| 1. |
- Andõn, F. T., et al.
(författare)
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Biodegradation of Single-Walled Carbon Nanotubes by Eosinophil Peroxidase
- 2013
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Ingår i: Small. - : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 9:16, s. 2721-2729
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Bhattacharya, Kunal, et al.
(författare)
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Enzymatic 'stripping' and degradation of PEGylated carbon nanotubes
- 2014
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 6:24, s. 14686-14690
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Tidskriftsartikel (refereegranskat)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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| 3. |
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| 4. |
- Bogren, Sara, et al.
(författare)
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Classification of Magnetic Nanoparticle Systems—Synthesis, Standardization and Analysis Methods in the NanoMag Project
- 2015
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 16:9, s. 20308-20325
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Tidskriftsartikel (refereegranskat)abstract
- This study presents classification of different magnetic single- and multi-core particle systems using their measured dynamic magnetic properties together with their nanocrystal and particle sizes. The dynamic magnetic properties are measured with AC (dynamical) susceptometry and magnetorelaxometry and the size parameters are determined from electron microscopy and dynamic light scattering. Using these methods, we also show that the nanocrystal size and particle morphology determines the dynamic magnetic properties for both single- and multi-core particles. The presented results are obtained from the four year EU NMP FP7 project, NanoMag, which is focused on standardization of analysis methods for magnetic nanoparticles.
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| 5. |
- Booth, Andy, et al.
(författare)
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Freshwater dispersion stability of PAA-stabilised cerium oxide nanoparticles and toxicity towards Pseudokirchneriella subcapitata
- 2015
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 505, s. 596-605
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Tidskriftsartikel (refereegranskat)abstract
- An aqueous dispersion of poly (acrylic acid)-stabilised cerium oxide (CeO2) nanoparticles (PAA-CeO2) was evaluated for its stability in a range of freshwater ecotoxicity media (MHRW, TG 201 and M7), with and without natural organic matter (NOM). In a 15day dispersion stability study, PAA-CeO2 did not undergo significant aggregation in any media type. Zeta potential varied between media types and was influenced by PAA-CeO2 concentration, but remained constant over 15days. NOM had no influence on PAA-CeO2 aggregation or zeta potential. The ecotoxicity of the PAA-CeO2 dispersion was investigated in 72h algal growth inhibition tests using the freshwater microalgae Pseudokirchneriella subcapitata. PAA-CeO2 EC50 values for growth inhibition (GI; 0.024mg/L) were 2-3 orders of magnitude lower than pristine CeO2 EC50 values reported in the literature. The concentration of dissolved cerium (Ce3+/Ce4+) in PAA-CeO2 exposure suspensions was very low, ranging between 0.5 and 5.6μg/L. Free PAA concentration in the exposure solutions (0.0096-0.0384mg/L) was significantly lower than the EC10 growth inhibition (47.7mg/L) value of pure PAA, indicating that free PAA did not contribute to the observed toxicity. Elemental analysis indicated that up to 38% of the total Cerium becomes directly associated with the algal cells during the 72h exposure. TOF-SIMS analysis of algal cell wall compounds indicated three different modes of action, including a significant oxidative stress response to PAA-CeO2 exposure. In contrast to pristine CeO2 nanoparticles, which rapidly aggregate in standard ecotoxicity media, PAA-stabilised CeO2 nanoparticles remain dispersed and available to water column species. Interaction of PAA with cell wall components, which could be responsible for the observed biomarker alterations, could not be excluded. This study indicates that the increased dispersion stability of PAA-CeO2 leads to an increase in toxicity compared to pristine non-stabilised forms.
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| 6. |
- Fadeel, Bengt, et al.
(författare)
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Keeping it real : The importance of material characterization in nanotoxicology
- 2015
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 468:3, s. 498-503
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Forskningsöversikt (refereegranskat)abstract
- Nanomaterials are small and the small size and corresponding large surface area of nanomaterials confers specific properties, making these materials desirable for various applications, not least in medicine. However, it is pertinent to ask whether size is the only property that matters for the desirable or detrimental effects of nanomaterials? Indeed, it is important to know not only what the material looks like, but also what it is made of, as well as how the material interacts with its biological surroundings. It has been suggested that guidelines should be implemented on the types of information required in terms of physicochemical characterization of nanomaterials for toxicological studies in order to improve the quality and relevance of the published results. This is certainly a key issue, but it is important to keep in mind that material characterization should be fit-for-purpose, that is, the information gathered should be relevant for the end-points being studied.
