Nanotesla Institute Ljubljana

Stegne, Slovenia

Nanotesla Institute Ljubljana

Stegne, Slovenia

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Drmota A.,Nanotesla Institute Ljubljana | Drofenik M.,CO NAMASTE | Znidarsic A.,Nanotesla Institute Ljubljana | Znidarsic A.,CO NAMASTE
Ceramics International | Year: 2012

Nano-crystalline strontium hexaferrite (SrFe 12O 19) powder was synthesized using the classical co-precipitation and microemulsion methods. The precursors were obtained by precipitating Sr 2+ and Fe 2+ ions using tetramethylammonium hydroxide and calcinating at different temperatures ranging from 400 °C to 1000 °C in air. The influence of the Sr 2+/Fe 3+ mol ratio and the calcination temperature on the product formation and magnetic properties were studied. The formation of nanosized particles of SrFe 12O 19 with a relatively high saturation magnetization M s = 64 Am 2/kg, remanent magnetization of M r = 39 Am 2/kg and a coercitivity of H c = 5.5 kOe was achieved at a Sr 2+/ Fe 3+ mol ratio of 1:8 calcined at 900 °C. The formation of the SrFe 12O 19 was inspected using XRD analysis, thermogravimetric analysis (TGA), differential thermal analysis (DTA), TEM, and magnetic measurements. © 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


Drmota A.,Nanotesla Institute Ljubljana | Koselj J.,Nanotesla Institute Ljubljana | Drofenik M.,CO NAMASTE | Znidarsic A.,Nanotesla Institute Ljubljana | Znidarsic A.,CO NAMASTE
Journal of Magnetism and Magnetic Materials | Year: 2012

We have investigated composites designed for microwave absorption based on magnetic filler, composed of phases within the SrOFe 2O 3 system, embedded in a polyphenylene sulfide matrix with a concentration ratio of 80:20 by weight. The formation of the nanosized particles of SrFe 12O 19 and Fe 3O 4, as the principal magnetic phases was achieved via the co-precipitation of Sr 2/Fe 3 ions using different molar ratios. The various precursors obtained were calcined between 600 °C and 900 °C in air. The electromagnetic parameters of the composites were measured with a vector network analyzer at 400 MHz to 32 GHz. The results show that with a composite composed of a complex magnetic filler comprising the nanoparticles of two magnetically diverse phases, i.e., a spinel phase as the electromagnetic wave absorber in the lower GHz range and a hexagonal phase operating at a higher GHz range, above 32 GHz, a microwave absorber with an broad absorption range can be prepared. © 2011 Elsevier B.V. All rights reserved.


Drmota A.,Nanotesla Institute Ljubljana | Znidarsic A.,Nanotesla Institute Ljubljana
Informacije MIDEM | Year: 2011

Magnetic (γ-Fe 2O 3) nanoparticles coated with silica (SiO 2) and a narrow particle size distribution were prepared in microemulsion system: water/(SDS+1-butanol)/cyclohexane. The influence of the concentration of reactants in aqueous phase, the temperature of reaction, the pH value during the precipitation of hydroxides and the type of surfactant, on the nature of γ-Fe 2O 3 nanoparticles were investigated. The thickness of SiO 2 shell was carefully controlled by the amount of tetraethoxysilane (TEOS) added to the microemulsion after the precipitation step. Prepared uncoated and coated γ-Fe 2O 3 nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffractometry (XRD) and specific surface area measurements (BET). The specific magnetization (DSM-10, magneto-susceptometer) of the prepared samples was also measured. The specific magnetization of the γ-Fe 2O 3 nanoparticles depended on their size, ranging from 14 to 49 Am 2/kg. The specific magnetization of coated γ-Fe 2O 3 nanoparticles sharply decreased due to the non-magnetic nature of SiO 2 layer.


Koselj J.,Nanotesla Institute Ljubljana | Bregar V.B.,Nanotesla Institute Ljubljana
Informacije MIDEM | Year: 2012

The flanged open-ended coaxial probe is studied using a full-wave model. Influence of parameters like a gap, sample thickness, set-up measurement geometry, probe impedance, size of the flange and size of the sample are investigated and presented. Study is limited to dielectric materials with different characteristics (low loss, high loss). The results showed that error in an air gap is the most important parameter that affects the permittivity measurement accuracy, but also several other parameters are important and present considerable constraints regarding application of open-ended coaxial probe. We also identified the optimal measurement geometry in order to minimize the effect of these parameters.


Prosen L.,Nanotesla Institute Ljubljana | Markelc B.,Institute of Oncology Ljubljana | Dolinsek T.,Institute of Oncology Ljubljana | Music B.,Nanotesla Institute Ljubljana | And 3 more authors.
Molecular Therapy - Nucleic Acids | Year: 2014

The melanoma cell adhesion molecule (MCAM) is involved in melanoma development and its progression, including invasiveness, metastatic potential and angiogenesis. Therefore, MCAM represents a potential target for gene therapy of melanoma, whose expression could be hindered with posttranscriptional specific gene silencing with RNA interference technology. In this study, we constructed a plasmid DNA encoding short hairpin RNA against MCAM (pMCAM) to explore the antitumor and antiangiogenic effects. The experiments were performed in vitro on murine melanoma and endothelial cells, as well as in vivo on melanoma tumors in mice. The antiproliferative, antimigratory, antiangiogenic and antitumor effects were examined after gene therapy with pMCAM. Gene delivery was performed by magnetofection, and its efficacy compared to gene electrotransfer. Gene therapy with pMCAM has proved to be an effective approach in reducing the proliferation and migration of melanoma cells, as well as having antiangiogenic effect in endothelial cells and antitumor effect on melanoma tumors. Magnetofection as a developing nonviral gene delivery system was effective in the transfection of melanoma cells and tumors with pMCAM, but less efficient than gene electrotransfer in in vivo tumor gene therapy due to the lack of antiangiogenic effect after silencing Mcam by magnetofection. © 2014 The American Society of Gene & Cell Therapy All rights reserved.


