1. Synthesis of complex concentrated nanoparticles by Ultrasonic Spray Pyrolysis and lyophilisationLidija Simić, Srečko Stopić, Bernd Friedrich, Matej Zadravec, Žiga Jelen, Rajko Bobovnik, Ivan Anžel, Rebeka Rudolf, 2022, izvirni znanstveni članek Opis: The development of new multicomponent nanoparticles is gaining increasing importance
due to their specific functional properties, i.e., synthesised new complex concentrated nanoparticles
(CCNPs) in the form of powder using ultrasonic spray pyrolysis (USP) and lyophilisation from the
initial cast Ag20Pd20Pt20Cu20Ni20 alloy, which was in the function of the material after its catalytic
abilities had been exhausted. Hydrometallurgical treatment was used to dissolve the cast alloy,
from which the USP precursor was prepared. As a consequence of the incomplete dissolution of
the cast alloy and the formation of Pt and Ni complexes, it was found that the complete recycling
of the alloy is not possible. A microstructural examination of the synthesised CCNPs showed that
round and mostly spherical (not 100%) nanoparticles were formed, with an average diameter of
200 nm. Research has shown that CCNPs belong to the group with medium entropy characteristics.
A mechanism for the formation of CCNPs is proposed, based on the thermochemical analysis of
element reduction with the help of H2 and based on the mixing enthalpy of binary systems.
Ključne besede: complex concentrated nanoparticles, ultrasonic spray pyrolysis, lyophilisation, characterization, formation mechanism
Objavljeno v DKUM: 24.03.2025; Ogledov: 0; Prenosov: 2
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2. Synthesis of Ni/Y2O3 nanocomposite through USP and lyophilisation for possible use as coatingTilen Švarc, Srečko Stopić, Žiga Jelen, Matej Zadravec, Bernd Friedrich, Rebeka Rudolf, 2022, izvirni znanstveni članek Opis: The Ni/Y2O3 catalyst showed high catalytic activity. Based on this, the aim of this study
was to create Ni/Y2O3 nanocomposites powder with two innovative technologies, Ultrasonic Spray
Pyrolysis (USP) and lyophilisation. In the USP process, thermal decomposition of the generated
aerosols in an N2/H2 reduction atmosphere caused a complete decomposition of the nickel (II) nitrate
to elemental Ni, which became trapped on the formed Y2O3 nanoparticles. The Ni/Y2O3 nanocomposite particles were captured via gas washing in an aqueous solution of polyvinylpyrrolidone (PVP)
in collection bottles. PVP was chosen for its ability to stabilise nano-suspensions and as an effective
cryoprotectant. Consequently, there was no loss or agglomeration of Ni/Y2O3 nanocomposite material during the lyophilisation process. The Ni/Y2O3 nanocomposite powder was analysed using
ICP-MS, SEM-EDX, and XPS, which showed the impact of different precursor concentrations on the
final Ni/Y2O3 nanocomposite particle composition. In a final step, highly concentrated Ni/Y2O3
nanocomposite ink (Ni/Y2O3 > 0.140 g/mL) and test coatings from this ink were prepared by applying them on a white matte photo paper sheet. The reflection curve of the prepared Ni/Y2O3
nanocomposite coating showed a local maximum at 440 nm with a value of 39% reflection. Given that
Ni is located on the surface of the Ni/Y2O3 nanocomposite in the elemental state and according to the
identified properties, tests of the catalytic properties of this coating will be performed in the future.
Ključne besede: Ultrasonic Spray Pyrolysis (USP), lyophilisation, Ni/Y2O3 nanocomposite, characterisation, coatings
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 5
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3. Nisin-loaded gelatin microparticles for the enhanced bioactivity of bacterial nanocelluloseMaša Hren, Janja Trček, Aleksandra Šakanović, Hristina Obradović, Mateja Erdani-Kreft, Silvo Hribernik, Selestina Gorgieva, 2025, izvirni znanstveni članek Opis: Bacterial nanocellulose (BnC) is of immense importance in medicine, although its lack of bioactivity present intriguing issue. We propose a method to modify BnC with gelatin and nisin biomolecules, and explore their synergistic effect on the antimicrobial activity. Gelatin microparticles (without/with nisin loading) with a size ~0.5 μm and ~ 1.3 μm were prepared by spray drying and stabilised by dehydrothermal treatment. Modified BnC-based membranes supported the formation of biologically relevant minerals and were non-cytotoxic to human gingival fibroblast cells (HGF). The presence of gelatin microparticles improved the viability of HGF by approximately 20 %, due to the effect of gelatin alone, independent of the addition of nisin. BnC coated with a nisin/gelatin solution reduces the viability of HGF by about 20 %, but this negative effect is not observed by nisin coated gelatin microparticles. The cell viability of BnC membranes was above 90 % in both porcine and human urothelial cells. The antimicrobial activity study confirmed an inhibitory effect of membranes modified with nisin-coated microparticles or a gelatin/nisin solution against Staphylococcus aureus at a non-cytotoxic nisin dose (150 μg/mL). The study demonstrates the structural effects of gelatin and gelatin/nisin mixtures on the bioactivity of BnC and provides a rationale for the modification procedure.