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| 7. |
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| 8. |
- Fornara, Andrea, 1980-
(författare)
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Magnetic nanostructured materials for advanced bio-applications
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the recent years, nanostructured magnetic materials and their use in biomedical and biotechnological applications have received a lot of attention. In this thesis, we developed tailored magnetic nanoparticles for advanced bio-applications, such as direct detection of antibodies in biological samples and stimuli responsive drug delivery system. For sensitive and selective detection of biomolecules, thermally blocked iron oxide nanoparticles with specific magnetic properties are synthesized by thermal hydrolysis to achieve a narrow size distribution just above the superparamagnetic limit. The prepared nanoparticles were characterized and functionalized with biomolecules for use in a successful biosensor system. We have demonstrated the applicability of this type of nanoparticles for the detection of Brucella antibodies as model compound in serum samples and very low detection limits were achieved (0.05 mg/mL). The second part is concerning an in-depth investigation of the evolution of the thermally blocked magnetic nanoparticles. In this study, the formation of the nanoparticles at different stages during the synthesis was investigated by high resolution electron microscopy and correlated to their magnetic properties. At early stage of the high temperature synthesis, small nuclei of 3.5 nm are formed and the particles size increases successively until they reach a size of 17-20 nm. The small particles first exhibit superparamagnetic behavior at the early stage of synthesis and then transform to thermally blocked behavior as their size increases and passes the superparamagnetic limit. The last section of the Thesis is related to the development of novel drug delivery system based on magnetically controlled release rate. The system consists of hydrogel of Pluronic FP127 incorporating superparamagnetic iron oxide nanoparticles to form a ferrogel. The sol to gel formation of the hydrogel could be tailored to be solid at body temperature and thus have the ability to be injected inside living biological tissues. In order to evaluate the drug loading and release, the hydrophobic drug indomethacin was selected as a model compound. The drug could be loaded in the ferrogel owning to the oil in water micellar structure. We have studied the release rate from the ferrogel in the absence and presence of magnetic field. We have demonstrated that the drug release rate can be significantly enhanced by use of external magnetic field decreasing the half time of the release to more than 50% (from 3200 to 1500 min) upon the application of the external magnetic field. This makes the developed ferrogel a very promising drug delivery system that does not require surgical implant procedure for medical treatment and gives the possibility of enhancing the rate of release by external magnetic field.
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| 9. |
- Fornara, Andrea, 1980-
(författare)
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Multifunctional nanomaterials for diagnostic and therapeutic applications
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the past few years, the use of nanostructured materials in medical applications hasdramatically increased, both in the research phase and for clinical purposes, due to thepeculiar properties and the ability of such materials to interact at a similar scale withbiological entities. In this thesis, we developed tailored magnetic multifunctionalnanoparticles for diagnostic and therapeutic applications, such as detection ofbiomolecules, simultaneous enhanced magnetic resonance imaging (MRI), fluorescentvisualization and controlled drug release.For sensitive and selective detection of specific biomolecules, thermally blocked ironoxide nanoparticles with tailored magnetic properties were developed. The formation ofsuch nanoparticles has been studied both in terms of size and magnetic behavior in liquidsuspension or in polymer matrixes. These particles with narrow size distribution (averagediameter of 19 nm) were surface functionalized by antigen molecules and were used forthe detection of Brucella antibodies in biological samples. The binding of biomoleculesresults in an increase in the particle’s hydrodynamic diameter, affecting the relaxationbehavior that was monitored by magnetic measurements. This sensing system is a fastand sensitive biosensor with very low detection limits (0.05 μg/mL).Superparamagnetic iron oxide nanoparticles (SPION) have been synthesized withaverage diameter of 10-12 nm, narrow size distribution, high crystallinity and superiormagnetic properties as liquid suspensions or embedded in a bulk transparent magneticnanocomposite. These nanoparticles were synthesized in organic solvents and, after phasetransfer with Pluronic F127 amphiphilic copolymer, show excellent relaxivity properties(high r2/r1 ratio) and great contrast enhancement in T2 weighted MRI, confirmed by invivostudies of rat inner ear.SPION have been used as a component for different multifunctional nanostructures. Thefirst system based on poly (L,L lactide)-methoxy polyethylene glycol (PLLA-mPEG)copolymer has been prepared by an emulsion/evaporation process that lead to polymericnanoparticles containing several imaging agents, such as SPION, quantum dots (QDs)and gold nanorods as well as indomethacin (IMC) as therapeutic payload. With a similarprocedure, but using poly (lactide-co-glycolide) (PLGA-PEG-NH2) copolymer, a secondtype of multifunctional nanoparticles has been obtained. Their size can be tailored from70 to 150 nm varying synthesis parameters, such as the surfactant concentration or waterto oil ratio. Both these polymer-based multifunctional nanoparticles can be visualized byfluorescence microscopy (QDs photoemission) and MRI (SPION magnetization) and theycan be used for photothermal therapy (gold nanorods) and drug delivery. The last systemconsists of SPION nanoparticles coated with PLLA directly on the surface by an in-situpolymerization process. A hydrophobic drug was loaded before the phase transfer withPluronic F127 and these nanoparticles show simultaneous MRI T2 contrast enhancementas well as high drug loading and sustained delivery.Controlling the drug release rate is also a critical parameter for tailored therapeutictreatments, and for this reason we developed a novel drug delivery system based on theintegration of SPION and Pluronic F127 gels. IMC was loaded in the ferrogel (with atailored gelation temperature) and its release rate was triggered by applying an externalmagnetic field owing to the SPION magnetic properties.
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| 10. |
- Fornara, Andrea, et al.
(författare)
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PLGA-PEG multifunctional nanoparticles for simultaneous drug delivery and imaging by MRI and fluorescence microscopy
- 2012
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Ingår i: Technical Proceedings of the 2012 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2012. - 9781466562769 ; , s. 4-7
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Konferensbidrag (refereegranskat)abstract
- This work deals with the synthesis of multifunctional nanoparticles based on biocompatible di-block copolymer (PLGA-PEG) via an emulsion-evaporation method. To enable their visualization, these nanoparticles can be loaded with iron oxide nanoparticles for Magnetic Resonance Imaging (MRI) and/or quantum dots for fluorescent microscopy. A therapeutic agent, Indomethacin, can also be loaded and released. The influence of synthesis parameters on nanoparticle size (in the range 70-150 nm) has been controlled to achieve specific cellular interactions avoiding possible immuno-response. These multifunctional nanoparticles possess excellent photoemission properties for fluorescent microscopy and enhanced contrast efficiency for T 2 MRI imaging compared to available agents used today. In-vitro experiments confirm the low cytotoxicity of such nanoparticles and their excellent visualization properties by MRI and fluorescence microscopy in cells and biological tissues.
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