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Recovery study of gold nanoparticle markers from lateral flow immunoassays
Tilen Švarc, Peter Majerič, Darja Feizpour, Žiga Jelen, Matej Zadravec, Timi Gomboc, Rebeka Rudolf, 2023, izvirni znanstveni članek

Opis: Lateral flow immunoassays (LFIAs) are a simple diagnostic device used to detect targeted analytes. Wasted and unused rapid antigen lateral flow immunoassays represent mass waste that needs to be broken down and recycled into new material components. The aim of this study was to recover gold nanoparticles that are used as markers in lateral flow immunoassays. For this purpose, a dissolution process with aqua regia was utilised, where gold nanoparticles were released from the lateral flow immunoassay conjugate pads. The obtained solution was then concentrated further with gold chloride salt (HAuCl4) so that it could be used for the synthesis of new gold nanoparticles in the process of ultrasonic spray pyrolysis (USP). Various characterisation methods including scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy and optical emission spectrometry with inductively coupled plasma were used during this study. The results of this study showed that the recovery of gold nanoparticles from lateral flow immunoassays is possible, and the newly synthesised gold nanoparticles represent the possibility for incorporation into new products.
Ključne besede: gold nanoparticles, recovery, LFIA, ultrasonic spray pyrolysis, characterisation
Objavljeno v DKUM: 09.02.2024; Ogledov: 147; Prenosov: 14
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3.
Polyvinylpyrrolidone-stabilised gold nanoparticle coatings inhibit blood protein adsorption
Hanuma Reddy Tiyyagura, Matej Bračič, Rebeka Rudolf, 2024, izvirni znanstveni članek

Opis: In this work, the ability of polyvinylpyrrolidone (PVP)-stabilised gold nanoparticle (AuNP) coatings to inhibit blood protein adsorption was evaluated by studying timeresolved solid–liquid interactions of the coatings with the model blood protein bovine serum albumin (BSA). Inhibiting unspecific blood protein adsorption is of crucial importance for blood-contacting implant devices, e.g. vascular grafts, stents, artificial joints, and others, as a preventive strategy for bacterial biofilm formation. A quartz crystal microbalance was used in this work to coat the AuNPs on piezoelectric sensors and to follow time-resolved solid–liquid interactions with the proteins. The AuNP coatings were evaluated for their wettability by contact angle measurements, their surface morphology by lightand atomic force microscopy, and their chemical composition by energy-dispersive X-ray spectroscopy. Results revealed a homogeneous distribution of AuNPs on the sensor surface with a dry mass coverage of 3.37 ± 1.46 µg/cm2 and a contact angle of 25.2 ± 1.1°. Solid–liquid interaction studies by quartz crystal microbalance showed a high repellence of BSA from the PVP-stabilised AuNP coatings and the importance of the PVP in the mechanism of repellence. Furthermore, the conformation of the polymer on the coatings as well as its viscoelastic properties were revealed. Finally, the activated partial thrombin time test and fibrinogen adsorption studies revealed that the AuNPs do not accelerate blood coagulation and can partially inhibit the adhesion of fibrinogen, which is a crucial factor in the common blood coagulation cascade. Such AuNPs have the potential to be used in blood-contact medical applications.
Ključne besede: gold nanoparticles, ultrasonic spray pyrolysis, haemocompatibility, protein adsorption, quartz crystal microbalance
Objavljeno v DKUM: 30.01.2024; Ogledov: 179; Prenosov: 11
.pdf Celotno besedilo (4,61 MB)
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4.
Melting point of dried gold nanoparticles prepared with ultrasonic spray pyrolysis and lyophilisation
Žiga Jelen, Marcin Krajewski, Franc Zupanič, Peter Majerič, Tilen Švarc, Ivan Anžel, Jernej Ekar, Sz-Chian Liou, Jerzy Kubacki, Mateusz Tokarczyk, Rebeka Rudolf, 2023, izvirni znanstveni članek

Opis: A coupled process of ultrasonic spray pyrolysis and lyophilisation was used for the synthesis of dried gold nanoparticles. Two methods were applied for determining their melting temperature: uniaxial microcompression and differential scanning calorimetry (DSC) analysis. Uniaxial microcompression resulted in sintering of the dried gold nanoparticles at room temperature with an activation energy of 26–32.5 J/g, which made it impossible to evaluate their melting point. Using DSC, the melting point of the dried gold nanoparticles was measured to be around 1064.3°C, which is close to pure gold. The reason for the absence of a melting point depression in dried gold nanoparticles was their exothermic sintering between 712 and 908.1°C.
Ključne besede: gold nanoparticles, melting point, ultrasonic spray pyrolysis, characterisation
Objavljeno v DKUM: 08.12.2023; Ogledov: 236; Prenosov: 20
.pdf Celotno besedilo (2,83 MB)
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5.
Study of gold nanoparticles conjugated with SARS-CoV-2 S1 spike protein fragments
Žiga Jelen, Janez Kovač, Rebeka Rudolf, 2023, izvirni znanstveni članek

