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Decreased astroglial cell adhesion and proliferation on zinc oxide nanoparticle polyurethane composites.

Seil JT, Webster TJ - Int J Nanomedicine (2008)

Bottom Line: The surface chemistry was characterized via X-ray photoelectron spectroscopy.Astrocyte adhesion was significantly reduced on ZnO nanoparticle/polyurethane (PU) composites with a weight ratio of 50:50 (PU:ZnO) wt.%, 75:25 (PU:ZnO) wt.%, and 90:10 (PU:ZnO) wt.% in comparison to pure PU.The successful production of ZnO nanoparticle composite scaffolds suitable for decreasing astroglial cell density demonstrates their potential as a nerve guidance channel material with greater efficiency than what may be available today.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Nanomedicine Research, Division of Engineering, Brown University, Providence, RI 02912, USA.

ABSTRACT
Nanomaterials offer a number of properties that are of interest to the field of neural tissue engineering. Specifically, materials that exhibit nanoscale surface dimensions have been shown to promote neuron function while simultaneously minimizing the activity of cells such as astrocytes that inhibit central nervous system regeneration. Studies demonstrating enhanced neural tissue regeneration in electrical fields through the use of conductive materials have led to interest in piezoelectric materials (or those materials which generate a transient electrical potential when mechanically deformed) such as zinc oxide (ZnO). It has been speculated that ZnO nanoparticles possess increased piezoelectric properties over ZnO micron particles. Due to this promise in neural applications, the objective of the present in vitro study was, for the first time, to assess the activity of astroglial cells on ZnO nanoparticle polymer composites. ZnO nanoparticles embedded in polyurethane were analyzed via scanning electron microscopy to evaluate nanoscale surface features of the composites. The surface chemistry was characterized via X-ray photoelectron spectroscopy. Astroglial cell response was evaluated based on cell adhesion and proliferation. Astrocyte adhesion was significantly reduced on ZnO nanoparticle/polyurethane (PU) composites with a weight ratio of 50:50 (PU:ZnO) wt.%, 75:25 (PU:ZnO) wt.%, and 90:10 (PU:ZnO) wt.% in comparison to pure PU. The successful production of ZnO nanoparticle composite scaffolds suitable for decreasing astroglial cell density demonstrates their potential as a nerve guidance channel material with greater efficiency than what may be available today.

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Scanning electron micrographs of the ZnO/PU composites. 50:50 (PU:ZnO) wt.% at 6,000X (a) and 30,000X (b); 75:25 (PU:ZnO) wt.% at 6,000X (c) and 30,000X (d); 90:10 (PU: ZnO) wt.% at 6,000X (e) and 30,000X (f); 98:2 (PU:ZnO) wt.% at 6,000X (g) and 30,000X (h); 100:0 (PU:ZnO) wt.% at 6,000X (i) and 30,000X (j).Notes: Scale bar for images in left column = 5 μm. Scale bar for images in right column = 1 μm.
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f1-ijn-3-523: Scanning electron micrographs of the ZnO/PU composites. 50:50 (PU:ZnO) wt.% at 6,000X (a) and 30,000X (b); 75:25 (PU:ZnO) wt.% at 6,000X (c) and 30,000X (d); 90:10 (PU: ZnO) wt.% at 6,000X (e) and 30,000X (f); 98:2 (PU:ZnO) wt.% at 6,000X (g) and 30,000X (h); 100:0 (PU:ZnO) wt.% at 6,000X (i) and 30,000X (j).Notes: Scale bar for images in left column = 5 μm. Scale bar for images in right column = 1 μm.

Mentions: Sample characterization via SEM (Figure 1) and XPS (Table 1) suggested that the ZnO nanoparticles exposed on the composite surface contributed to larger amounts of nanoroughness. While SEM images revealed nanoscale features of individual ZnO nanoparticles at or near the material surface, XPS analysis confirmed that the particles were in fact at the material surface and were not coated by the polymer. SEM images suggested that as ZnO nanoparticle concentration increased, surface nanofeatures of the sample also increased. At lower concentrations, nanoparticle agglomeration was more evident in SEM images. XPS analysis indicated that as the nanoparticle concentration increased, more zinc was exposed at the material surface. Zinc was detected at the surface of the composites at weight ratios of 50:50 (PU:ZnO) wt.% and 75:25 (PU:ZnO) wt.%. Zinc was not detected at the surface of the composites at weight ratios of 90:10 (PU:ZnO) wt.% or 98:2 (PU:ZnO) wt.%. However, since XPS is unable to confirm the presence of an element at very lower concentrations, this did not confirm the absence of zinc at the surface of these samples. By extrapolating from XPS data which indicated that zinc covered 3.98% of the surface of a sample with a weight ratio of 50:50 (PU:ZnO) wt.% and 2.11% of the surface of a sample with a weight ratio of 75:25 (PU:ZnO) wt.%, it was estimated that the area of zinc coverage for the 90:10 (PU:ZnO) wt.% and 98:2 (PU:ZnO) wt.% composites could be less than 1% of the surface area. With a coverage area this low, the XPS system may not have been able to accurately detect the presence of zinc.


