10.1364/OL.35.001792; 486
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Figure 1. Murine-derived cardiac stem cell grafts produced after 6 days in vitro over spirally pre-patterned composites. The images were acquired after (a) F-actin (red) and (b) nuclei (blue) stain under immunofluorescence and refer to 10 wt% CeO2/PLGA seeded composites. Reproduced with permission from Advanced Functional Materials 20 (10) (2010) 1617; DOI: 10.1002/adfm.200902363. © 2010 Wiley-VCH.
then examined for cell adhesion, growth, and proliferation using the stem cells. After three days in vitro (DIV) culturing, coverage of the scaffold surfaces with healthy cells was observed, with the cells growing in an aligned fashion following the ceria nanoparticles pattern; no alig
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