1. Life cycle assessment (LCA) of the impact on the environment of a cosmetic cream with gold nanoparticles and hydroxylated fullerene ingredientsRebeka Rudolf, Peter Majerič, Zorka Novak-Pintarič, Andrej Horvat, Damjan Krajnc, 2024, original scientific article Abstract: This review provides a comprehensive Life Cycle Assessment (LCA) of a cosmetic cream to assess the environmental impacts throughout its entire life cycle, from raw material extraction to disposal, using the methodology according to international standards. The LCA was performed using the OpenLCA 2.0.1 software, with data from the Ecoinvent 3.8 database and relevant literature. The assessment focused on multiple impact categories, including climate change, acidification, eutrophication (freshwater, marine and terrestrial), ecotoxicity (freshwater), human toxicity (cancer and non-cancer), ionizing radiation, land use, ozone depletion, photochemical ozone formation, resource use (fossils, minerals and metals), and water use. The LCA of a cosmetic cream containing gold nanoparticles revealed significant environmental impacts across critical categories. The total climate change potential was 2596.95 kg CO2 eq., driven primarily by nanoparticle synthesis (60.7%) and electricity use (31.9%). Eutrophication of freshwater had the highest normalized result (3.000), with nanoparticle synthesis contributing heavily, indicating the need for improved wastewater treatment. The resource use (minerals and metals) scored 1.856, while the freshwater ecotoxicity reached 80,317.23 CTUe, both driven by the nanoparticle production. The human toxicity potentials were 1.39 × 10−6 CTUh (cancer) and 7.45 × 10−5 CTUh (non-cancer), linked to emissions from synthesis and energy use. The LCA of the cosmetic cream revealed several critical areas of environmental impact. The most significant impacts are associated with gold nanoparticle synthesis and electricity use. Addressing these impacts through optimized synthesis processes, improved energy efficiency, and alternative materials can enhance the product’s sustainability profile significantly. Keywords: life cycle assessment, cosmetic cream, environmental impacts, gold nanoparticles Published in DKUM: 17.12.2024; Views: 0; Downloads: 9
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2. Hybrid nanostructures of ▫$Fe_3O_4$▫ and Au prepared via coprecipitation and ultrasonic spray pyrolysisLan Kresnik, Peter Majerič, Darja Feizpour, Klementina Pušnik Črešnar, Rebeka Rudolf, 2024, original scientific article Abstract: The coupled processes of coprecipitation and ultrasonic spray pyrolysis (USP) were used to synthesize Fe3O4-Au hybrid nanostructures. The first coprecipitation method enabled the synthesis of Fe3O4 nanoparticles by mixing iron salts’ ions (Fe2+ and Fe3+) and ammonia as the base, and USP was used as the coating process of the Fe3O4 nanoparticles with Au. The formatted hybrid nanostructures consist of Fe3O4 nanoparticles that have Au on their surface in the form of gold nanoparticles (AuNPs). AuNPs have a crystalline structure and range in size from 10 to 200 nm. Additional characterization techniques, including ICP-OES, TEM, SEM, EDS, DLS, zeta potential, and room temperature magnetic hysteresis loops, were used to determine the chemical, physical, and magnetic properties of the Fe3O4 nanoparticles and hybrid nanostructures. It was found that USP produces separate AuNPs too (not just on the Fe3O4 surface), suggesting a bimodal formation of AuNPs. The zeta potential of the Fe3O4 nanoparticles showed poor stability (−15 mV), indicating a high tendency to aggregate, and the zeta potential of the hybrid nanostructures was also very low (≅0), which, comparatively means even worse stability. The saturation magnetization of the Fe3O4 nanoparticles was 35 emu/g, which is relatively lower than that of bulk Fe3O4, while the saturation magnetization of the hybrid nanostructures was significantly lower (0.1 emu/g) compared to the Fe3O4 nanoparticles. Keywords: magnetic NPs, gold NPs, transmission electron microscopy, magnetic properties Published in DKUM: 29.11.2024; Views: 0; Downloads: 10
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3. Optical characteristics of directly deposited gold nanoparticle filmsJordi Sancho-Parramon, Tilen Švarc, Peter Majerič, Žiga Jelen, Rebeka Rudolf, 2024, original scientific article Abstract: The manuscript presents the optical properties of directly deposited films of gold nanoparticles (AuNPs) prepared by the Ultrasonic Spray Pyrolysis (USP) technology. Four samples were produced, with AuNP deposition times on the glass substrate of 15 min, 30 min, 1 h and 4 h. The morphological characterisation of the deposited films showed that the size of the first deposited AuNPs was between 10 and 30 nm, while, with a longer duration of the deposition process, larger clusters of AuNPs grew by coalescence and aggregation. The prepared layers were characterised optically with Ultraviolet–visible spectroscopy (UV–vis) and ellipsometry. The ellipsometric measurements showed an increasingly denser and thicker effective thickness of the AuNP layers. The extinction spectra displayed a clear local surface plasmonic resonance (LSPR) signature (peak 520–540 nm), indicating the presence of isolated particles in all the samples. For all AuNP layers, the imaginary part of the parallel and perpendicular components of the anisotropic dielectric function was dominated by a central peak at around 2.2 eV, corresponding to the LSPR of isolated particles, and a high-energy shoulder due to Au interband transitions. It was shown that, as the density of particles increased, the extinction cross-section grew over the whole spectral range where measurements are taken. Thus, the response can be explained with an enhanced electromagnetic response between the AuNPs that can be connected to the increase in particle density, but also by the formation of clusters and irregular structures. Keywords: optical characteristics, gold nanoparticles’ films, UV–vis, ellipsometry measurements Published in DKUM: 28.05.2024; Views: 124; Downloads: 0 |
