1. The effects of ozone sterilization on the chemical and mechanical properties of 3D-printed biocompatible PMMAIvan Morosavljević, Dražan Kozak, Tihomir Kosor, Janko Morosavljević, Luka Ferlič, Nenad Gubeljak, 2024, izvirni znanstveni članek Opis: Since ozone is highly corrosive, it can substantially affect the mechanical and chemical properties of the materials; consequently, it could affect the applicability of those materials in medical applications. The effect of ozone sterilization on the chemical and mechanical properties of additively manufactured specimens of biocompatible poly(methyl-methacrylate) was observed. FDM 3D-printed specimens of biocompatible PMMA in groups of five were exposed to high concentrations of ozone generated by corona discharge for different durations and at different ozone concentrations inside an enclosed chamber with embedded and calibrated ozone, temperature, and humidity sensors. A novel approach using laser-induced fluorescence (LIF) and spark-discharge optical emission spectrometry (SD-OES) was used to determine an eventual change in the chemical composition of specimens. Mechanical properties were determined by testing the tensile strength and Young’s modulus. A calibrated digital microscope was used to observe the eventual degradation of material on the surface of the specimens. SD-OES and LIF analysis results do not show any detectable sterilizationcaused chemical degradation, and no substantial difference in mechanical properties was detected. There was no detectable surface degradation observed under the digital microscope. The results obtained suggest that ozone sterilization appears to be a suitable technique for sterilizing PMMA medical devices.
Ključne besede: ozone sterilization, poly(methyl-methacrylate) (PMMA), polymer oxidation, personalized medical device, environmentally friendly, fused deposition modeling (FDM)
Objavljeno v DKUM: 30.07.2025; Ogledov: 0; Prenosov: 1
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2. Efficient β-galactosidase immobilised on glycidyl methacrylate polyHIPEMuzafera Paljevac, Darja Pečar, Peter Krajnc, 2025, izvirni znanstveni članek Opis: Poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) monoliths (PolyGMA) were synthesized by high internal phase emulsion (HIPE) templating and polymerisation. The porous monoliths exhibited a hierarchical porous structure with primary pores (cavities, average diameter 35 µm) interconnected by secondary pores (average diameter 5 µm). FTIR spectroscopy confirmed the chemical composition and identified characteristic functional groups of both GMA and EGDMA. The polyGMA materials were ground and sieved to obtain particles between 710 µm and 1000 µm in diameter, which were subsequently used to immobilize the enzyme β-galactosidase. Immobilization was performed using two methods, namely direct binding via epoxide groups and binding after the activation with glutaraldehyde. The glutaraldehyde method resulted in higher enzyme loading (0.43 mg of enzyme per 100 mg of polyGMA) and significantly improved catalytic activity compared to direct binding. The immobilized β-galactosidase was used for lactose hydrolysis under various conditions using both batch and flow-through reactors. Optimal activity was observed at pH 6.5 and 35°C, with kinetic parameters vmax = 0.64 mmol∙L -1 ∙min-1 and �� = 38.8 mmol∙mol-1 . Reuse tests showed stable performance over five cycles. Comparatively, non-porous polyGMA exhibited negligible enzymatic activity compared to polyHIPE supported enzyme. In addition, lactose hydrolysis was investigated in a flow-through system at different flow rates (0.5–2.5 mL∙min- ¹). The highest conversion (100%) was observed at a flow rate of 0.5 mL∙min-¹, while a higher flow rate of 2.5 mL∙min-¹ resulted in a lower conversion (approx. 35%), both at the lactose concentration of 4 g∙L - ¹.
Ključne besede: immobilized enzymes, glycidyl methacrylate, polyHIPE, β-galactosidase, beta-galactosidase
Objavljeno v DKUM: 21.03.2025; Ogledov: 0; Prenosov: 10
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3. Multilayer methacrylate-based wound dressing as a therapeutic tool for targeted pain reliefTanja Zidarič, Kristijan Skok, Kristjan Orthaber, Matevž Pristovnik, Lidija Gradišnik, Tina Maver, Uroš Maver, 2023, izvirni znanstveni članek Opis: This study presents an innovative wound dressing system that offers a highly effective therapeutic solution for treating painful wounds. By incorporating the widely used non-steroidal anti-inflammatory drug diclofenac, we have created an active wound dressing that can provide targeted pain relief with ease. The drug was embedded within a biocompatible matrix composed of polyhydroxyethyl methacrylate and polyhydroxypropyl methacrylate. The multilayer structure of the dressing, which allows for sustained drug release and an exact application, was achieved through the layer-by-layer coating technique and the inclusion of superparamagnetic iron platinum nanoparticles. The multilayered dressings’ physicochemical, structural, and morphological properties were characterised using various methods. The synergistic effect of the incorporated drug molecules and superparamagnetic nanoparticles on the surface roughness and release kinetics resulted in controlled drug release. In addition, the proposed multilayer wound dressings were found to be biocompatible with human skin fibroblasts. Our findings suggest that the developed wound dressing system can contribute to tailored therapeutic strategies for local pain relief.