Decreased astroglial cell adhesion and proliferation on zinc oxide nanoparticle polyurethane composites.

Seil JT, Webster TJ - Int J Nanomedicine (2008)

Scanning electron micrographs of the ZnO/PU composites. 50:50 (PU:ZnO) wt.% at 6,000X (a) and 30,000X (b); 75:25 (PU:ZnO) wt.% at 6,000X (c) and 30,000X (d); 90:10 (PU: ZnO) wt.% at 6,000X (e) and 30,000X (f); 98:2 (PU:ZnO) wt.% at 6,000X (g) and 30,000X (h); 100:0 (PU:ZnO) wt.% at 6,000X (i) and 30,000X (j).Notes: Scale bar for images in left column = 5 μm. Scale bar for images in right column = 1 μm.
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f1-ijn-3-523: Scanning electron micrographs of the ZnO/PU composites. 50:50 (PU:ZnO) wt.% at 6,000X (a) and 30,000X (b); 75:25 (PU:ZnO) wt.% at 6,000X (c) and 30,000X (d); 90:10 (PU: ZnO) wt.% at 6,000X (e) and 30,000X (f); 98:2 (PU:ZnO) wt.% at 6,000X (g) and 30,000X (h); 100:0 (PU:ZnO) wt.% at 6,000X (i) and 30,000X (j).Notes: Scale bar for images in left column = 5 μm. Scale bar for images in right column = 1 μm.
Mentions: Sample characterization via SEM (Figure 1) and XPS (Table 1) suggested that the ZnO nanoparticles exposed on the composite surface contributed to larger amounts of nanoroughness. While SEM images revealed nanoscale features of individual ZnO nanoparticles at or near the material surface, XPS analysis confirmed that the particles were in fact at the material surface and were not coated by the polymer. SEM images suggested that as ZnO nanoparticle concentration increased, surface nanofeatures of the sample also increased. At lower concentrations, nanoparticle agglomeration was more evident in SEM images. XPS analysis indicated that as the nanoparticle concentration increased, more zinc was exposed at the material surface. Zinc was detected at the surface of the composites at weight ratios of 50:50 (PU:ZnO) wt.% and 75:25 (PU:ZnO) wt.%. Zinc was not detected at the surface of the composites at weight ratios of 90:10 (PU:ZnO) wt.% or 98:2 (PU:ZnO) wt.%. However, since XPS is unable to confirm the presence of an element at very lower concentrations, this did not confirm the absence of zinc at the surface of these samples. By extrapolating from XPS data which indicated that zinc covered 3.98% of the surface of a sample with a weight ratio of 50:50 (PU:ZnO) wt.% and 2.11% of the surface of a sample with a weight ratio of 75:25 (PU:ZnO) wt.%, it was estimated that the area of zinc coverage for the 90:10 (PU:ZnO) wt.% and 98:2 (PU:ZnO) wt.% composites could be less than 1% of the surface area. With a coverage area this low, the XPS system may not have been able to accurately detect the presence of zinc.

Bottom Line: The surface chemistry was characterized via X-ray photoelectron spectroscopy.Astrocyte adhesion was significantly reduced on ZnO nanoparticle/polyurethane (PU) composites with a weight ratio of 50:50 (PU:ZnO) wt.%, 75:25 (PU:ZnO) wt.%, and 90:10 (PU:ZnO) wt.% in comparison to pure PU.The successful production of ZnO nanoparticle composite scaffolds suitable for decreasing astroglial cell density demonstrates their potential as a nerve guidance channel material with greater efficiency than what may be available today.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Nanomedicine Research, Division of Engineering, Brown University, Providence, RI 02912, USA.

ABSTRACT
Nanomaterials offer a number of properties that are of interest to the field of neural tissue engineering. Specifically, materials that exhibit nanoscale surface dimensions have been shown to promote neuron function while simultaneously minimizing the activity of cells such as astrocytes that inhibit central nervous system regeneration. Studies demonstrating enhanced neural tissue regeneration in electrical fields through the use of conductive materials have led to interest in piezoelectric materials (or those materials which generate a transient electrical potential when mechanically deformed) such as zinc oxide (ZnO). It has been speculated that ZnO nanoparticles possess increased piezoelectric properties over ZnO micron particles. Due to this promise in neural applications, the objective of the present in vitro study was, for the first time, to assess the activity of astroglial cells on ZnO nanoparticle polymer composites. ZnO nanoparticles embedded in polyurethane were analyzed via scanning electron microscopy to evaluate nanoscale surface features of the composites. The surface chemistry was characterized via X-ray photoelectron spectroscopy. Astroglial cell response was evaluated based on cell adhesion and proliferation. Astrocyte adhesion was significantly reduced on ZnO nanoparticle/polyurethane (PU) composites with a weight ratio of 50:50 (PU:ZnO) wt.%, 75:25 (PU:ZnO) wt.%, and 90:10 (PU:ZnO) wt.% in comparison to pure PU. The successful production of ZnO nanoparticle composite scaffolds suitable for decreasing astroglial cell density demonstrates their potential as a nerve guidance channel material with greater efficiency than what may be available today.

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Related in: MedlinePlus