4. Study of the application of recycled gold nanoparticles in coatings for eyewear lensesPeter Majerič, Djuro Koruga, Zorana Njegovan, Žiga Jelen, Tilen Švarc, Andrej Horvat, Rebeka Rudolf, 2023, original scientific article Keywords: gold nanoparticles, fullerene C60, lens, coatings, characterisation Published in DKUM: 28.03.2024; Views: 183; Downloads: 20
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5. Recovery study of gold nanoparticle markers from lateral flow immunoassaysTilen Švarc, Peter Majerič, Darja Feizpour, Žiga Jelen, Matej Zadravec, Timi Gomboc, Rebeka Rudolf, 2023, original scientific article Abstract: 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. Keywords: gold nanoparticles, recovery, LFIA, ultrasonic spray pyrolysis, characterisation Published in DKUM: 09.02.2024; Views: 358; Downloads: 20
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6. Polyvinylpyrrolidone-stabilised gold nanoparticle coatings inhibit blood protein adsorptionHanuma Reddy Tiyyagura, Matej Bračič, Rebeka Rudolf, 2024, original scientific article Abstract: 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. Keywords: gold nanoparticles, ultrasonic spray pyrolysis, haemocompatibility, protein adsorption, quartz crystal microbalance Published in DKUM: 30.01.2024; Views: 377; Downloads: 33
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7. Melting point of dried gold nanoparticles prepared with ultrasonic spray pyrolysis and lyophilisationŽiga Jelen, Marcin Krajewski, Franc Zupanič, Peter Majerič, Tilen Švarc, Ivan Anžel, Jernej Ekar, Sz-Chian Liou, Jerzy Kubacki, Mateusz Tokarczyk, Rebeka Rudolf, 2023, original scientific article Abstract: 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. Keywords: gold nanoparticles, melting point, ultrasonic spray pyrolysis, characterisation Published in DKUM: 08.12.2023; Views: 448; Downloads: 32
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8. Study of gold nanoparticles conjugated with SARS-CoV-2 S1 spike protein fragmentsŽiga Jelen, Janez Kovač, Rebeka Rudolf, 2023, original scientific article Abstract: 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. Keywords: gold nanoparticles, ultrasonic spray pyrolysis, conjugation, SARS-CoV-2 S1, characterisation Published in DKUM: 07.12.2023; Views: 416; Downloads: 22
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9. Physicochemical properties of gold nanoparticles for skin care creamsPeter Majerič, Zorana Jović, Tilen Švarc, Žiga Jelen, Andrej Horvat, Djuro Koruga, Rebeka Rudolf, 2023, original scientific article Abstract: 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. Keywords: gold nanoparticles, ultrasonic spray pyrolysis, freeze drying, characterization, creams Published in DKUM: 19.04.2023; Views: 769; Downloads: 79
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10. Small scale gold mining effects on the miners and local communities in semi-arid region of EthiopiaHailemariam Meaza, Mushir Ali, Solomon Hishe, Zbelo Tesfamariam, 2015, original scientific article Abstract: North Ethiopian highlands are traditionally known for gold mining which has been means of livelihood of the rural community. The present work was conducted to investigate socio- economic conditions of gold miners, ways of obtaining the gold, their earning and negative consequences of the gold mining. On the basis of random sampling, 140 miners were interviewed. Moreover, focus group discussions transect walks and practical observations across the mining sites were made with team leaders on different issues of gold mining and its effects. Descriptive statistics was used to compute socio-economic characteristics, gold harvesting, and income dynamics. ANOVA was run to observe variations of income from gold mining and other sources, 2009 to 2012. The positive effects of gold mining for involved people were regarding income, employment, expenditure on education, health and food consumption. On the other hand, conflicting interest, communicable diseases, aggressive child labour, school dropouts, social disruptions and injuries were challenges of the small scale gold mining. The findings highlight that the income generated from small scale gold mining plays a pivotal role in reducing rural poverty. Therefore, providing integrated training for gold miners can mitigate the challenges of small scale gold mining and thereby to improve livelihoods of the small scale gold miners in Ethiopia. Keywords: gold mining, indigenous methods, highlands, society, transaction, Ethiopia Published in DKUM: 16.04.2018; Views: 1126; Downloads: 100
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