Opis: This study reports on the successful conjugation of SARS-CoV-2 S1 spike protein fragments with gold nanoparticles (AuNPs) that were synthesised with Ultrasonic Spray Pyrolysis (USP). This method enables the continuous synthesis of AuNPs with a high degree of purity, round shapes, and the formation of a surface that allows various modifications. The conjugation mechanism of USP synthesized AuNPs with SARS-CoV-2 S1 spike protein fragments was investigated. A gel electrophoresis experiment confirmed the successful conjugation of AuNPs with SARS-CoV-2 S1 fragments indirectly. X-ray Photoelectron Spectroscopy (XPS) analysis confirmed the presence of characteristic O1s and N1s peaks, which indicated that specific binding between AuNPs and SARS-CoV-2 S1 spike protein fragments takes place via a peptide bond formed with the citrate stabiliser. This bond is coordinated to the AuNP’s surface and the N-terminals of the protein, with the conjugate displaying the expected response within a prototype LFIA test. This study will help in better understanding the behaviour of AuNPs synthesised with USP and their potential use as sensors in colorimetric or electrochemical sensors and LFIA tests.
Ključne besede: gold nanoparticles, ultrasonic spray pyrolysis, conjugation, SARS-CoV-2 S1, characterisation
Objavljeno v DKUM: 07.12.2023; Ogledov: 223; Prenosov: 17
.pdf Celotno besedilo (3,41 MB)
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6.
Physicochemical properties of gold nanoparticles for skin care creams
Peter Majerič, Zorana Jović, Tilen Švarc, Žiga Jelen, Andrej Horvat, Djuro Koruga, Rebeka Rudolf, 2023, izvirni znanstveni članek

Opis: Gold nanoparticles (AuNPs) have now been used in skin care creams for several years, with marketed anti-aging, moisturizing, and regenerative properties. Information on the harmful effects of these nanoparticles is lacking, a concern for the use of AuNPs as cosmetic ingredients. Testing AuNPs without the medium of a cosmetic product is a typical method for obtaining this information, which is mainly dependent on their size, shape, surface charge, and dose. As these properties depend on the surrounding medium, nanoparticles should be characterized in a skin cream without extraction from the cream’s complex medium as it may alter their physicochemical properties. The current study compares the sizes, morphology, and surface changes of produced dried AuNPs with a polyvinylpyrrolidone (PVP) stabilizer and AuNPs embedded in a cosmetic cream using a variety of characterization techniques (TEM, SEM, DLS, zeta potential, BET, UV–vis). The results show no observable differences in their shapes and sizes (spherical and irregular, average size of 28 nm) while their surface charges changed in the cream, indicating no major modification of their primary sizes, morphology, and the corresponding functional properties. They were present as individually dispersed nanoparticles and as groups or clusters of physically separated primary nanoparticles in both dry form and cream medium, showing suitable stability. Examination of AuNPs in a cosmetic cream is challenging due to the required conditions of various characterization techniques but necessary for obtaining a clear understanding of the AuNPs’ properties in cosmetic products as the surrounding medium is a critical factor for determining their beneficial or harmful effects in cosmetic products.
Ključne besede: gold nanoparticles, ultrasonic spray pyrolysis, freeze drying, characterization, creams
Objavljeno v DKUM: 19.04.2023; Ogledov: 550; Prenosov: 53
.pdf Celotno besedilo (5,34 MB)
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7.
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 v DKUM: 19.06.2017; Ogledov: 1359; Prenosov: 391
.pdf Celotno besedilo (5,60 MB)
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8.
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 v DKUM: 14.06.2017; Ogledov: 1434; Prenosov: 394
.pdf Celotno besedilo (5,41 MB)
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9.
Synthesis of Au nanoparticles prepared with ultrasonic spray pyrolysis and hydrogen reduction
Srečko Stopić, Rebeka Rudolf, Jelena Bogovic, Peter Majerič, Miodrag Čolić, Sergej Tomić, Monika Jenko, Bernd Friedrich, 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 v DKUM: 21.12.2015; Ogledov: 1676; Prenosov: 102
.pdf Celotno besedilo (3,17 MB)
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