| 2. |
- Pujari-Palmer, Shiuli, et al.
(author)
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In vivo and in vitro evaluation of hydroxyapatite nanoparticle morphology on the acute inflammatory response
- 2016
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In: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 90, s. 1-11
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Journal article (peer-reviewed)abstract
- Biomedical implants have been widely used in bone repair applications. However, nanosized degradation products from these implants could elicit an inflammatory reaction, which may lead to implant failure. It is well known that the size, chemistry, and charge of these nanoparticles can modulate this response, but little is known regarding the role that the particle's morphology plays in inducing inflammation. The present study aims to investigate the effect of hydroxyapatite nanoparticle (HANPs) morphology on inflammation, in-vitro and in-vivo. Four distinct HANP morphologies were fabricated and characterized: long rods, dots, sheets, and fibers. Primary human polymorphonuclear cells (PMNCs), mononuclear cells (MNCs), and human dermal fibroblasts (hDFs) were exposed to HANPs and alterations in cell viability, morphology, apoptotic activity, and reactive oxygen species (ROS) production were evaluated, in vitro. PMNCs and hDFs experienced a 2-fold decrease in viability following exposure to fibers, while MNC viability decreased 5-fold after treatment with the dots. Additionally, the fibers stimulated an elevated ROS response in both PMNCs and MNCs, and the largest apoptotic behavior for all cell types. Furthermore, exposure to fibers and dots resulted in greater capsule thickness when implanted subcutaneously in mice. Collectively, these results suggest that nanoparticle morphology can significantly impact the inflammatory response.
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| 3. |
- Rubino, Stefano, et al.
(author)
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A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes
- 2016
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In: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 22:1, s. 250-256
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Journal article (peer-reviewed)abstract
- We present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I-0(t), as a function of the specimen thickness t (t < < lambda; where lambda is the absorption constant for graphite). We show that in thin graphite crystals the transmitted intensity is a linear function of t. Furthermore, high-resolution (HR) TEM simulations are performed to obtain lambda for a 001 zone axis orientation, in a two-beam case and in a low symmetry orientation. Subsequently, HR (used to determine t) and bright-field (to measure I-0(0) and I-0(t)) images were acquired to experimentally determine lambda. The experimental value measured in low symmetry orientation matches the calculated value (i.e., lambda = 225 +/- 9 nm). The simulations also show that the linear approximation is valid up to a sample thickness of 3-4 nm regardless of the orientation and up to several ten nanometers for a low symmetry orientation. When compared with standard techniques for thickness determination of graphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.
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