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- Andõn, F. T., et al.
(author)
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Biodegradation of Single-Walled Carbon Nanotubes by Eosinophil Peroxidase
- 2013
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In: Small. - : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 9:16, s. 2721-2729
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Journal article (peer-reviewed)abstract
- Eosinophil peroxidase (EPO) is one of the major oxidant-producing enzymes during inflammatory states in the human lung. The degradation of single-walled carbon nanotubes (SWCNTs) upon incubation with human EPO and H2O 2 is reported. Biodegradation of SWCNTs is higher in the presence of NaBr, but neither EPO alone nor H2O2 alone caused the degradation of nanotubes. Molecular modeling reveals two binding sites for SWCNTs on EPO, one located at the proximal side (same side as the catalytic site) and the other on the distal side of EPO. The oxidized groups on SWCNTs in both cases are stabilized by electrostatic interactions with positively charged residues. Biodegradation of SWCNTs can also be executed in an ex vivo culture system using primary murine eosinophils stimulated to undergo degranulation. Biodegradation is proven by a range of methods including transmission electron microscopy, UV-visible-NIR spectroscopy, Raman spectroscopy, and confocal Raman imaging. Thus, human EPO (in vitro) and ex vivo activated eosinophils mediate biodegradation of SWCNTs: an observation that is relevant to pulmonary responses to these materials. Human eosinophil peroxidase (EPO) is able to degrade SWCNTs in vitro in the presence of H2O2. EPO is one of the major oxidant-generating enzymes present in human lungs during inflammatory states. The biodegradation of SWCNTs is evidenced also in an ex vivo culture system using primary murine eosinophils stimulated to undergo degranulation. These results are relevant to potential respiratory exposure to carbon nanotubes.
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- Bender, P., et al.
(author)
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Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7
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Journal article (peer-reviewed)abstract
- The structural and magnetic properties of magnetic multi-core particles were determined by numerical inversion of small angle scattering and isothermal magnetisation data. The investigated particles consist of iron oxide nanoparticle cores (9 nm) embedded in poly(styrene) spheres (160 nm). A thorough physical characterisation of the particles included transmission electron microscopy, X-ray diffraction and asymmetrical flow field-flow fractionation. Their structure was ultimately disclosed by an indirect Fourier transform of static light scattering, small angle X-ray scattering and small angle neutron scattering data of the colloidal dispersion. The extracted pair distance distribution functions clearly indicated that the cores were mostly accumulated in the outer surface layers of the poly(styrene) spheres. To investigate the magnetic properties, the isothermal magnetisation curves of the multicore particles (immobilised and dispersed in water) were analysed. The study stands out by applying the same numerical approach to extract the apparent moment distributions of the particles as for the indirect Fourier transform. It could be shown that the main peak of the apparent moment distributions correlated to the expected intrinsic moment distribution of the cores. Additional peaks were observed which signaled deviations of the isothermal magnetisation behavior from the non-interacting case, indicating weak dipolar interactions.
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- Bhattacharya, K., et al.
(author)
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Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant
- 2015
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In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 91, s. 506-517
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Journal article (peer-reviewed)abstract
- Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H2O2 + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV-Vis-NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H2O2 + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant 'bio-corona' and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system.
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- Ludwig, Frank, et al.
(author)
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Magnetic, Structural, and Particle Size Analysis of Single- and Multi-Core Magnetic Nanoparticles
- 2014
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In: IEEE Transactions on Magnetics. - 0018-9464 .- 1941-0069. ; 50:11
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Journal article (peer-reviewed)abstract
- We have measured and analyzed three different commercial magnetic nanoparticle systems, both multi-core and single-core in nature, with the particle (core) size ranging from 20 to 100 nm. Complementary analysis methods and same characterization techniques were carried out in different labs and the results are compared with each other. The presented results primarily focus on determining the particle size-both the hydrodynamic size and the individual magnetic core size-as well as magnetic and structural properties. The used analysis methods include transmission electron microscopy, static and dynamic magnetization measurements, and Mossbauer spectroscopy. We show that particle (hydrodynamic and core) size parameters can be determined from different analysis techniques and the individual analysis results agree reasonably well. However, in order to compare size parameters precisely determined from different methods and models, it is crucial to establish standardized analysis methods and models to extract reliable parameters from the data.
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- Bhattacharya, Kunal, et al.
(author)
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Enzymatic 'stripping' and degradation of PEGylated carbon nanotubes
- 2014
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6:24, s. 14686-14690
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Journal article (peer-reviewed)abstract
- Single-walled carbon nanotubes (SWCNTs) coated or functionalized with PEG chains of different molecular weight were assessed for their propensity to undergo biodegradation under in vitro conditions using recombinant myeloperoxidase (MPO) or ex vivo using freshly isolated primary human neutrophils. Our findings suggest that under natural conditions, a combined process of 'stripping' (i.e., defunctionalization) and biodegradation of PEG-SWCNTs might occur and that PEG-SWCNTs are a promising-and degradable-nanomedicine vector.
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