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Nanomaterials and their recent applications in impedimetric biosensing
Zala Štukovnik, Regina Fuchs-Godec, Urban Bren, 2023, pregledni znanstveni članek

Opis: Impedimetric biosensors measure changes in the electrical impedance due to a biochemical process, typically the binding of a biomolecule to a bioreceptor on the sensor surface. Nanomaterials can be employed to modify the biosensor's surface to increase the surface area available for biorecognition events, thereby improving the sensitivity and detection limits of the biosensor. Various nanomaterials, such as carbon nanotubes, carbon nanofibers, quantum dots, metal nanoparticles, and graphene oxide nanoparticles, have been investigated for impedimetric biosensors. These nanomaterials have yielded promising results in improving sensitivity, selectivity, and overall biosensor performance. Hence, they offer a wide range of possibilities for developing advanced biosensing platforms that can be employed in various fields, including healthcare, environmental monitoring, and food safety. This review focuses on the recent developments in nanoparticle-functionalized electrochemical-impedimetric biosensors.
Ključne besede: impedimetric biosensor, electrochemical impedance spectroscopy, nanomaterials, metal nanoparticles, carbon nanofibers, carbon nanotubes, graphene oxide, quantum dots
Objavljeno v DKUM: 12.02.2024; Ogledov: 59; Prenosov: 4
.pdf Celotno besedilo (3,14 MB)
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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: 61; Prenosov: 2
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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: 72; Prenosov: 4
.pdf Celotno besedilo (4,61 MB)
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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: 171; Prenosov: 12
.pdf Celotno besedilo (2,83 MB)
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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: 169; Prenosov: 9
.pdf Celotno besedilo (3,41 MB)
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Microwave Synthesis of Poly(Acrylic) Acid-Coated Magnetic Nanoparticles as Draw Solutes in Forward Osmosis
Sabina Vohl, Irena Ban, Mihael Drofenik, Hermina Bukšek, Sašo Gyergyek, Irena Petrinić, Claus Hélix-Nielsen, Janja Stergar, 2023, izvirni znanstveni članek

Opis: Polyacrylic acid (PAA)-coated magnetic nanoparticles (MNP@PAA) were synthesized and evaluated as draw solutes in the forward osmosis (FO) process. MNP@PAA were synthesized by microwave irradiation and chemical co-precipitation from aqueous solutions of Fe2+ and Fe3+ salts. The results showed that the synthesized MNPs have spherical shapes of maghemite Fe2O3 and superparamagnetic properties, which allow draw solution (DS) recovery using an external magnetic field. Synthesized MNP, coated with PAA, yielded an osmotic pressure of ~12.8 bar at a 0.7% concentration, resulting in an initial water flux of 8.1 LMH. The MNP@PAA particles were captured by an external magnetic field, rinsed in ethanol, and re-concentrated as DS in repetitive FO experiments with deionized water as a feed solution (FS). The osmotic pressure of the re-concentrated DS was 4.1 bar at a 0.35% concentration, resulting in an initial water flux of 2.1 LMH. Taken together, the results show the feasibility of using MNP@PAA particles as draw solutes.
Ključne besede: magnetic nanoparticles, microwave synthesis, polyacrilic acid, osmotic pressure, draw solution, forward osmosis
Objavljeno v DKUM: 05.12.2023; Ogledov: 179; Prenosov: 9
.pdf Celotno besedilo (3,00 MB)
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Pullulan-based films impregnated with silver nanoparticles from the Fusarium culmorum strain JTW1 for potential applications in the food industry and medicine
Magdalena Wypij, Mahendra Rai, Lidija Fras Zemljič, Matej Bračič, Silvo Hribernik, Patrycja Golińska, 2023, izvirni znanstveni članek