Ključne besede: bacterial nanocellulose, gelatin, nisin, spray-drying, antimicrobial function, bioactivity
Objavljeno v DKUM: 10.03.2025; Ogledov: 0; Prenosov: 8
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4. Functionalization of surgical mask polypropylene layers with application of natural substancesMarjana Simonič, Olivija Plohl, Maša Vračevič, Lidija Fras Zemljič, 2025, izvirni znanstveni članek Opis: The anti-viral efficacy of face mask was enhanced by applying the protein lactoferrin, the polyphenol catechin individually, and in combination. Individual solutions of protein and polyphenol were meticulously prepared and subsequently sprayed onto the inner surface of face mask layers composed of polypropylene. The functionalized mask layers were subjected to comprehensive characterization through Fourier transform infrared spectroscopy, zeta-potential measurements, and X-ray photoelectron spectroscopy. Goniometry was employed to assess the wettability of the modified surface layer, and air permeability was quantified both before and after the application of potential anti-viral agents. Bioactivity, such as anti-oxidant activity using ABTS assay and anti-viral efficiency against the model virus phi6, was followed as well. Our findings indicate the successful modification of mask with lactoferrin, while functionalization by catechin proved to be unsuccessful. The measured contact angles underscored the hydrophobic nature of the functionalized samples, ensuring reduced wettability in the presence of saliva droplets. Notably, the individual coating layers exhibited enhanced anti-oxidant activity and demonstrated anti-viral properties against the model virus phi6, when the outer layer of the mask was spray-coated. These results suggest promising technology to integrating these functionalized layers into masks for enhanced safety performance.
Ključne besede: catechin, lactoferrin, PP mask, spray-coating, anti-viral properties
Objavljeno v DKUM: 07.02.2025; Ogledov: 0; Prenosov: 3
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5. Study of ▫$Ni/Y_2O_3/polylactic$▫ acid compositeTilen Švarc, Matej Zadravec, Žiga Jelen, Peter Majerič, Blaž Kamenik, Rebeka Rudolf, 2023, izvirni znanstveni članek Opis: This study demonstrates the successful synthesis of Ni/Y2O3 nanocomposite particles through the application of ultrasound-assisted precipitation using the ultrasonic spray pyrolysis technique. They were collected in a water suspension with polyvinylpyrrolidone (PVP) as the stabiliser. The presence of the Y2O3 core and Ni shell was confirmed with transmission electron microscopy (TEM) and with electron diffraction. The TEM observations revealed the formation of round particles with an average diameter of 466 nm, while the lattice parameter on the Ni particle’s surface was measured to be 0.343 nm. The Ni/Y2O3 nanocomposite particle suspensions were lyophilized, to obtain a dried material that was suitable for embedding into a polylactic acid (PLA) matrix. The resulting PLA/Ni/Y2O3 composite material was extruded, and the injection was moulded successfully. Flexural testing of PLA/Ni/Y2O3 showed a slight average decrease (8.55%) in flexural strength and a small decrease from 3.7 to 3.3% strain at the break, when compared to the base PLA. These findings demonstrate the potential for utilising Ni/Y2O3 nanocomposite particles in injection moulding applications and warrant further exploration of their properties and new applications in various fields.
Ključne besede: ultrasound spray pyrolysis, Ni/Y2O3, lyophilization, PLA, extrusion, injection moulding
Objavljeno v DKUM: 05.04.2024; Ogledov: 199; Prenosov: 22
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6. Comparison of surface and spectral properties of optical sensor layers prepared by spin/spray coating and printing techniquesNena Dimitrušev, Polonca Nedeljko, Allwin Mabes Raj, Aleksandra Lobnik, 2023, izvirni znanstveni članek Ključne besede: optical sensor layers preparation, spin coating, spray coating, inkjet printing, SFE, XPS, NH3, response, real-time response
Objavljeno v DKUM: 28.03.2024; Ogledov: 198; Prenosov: 13
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7. Recovery study of gold nanoparticle markers from lateral flow immunoassaysTilen 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: 358; Prenosov: 24
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8. Polyvinylpyrrolidone-stabilised gold nanoparticle coatings inhibit blood protein adsorptionHanuma 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: 377; Prenosov: 33
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9. 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, 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: 448; Prenosov: 32
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10. Study of gold nanoparticles conjugated with SARS-CoV-2 S1 spike protein fragmentsŽiga 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: 416; Prenosov: 26
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