Surface coated Eu(OH)3 nanorods: a facile synthesis, characterization, MR relaxivities and in vitro cytotoxicity.

The water-soluble and biocompatible D-glucuronic acid coated Eu(OH)3 nanorods (average thickness x average length = 9.0 x 118.3 nm) have been prepared in one-pot synthesis. The D-glucuronic acid coated Eu(OH)3 nanorods showed a strong fluorescence at approximately 600 nm with a narrow emission band width. A cytotoxicity test by using DU145 cells showed that D-glucuronic acid coated Eu(OH)3 nanorods are not toxic up to 100 microM, making them a promising candidate for biomedical applications such as fluorescent imaging. The minimum Eu concentration needed for a conventional confocal imaging was estimated to be approximately 0.1 mM. Therefore, D-glucuronic acid coated Eu(OH)3 nanorods can be applied to fluorescent imaging. However, a very tiny magnetization of approximately 1.2 emu/g at room temperature and at an applied field of 5 tesla was observed. As a result, very small r1 and r2 water proton relaxivities were estimated, implying that surface coated Eu(OH)3 nanorods are not sufficient for MRI contrast agents.

Implications of the oxygenated electrospun poly(ɛ-caprolactone) nanofiber for the astrocytes activities.

Astrocytes support structure of central nervous system (CNS) and provide nutrients to neurons. When CNS is injured, astrocytes are activated and produce glia scar. There are debates if the reactive astrocytes give beneficial or harmful effects on neuronal regeneration. In vitro tissue culture systems successfully have been used to investigate how the astrocytes activity is regulated in response to environmental conditions. Physicochemical characteristics of supporting materials for tissue culture are one of the most important environmental conditions. Electrospun nanofiber has physical uniqueness such as high surface area to volume ratio and high porosity, which is favorable to tissue culture. However, cellular activities can also be regulated in response to surface chemistry, which can be modified easily and diversely. Poly(ε-caprolactone) (PCL) is widely used for a scaffold for tissue culture. In this research, oxygen plasma-treated PCL nanofiber was assessed to ascertain whether it can have such potentials to regulate astrocytes activity. As a result, oxygen plasma treatment increased the hydrophilicity of the PCL nanofiber which made adhesion and viability of astrocytes enhanced without cytotoxicity Activation of astrocytes in the plasma treated scaffolds was confirmed by the fact of upregulation of glial fibrillary acidic protein. Above all, oxygenated nanofiber provides an initial culture environment which makes astrocytes activated.

Astrocyte behavior and GFAP expression on Spirulina extract-incorporated PCL nanofiber.

Nanomaterials are attractive for use in biological systems due to their ability to control the microenvironment of cells. Additionally, nanofibers can mimic fibrous characteristics of natural tissues. This study was conducted to assess astrocyte activity and infiltration behavior on Spirulina extract-embedded polycaprolactone (SP-PCL) nanofiber. Astrocytes moved along with the nanofiber, and developed an elongated and stellate shape, which is similar to those in the natural neural tissue. In addition, the expression of GFAP, a biomarker representing the activation of astrocytes, was gradually up-regulated with the increase of the concentration of Spirulina extract, indicating that Spirulina extract can control astrocyte activation. Overall, the results presented herein indicate that SP-PCL nanofiber could be used in astrocyte tissue engineering for neuronal regeneration.

Effect of topography of an electrospun nanofiber on modulation of activity of primary rat astrocytes.

Several biomaterials for neural tissue engineering have recently been proposed for regeneration of damaged tissue and promotion of axonal guidance following CNS injury. When implanted into damaged nerve tissue, biomaterials should favorably induce cell infiltration and axonal guiding while suppressing inflammation. Nanofiber scaffolds are regarded as adequate materials to meet the above requirements; however, most studies of these materials conducted to date have targeted neuronal cells, not glial cells, despite their important function in the injured CNS. In this study, an electrospun nanofibrous scaffold of polycaprolactone (PCL) was investigated with respect to its topographic effects on astrocyte behavior and expression of GFAP. The results revealed that the PCL nanofiber topograghy promoted adhesion, but GFAP expression was down-regulated, leading to reduced astrocytes activity. Taken together, these results indicate that the topographic structure of electrospun nanofibers provides a scaffold that is favorable to neural regeneration via alleviation of astrogliosis.