Opis: Introduction: Biopolymers, such as pullulan, a natural exopolysaccharide from Aureobasidium pullulans, and their nanocomposites are commonly used in the food, pharmaceutical, and medical industries due to their unique physical and chemical properties. Methods: Pullulan was synthesized by the A. pullulans ATCC 201253 strain. Nanocomposite films based on biosynthesized pullulan were prepared and loaded with different concentrations of silver nanoparticles (AgNPs) synthesized by the Fusarium culmorum strain JTW1. AgNPs were characterized by transmission electron microscopy, Zeta potential measurements, and Fourier-transform infrared spectroscopy. In turn, the produced films were subjected to physico-chemical analyses such as goniometry, UV shielding capacity, attenuated total reflection–Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, and their mechanical and degradation properties were assessed. The antibacterial assays of the nanoparticles and the nanocomposite films against both food-borne and reference pathogens, including Listeria monocytogenes, Salmonella infantis, Salmonella enterica, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae, were performed using standard methods. Results: AgNPs were small (mean 15.1 nm), spherical, and displayed good stability, being coated with protein biomolecules. When used in higher concentrations as an additive to pullulan films, they resulted in reduced hydrophilicity and light transmission for both UV-B and UV-A lights. Moreover, the produced films exhibited a smooth surface. Therefore, it can be concluded that the addition of biogenic AgNPs did not change the morphology and texture of the films compared to the control film. The nanoparticles and nanocomposite films demonstrated remarkable antibacterial activity against both food-borne and reference bacteria. The highest activity of the prepared films was observed against L. monocytogenes. Discussion: The obtained results suggest that the novel nanocomposite films prepared from biosynthesized pullulan and AgNPs can be considered for use in the development of medical products and food packaging. Moreover, this is the first report on pullulan-based nanocomposites with mycogenic AgNPs for such applications.
Ključne besede: Aureobasidium pullulans, pullulan, nanocomposite films, silver nanoparticles, mycosynthesis, nanobiotechnology, applied microbiology, antibacterial activity
Objavljeno v DKUM: 08.09.2023; Ogledov: 251; Prenosov: 14
.pdf Celotno besedilo (4,23 MB)
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Assessment of the Capability of Magnetic Nanoparticles to Recover Neodymium Ions from Aqueous Solution
Ana Ambrož, Irena Ban, Thomas Luxbacher, 2022, izvirni znanstveni članek

Opis: Magnetic nanoparticles (MNPs) have received increasing attention for various applications due to their fast synthesis, versatile functionalization, and recyclability by the application of a magnetic field. The high surface-to-volume ratio of MNP dispersions has suggested their use as an adsorbent for the removal of heavy metal ions. We investigated the applicability of MNPs composed of a maghemite core surrounded by a silica shell functionalized with aminopropylsilane, γ-Fe2O3-NH4OH@SiO2(APTMS), for the removal of neodymium ions (Nd3+) from aqueous solution. The MNPs were characterized for their size, composition, surface functionality and charge. Despite of the promising properties of MNPs, their removal from the aqueous dispersion with an external magnet was not sufficient to reliably quantify the adsorption of Nd3+ by UV-Vis spectroscopy.
Ključne besede: rare earth elements, maghemite, nanoparticles, UV-Vis spectroscopy, adsorption
Objavljeno v DKUM: 08.08.2023; Ogledov: 251; Prenosov: 20
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Synergistic effect of screen-printed Al(OH)[sub]3 nanoparticles and phosphorylated cellulose nanofibrils on the thermophysiological comfort and high-intensive heat protection properties of flame-retardant fabric
Tjaša Kolar, Jelka Geršak, Nataša Knez, Vanja Kokol, 2022, izvirni znanstveni članek

Opis: Al(OH)3 nanoparticles (ATH NPs) and phosphorylated cellulose nanofibrils (PCNFs) were used as user-friendly and comfortable coating components on flame-retardant fabric to improve its thermophysiological comfort and high-intensive heat protection properties. The effect of the PCNF imprinting and its attachment after the post-printing of a hydrophobic polyacrylate (AP) on the same (back side) or the other (front) side of the fabric, with and without the addition of ATH NPs, was considered, to maintain the front side (facing the wearer) as hydrophilic while keeping the back side (facing the outside) hydrophobic. The amount of coatings applied and their patterning were studied, varied with the ATH NPs’ concentration (1.7, 3.3 and 6.7 wt%) and screen mesh size used (60 and 135), based on the coating’ mass, fabric’s air permeability, thickness and microstructure. The reduced moisture build-up (55%), increased the water vapour (13%) and heat (12%) transfer from the skin, were assessed by applying PCNF under the AP, being more pronounced in the case of using a 135 mesh-sized screen, given the smaller, more densely distributed, thinner and imprinted pattern coatings. These effects were further improved by the addition of nanoporous ATH NPs, which allowed more homogeneous spreading of the moisture and its faster transport. Such a treatment also shifted the fabric’s degradation temperature towards higher values (up to 15°C), retained up to 30% of high-heat flux (21 kW/m2), prolonged the time to ignition by 11 s and reduced the total heat released by up to 60%, thereby providing better protection when exposed to the heat, due to the presence of the phosphorous (PCNF) promoted generation of an Al2O3 char acting as a barrier layer, while also reducing the production of heat and generation of smoke by 75%.
Ključne besede: tekstilna tehnologija, ognjevaren tekstil, Al(OH)3 nanodelci, celulozni nanofibrili, tiskanje tekstilij, optične lastnosti, termofiziološko udobje, toplotna zaščita, flame-retardant textile, Al(OH)3 nanoparticles, phosphorylated cellulose nanofibrils, screen-printing, thermophysiological comfort, heat protection
Objavljeno v DKUM: 12.07.2023; Ogledov: 271; Prenosov: 8
.pdf Celotno besedilo (2,91 MB)
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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: 467; Prenosov: 41
.pdf Celotno besedilo (5,34 MB)
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