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Gold in the past, today and future
Rebeka Rudolf, Maša Anžel, Evgenija Marković, Miodrag Čolić, Dragoslav Stamenković, 2012, pregledni znanstveni članek

Opis: This paper deals with gold, which is described as a chemical element. Special attention is paid to its physical-chemical properties and, furthermore, where or in what form it can be found in nature. We discuss the role it has played through history and we inform how gold has been developed to the level it has reached today's value. Still more, when gold is broken into nanoparticles, this form could be highly useful for a wide range of processes, including general nanotechnology, electronics manufacturing and the synthesizing of different functional materials. It is important that we know that gold is also used in industry in many engineering applications (contacts in micro-electronics) and medicine (dental alloys, implants).
Ključne besede: gold, physical-chemical properties, nano-particles, applications
Objavljeno: 01.06.2012; Ogledov: 836; Prenosov: 45
.pdf Celotno besedilo (144,60 KB)

Response of monocyte-derived dendritic cells to rapidly solidified nickel-titanium ribbons with shape memory properties
Sergej Tomić, Rebeka Rudolf, Mihael Brunčko, Ivan Anžel, V. Savić, Miodrag Čolić, 2012, izvirni znanstveni članek

Opis: Ni-Ti Shape Memory Alloys (SMAs) have attracted considerable attention as biomaterials for medical devices. However, the biocompatibility of Ni-Ti SMAs is often unsatisfactory due to their poor surface structure. Here we prepared Rapidly Solidified (RS) Ni-Ti SMA ribbons by melt-spinning and their surface was characterised by Augerelectron spectroscopy, X-ray photoelectron spectrometry and scanning electron microscopy. The biocompatibility of the produced ribbons and their immunomodulatory properties were studied on human monocyte-derived dendritic cells (MoDCs). We showed that melt-spinning of Ni-Ti SMAs can form a thin homogenous oxide layer, which improves their corrosion resistance and subsequent toxicity to MoDCs. Ni-Ti RS ribbons stimulated the maturation of MoDCs, as detected by changes in the cells' morphology and increased expression of HLA-DR, CD86, CD40 and CD83 molecules. However, Ni-Ti RS ribbons enhanced the tolerogenic properties of immature MoDCs, which produced higher levels of IL-10 and IL-27, driving the differentiation of IL-10- and TGF-β-producing CD4+T cells. On the other hand, in the presence of lipopolysaccharide, an important pro-inflammatory biomolecule, Ni-Ti RS ribbons enhanced the allostimulatory and Th1 polarising capacity of MoDCs, whereas the production of Th2 and Th17 cytokines was down-regulated. In conclusion, Ni-Ti RS ribbons possess substantial immunomodulatory properties on MoDCs. These findings might be clinically relevant, because implanted Ni-Ti SMA devices can induce both desired and adverse effects on the immune system, depending on the microenvironmental stimuli.
Ključne besede: nickel-titanium alloy, biocompatibility, cytokines, immunomodulation, monocyte-derived dendritic cells
Objavljeno: 01.06.2012; Ogledov: 726; Prenosov: 15
.pdf Celotno besedilo (1,35 MB)

Synthesis of Au nanoparticles prepared with ultrasonic spray pyrolysis and hydrogen reduction
Srečko Stopić, Bernd Friedrich, Sergej Tomić, Miodrag Čolić, Monika Jenko, Rebeka Rudolf, Peter Majerič, Jelena Bogovic, 2013, izvirni znanstveni članek

Opis: Golden nanoparticles of different sizes and shapes (spherical, cylindrical, triangular and round) where prepared during a synthesis of gold with ultrasonic spray pyrolysis (USP) and hydrogen reduction. The experimental investigations of the (USP) method were performed with an ultrasonic source of 0.8 MHz and 2.5 MHz, acting on the water solution of HAuCl4 forming aerosols with micron-sized and nanosized droplets. The results of the investigation show that the final shape and size of the Au particles depend on the characteristics of the solution and the frequency of the ultrasound. The second step of synthesizing the Au nanoparticles includes the subsequent thermal decomposition of the aerosol droplets in a hydrogen atmosphere between 260°C and 500°C. The investigations showed that the Au nanoparticles prepared in this way are smaller and more homogeneous.
Ključne besede: gold, ultrasonic spray pyrolysis, reduction, nanoparticles
Objavljeno: 21.12.2015; Ogledov: 607; Prenosov: 18
.pdf Celotno besedilo (3,17 MB)

Morphology, aggregation properties, cytocompatibility and anti-inflammatory potential of citrate-stabilized AuNPs prepared by modular Ultrasonic Spray Pyrolysis
Rebeka Rudolf, Peter Majerič, Sergej Tomić, Mohammed Shariq, Urban Ferčec, Bojan Budič, Bernd Friedrich, Dragana Vučević, Miodrag Čolić, 2017, izvirni znanstveni članek