Prosen L.,Nanotesla Institute Ljubljana | Prijic S.,Institute of Oncology Ljubljana | Music B.,Nanotesla Institute Ljubljana | Lavrencak J.,Institute of Oncology Ljubljana | And 3 more authors.
BioMed Research International | Year: 2013

Magnetofection is a nanoparticle-mediated approach for transfection of cells, tissues, and tumors. Specific interest is in using superparamagnetic iron oxide nanoparticles (SPIONs) as delivery system of therapeutic genes. Magnetofection has already been described in some proof-of-principle studies; however, fine tuning of the synthesis of SPIONs is necessary for its broader application. Physicochemical properties of SPIONs, synthesized by the co-precipitation in an alkaline aqueous medium, were tested after varying different parameters of the synthesis procedure. The storage time of iron(II) sulfate salt, the type of purified water, and the synthesis temperature did not affect physicochemical properties of SPIONs. Also, varying the parameters of the synthesis procedure did not influence magnetofection efficacy. However, for the pronounced gene expression encoded by plasmid DNA it was crucial to functionalize poly(acrylic) acid-stabilized SPIONs (SPIONs-PAA) with polyethyleneimine (PEI) without the adjustment of its elementary alkaline pH water solution to the physiological pH. In conclusion, the co-precipitation of iron(II) and iron(III) sulfate salts with subsequent PAA stabilization, PEI functionalization, and plasmid DNA binding is a robust method resulting in a reproducible and efficient magnetofection. To achieve high gene expression is important, however, the pH of PEI water solution for SPIONs-PAA functionalization, which should be in the alkaline range. © 2013 Lara Prosen et al.


Dolinsek T.,Institute of Oncology Ljubljana | Markelc B.,Institute of Oncology Ljubljana | Bosnjak M.,Institute of Oncology Ljubljana | Blagus T.,Institute of Oncology Ljubljana | And 7 more authors.
Current Gene Therapy | Year: 2015

New targets and therapeutic approaches for vascular targeted strategies in oncology are continuously explored. Endoglin, a co-receptor of TGF-β, is a known target, however, its silencing with vector-based RNA interference technology has not been evaluated yet. Therefore, in our study, we assembled plasmid DNA coding for shRNA against endoglin, and used gene electrotransfer as a delivery method to determine its antitumor and vascular targeted effects. In vitro and in vivo data provide evidence of vascular targeted effects of endoglin silencing. The vascular targeted action of endoglin silencing could be described as a result of two separated effect; antiangiogenic and vascular disrupting effect. This was first supported by in vitro data; predominantly by reduction of proliferation and tube formation of endothelial cells. In the TS/A murine mammary carcinoma model, in which the tumor cells do not express endoglin, reduced tumor growth and number of vessels were observed. Quick destruction of existing activated blood vessels at the site of tumor cells’ injection and sustained growth of tumors afterwards was observed in tumors that were growing in dorsal window chamber by intravital microscopy. This observation supports both vascular disrupting and antiangiogenic action. In conclusion, the results of our study provide evidence of endoglin as a valid target for cancer therapy and support further development of plasmid shRNA delivery, which have prolonged antitumor effect, especially in combined schedules. © 2015 Bentham Science Publishers.


Koselj J.,Nanotesla Institute Ljubljana | Bregar V.B.,Kolektor Magma
Proceedings - 2011 International Conference on Electromagnetics in Advanced Applications, ICEAA'11 | Year: 2011

This paper presents influence of parameters of an open-ended coaxial probe measurement system on magnetic materials. A detailed analysis is done for magnetic fluids and solid magnetic materials. Analysis is done by full-wave model of an open-ended coaxial probe measurement system. Parameters which have influence on measured permittivity and permeability are presented and discussed. © 2011 IEEE.


PubMed | Institute of Oncology Ljubljana, University of Primorska and Nanotesla Institute Ljubljana
Type: | Journal: Molecular therapy. Nucleic acids | Year: 2014

The melanoma cell adhesion molecule (MCAM) is involved in melanoma development and its progression, including invasiveness, metastatic potential and angiogenesis. Therefore, MCAM represents a potential target for gene therapy of melanoma, whose expression could be hindered with posttranscriptional specific gene silencing with RNA interference technology. In this study, we constructed a plasmid DNA encoding short hairpin RNA against MCAM (pMCAM) to explore the antitumor and antiangiogenic effects. The experiments were performed in vitro on murine melanoma and endothelial cells, as well as in vivo on melanoma tumors in mice. The antiproliferative, antimigratory, antiangiogenic and antitumor effects were examined after gene therapy with pMCAM. Gene delivery was performed by magnetofection, and its efficacy compared to gene electrotransfer. Gene therapy with pMCAM has proved to be an effective approach in reducing the proliferation and migration of melanoma cells, as well as having antiangiogenic effect in endothelial cells and antitumor effect on melanoma tumors. Magnetofection as a developing nonviral gene delivery system was effective in the transfection of melanoma cells and tumors with pMCAM, but less efficient than gene electrotransfer in in vivo tumor gene therapy due to the lack of antiangiogenic effect after silencing Mcam by magnetofection.

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