Opis: Ultrasonic Spray Pyrolysis (USP) possesses a great potential for production of higher quantities of gold nanoparticles (AuNPs), thus overcoming the problem of batch-to-batch variations in their properties. Recently, we demonstrated that USP with an additional evaporation chamber (modular USP) led to a better size control of AuNPs. However, their morphology, stability, toxicity, and immunomodulatory properties have not been investigated completely. Here, two types of spherical AuNPs were produced by using different USP parameters, followed by their stabilization in Na-citrate solution. No significant changes in their size, agglomeration, and -potential occurred 3 months after their initial production in citrate solution. However, the conditioning of AuNPs in serum-containing cell culture media for 24 h induced an increase in the AuNPs’ hydrodynamic size and a red shift in their Surface Plasmon Resonance, pointing to their instability in biological media. Cytocompatibility tests showed that the produced AuNPs were internalized by L929 cells and primary human monocytes and were not cytotoxic at the concentrations lower than 200 μg/mL, but they exhibited antiproliferative and anti-inflammatory effects, respectively. AuNPs reduced the percentage of CD14+CD16+ but not CD14lowCD16+ monocytes in vitro and reduced the expression of CD86, HLA-DR, TNF-α, and IL-12/IL-23 by these cells. These results indicate that the anti-inflammatory effects of citrate-capped AuNPs produced by modular USP could be beneficial for their application in the treatment of inflammatory conditions.
Ključne besede: Ultrasonic Spray Pyrolysis, gold nanoparticles, plasmon resonance, monocytes, antiinflammatory effects
Objavljeno: 14.06.2017; Ogledov: 236; Prenosov: 33
.pdf Celotno besedilo (5,41 MB)

Size-dependent effects of gold nanoparticles uptake on maturation and antitumor functions of human dendritic cells in vitro
Sergej Tomić, Nina Ogrinc Potočnik, Rebeka Rudolf, Primož Pelicon, Ivan Anžel, Marjan Rupnik, Jelena Đokić, Saša Vasilijić, Dragana Vučević, Petar Milosavljević, Srđa Janković, Jelena Rajković, Bernd Friedrich, Miodrag Čolić, 2014, izvirni znanstveni članek

Opis: Gold nanoparticles (GNPs) are claimed as outstanding biomedical tools for cancer diagnostics and photo-thermal therapy, but without enough evidence on their potentially adverse immunological effects. Using a model of human dendritic cells (DCs), we showed that 10 nm- and 50 nm-sized GNPs (GNP10 and GNP50, respectively) were internalized predominantly via dynamin-dependent mechanisms, and they both impaired LPS-induced maturation and allostimulatory capacity of DCs, although the effect of GNP10 was more prominent. However, GNP10 inhibited LPS-induced production of IL-12p70 by DCs, and potentiated their Th2 polarization capacity, while GNP50 promoted Th17 polarization. Such effects of GNP10 correlated with a stronger inhibition of LPS-induced changes in Ca2+ oscillations, their higher number per DC, and more frequent extraendosomal localization, as judged by live-cell imaging, proton, and electron microscopy, respectively. Even when released from heat-killed necrotic HEp-2 cells, GNP10 inhibited the necrotic tumor cell-induced maturation and functions of DCs, potentiated their Th2/Th17 polarization capacity, and thus, impaired the DCs% capacity to induce T cell-mediated anti-tumor cytotoxicity in vitro. Therefore, GNP10 could potentially induce more adverse DC-mediated immunological effects, compared to GNP50.
Ključne besede: gold, nanoparticles, antitumor function
Objavljeno: 19.06.2017; Ogledov: 245; Prenosov: 33
.pdf Celotno besedilo (5,60 MB)

Native cellulose nanofibrills induce immune tolerance in vitro by acting on dendritic cells
Sergej Tomić, Vanja Kokol, Dušan Mihajlović, Aleksandar Mirčić, Miodrag Čolić, 2016, izvirni znanstveni članek

Opis: Cellulose nanofibrills (CNFs) are attractive biocompatible, natural nanomaterials for wide biomedical applications. However, the immunological mechanisms of CNFs have been poorly investigated. Considering that dendritic cells (DCs) are the key immune regulatory cells in response to nanomaterials, our aim was to investigate the immunological mechanisms of CNFs in a model of DC-mediated immune response. We found that non-toxic concentrations of CNFs impaired the differentiation, and subsequent maturation of human monocyte-derived (mo)-DCs. In a co-culture with CD4+T cells, CNF-treated mo-DCs possessed a weaker allostimulatory and T helper (Th)1 and Th17 polarizing capacity, but a stronger capacity to induce Th2 cells and CD4+CD25hiFoxP3hi regulatory T cells. This correlated with an increased immunoglobulin-like transcript-4 and indolamine dioxygenase-1 expression by CNF-treated mo-DCs, following the partial internalization of CNFs and the accumulation of CD209 and actin bundles at the place of contacts with CNFs. Cumulatively, we showed that CNFs are able to induce an active immune tolerance by inducing tolerogenic DCs, which could be beneficial for the application of CNFs in wound healing and chronic inflammation therapies.
Ključne besede: nanocellulose, cytotoxicity, T-cell proliferation, cytokine production, in vitro
Objavljeno: 23.06.2017; Ogledov: 224; Prenosov: 21
.pdf Celotno besedilo (2,87 MB)

Rhodium platings
Rebeka Rudolf, Bojan Budić, Dragoslav Stamenković, Miodrag Čolić, Andrej Ivanič, Borut Kosec, 2013, kratki znanstveni prispevek

Opis: Modern rhodium plating solutions are based on either sulphate or phosphate. Although in theory there are four possible combinations, in practice only three different rhodium electrolytes are used. These are based on dilutions of rhodium sulphate or phosphate concentrates with added sulphuric or phosphoric acid. These processes are be discussed in this paper with a demonstration of Rh platings in the Slovenian firm Zlatarna Celje d.d.
Ključne besede: rhodium, plating, jewellery, properties
Objavljeno: 03.07.2017; Ogledov: 248; Prenosov: 36
.pdf Celotno besedilo (750,35 KB)

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