Ključne besede: wound dressings, pain relief, superparamagnetic nanoparticles, methacrylate
Objavljeno v DKUM: 19.04.2024; Ogledov: 485; Prenosov: 473
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4. Synthesis of PMMA/ZnO nanoparticles composite used for resin teethDanica Popović Antić, Rajko Bobovnik, Silvester Bolka, Miroslav Vukadinovič, Vojkan Lazić, Rebeka Rudolf, 2017, izvirni znanstveni članek Opis: Wear resistance is one of the most important physical properties of the artificial teeth used in acrylic dentures. The goal of this research was to synthesize a new composite material made of matrix Poly-(methyl methacrylate)-PMMA with different percentages (2 % and 3 % of volume fractions) of zinc-oxide nanoparticles (ZnO NPs) as reinforcing elements, to improve its mechanical properties. The dynamic mechanical behaviour of this composite was studied through the DMA method in comparison to the pure PMMA supported by the characterization of their microstructures. Then the wear resistance was analysed on the samples, which were prepared in the form of teeth. In this context their vertical height loss was measured after 100,000 chewing cycles on a chewing simulator, before and after the artificial thermal ageing. Investigations showed that the PMMA/ZnO NP composites dampened the vibrations better than the pure PMMA, which could be assigned to the homogenous distribution of ZnO NPs in the PMMA matrix. It was found that the mean vertical height loss for the pure PMMA teeth was significantly higher (more than 4 times) compared to composite teeth made with ZnO NPs. Introducing the thermal artificial ageing led to the finding that there was no effect on the height loss by the composite material with 3 % of volume fractions of ZnO NPs. Based on this it was concluded that PMMA/ZnO NPs composites showed improved in-vitro wear resistance compared to acrylic-resin denture teeth, so this new composite material should be preferred when occlusal stability is considered to be of high priority.
Ključne besede: poly-methyl methacrylate, PMMA, zinc-oxide nanoparticles, composite, resin teeth
Objavljeno v DKUM: 12.12.2017; Ogledov: 1876; Prenosov: 462
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5. Monolithic magneto-optical nanocomposites of barium hexaferrite platelets in PMMAGregor Ferk, Peter Krajnc, Anton Hamler, Alenka Mertelj, Federico Cebollada, Mihael Drofenik, Darja Lisjak, 2015, izvirni znanstveni članek Opis: The incorporation of magnetic barium hexaferrite nanoparticles in a transparent polymer matrix of poly(methyl methacrylate) (PMMA) is reported for the first time. The barium hexaferrite nanoplatelets doped with Sc3+, i.e., BaSc0.5Fe11.5O12 (BaHF), having diameters in the range 20 to 130 nm and thicknesses of approximately 5 nm, are synthesized hydrothermally and stabilized in 1-butanol with dodecylbenzenesulfonic acid. This method enables the preparation of monolithic nanocomposites by admixing the BaHF suspension into a liquid monomer, followed by in-situ, bulk free-radical polymerization. The PMMA retains its transparency for loadings of BaHF nanoparticles up to 0.27 wt.%, meaning that magnetically and optically anisotropic, monolithic nanocomposites can be synthesized when the polymerization is carried out in a magnetic field. The excellent dispersion of the magnetic nanoparticles, coupled with a reasonable control over the magnetic properties achieved in this investigation, is encouraging for the magneto-optical applications of these materials.
Ključne besede: polymer composites, nanoparticles, polymethyl methacrylate, PMMA
Objavljeno v DKUM: 23.06.2017; Ogledov: 1638; Prenosov: 462
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6. Mechanical properties of the materials for bruxoguardsVojkan Lazić, Aleksandra Špadijer Gostović, Nebojša Romčević, Igor Đorđević, Ana Todorović, Rebeka Rudolf, 2014, izvirni znanstveni članek Opis: The aim of this study is to investigate the mechanical properties of polymethyl methacrylate (PMMA) and thermoplastic polycarbonate (TPC) materials in order to produce night bruxoguards. For this purpose we used a static tensile test. In the next step the microstructures of PMMA and TPC were observed. Within this framework special attention was paid to the examination of the tensile-test tube fracture surfaces for both materials. This approach revealed that PMMA is a brittle and TPC is a plastic material. Certain mechanical properties and a review of the crucial areas confirmed that the TPC material is extremely favourable for making occlusal splints.
Ključne besede: polymers, mechanical properties, characterization, bruxoguards, polymethyl methacrylate, thermoplastic polycarbonate
Objavljeno v DKUM: 16.03.2017; Ogledov: 2295; Prenosov: 140
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7. Preparation and characterization of poly(high internal phase emulsion) methacrylate monoliths and their application as separation mediaPeter Krajnc, Nermina Leber, Dejan Štefanec, Sandra Kontrec, Aleš Podgornik, 2005, izvirni znanstveni članek Opis: Poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) monolithic supports were prepared by radical polymerisation of the continuous phase of water in oil high internal phase emulsions. Morphology of monolithic materialswas studied by scanning electron microscopy and mercury intrusion porosimetry. The ratio of phase volume and the degree of crosslinking influenced the void size and pore size distribution of resulting polymers. Void sizes between 1 and 10 m were observed and average pore sizes around 100nm. Polymers with 60, 75, 80 and 90% pore volume were prepared and even samples with highest pore volume showed good mechanical stability. They were modified to bear weak-anion exchange groups and tested on the separation of standard protein mixture containing myoglobin, conalbumine and trypsin inhibitor. Good separation was obtained in a very short time similar to the separation obtained by commercial methacrylate monoliths. However, higher dispersion was observed. Bovine serum albumin dynamic binding capacity for monolith with 90% porosity was close to 9 mg/ml.
Ključne besede: organic chemistry, methacrylate monoliths, preparation, emulsion polymerization, high porosity, high mechanical stability, polymer chromatographic supports, monolithic methacrylate supports, protein separation
Objavljeno v DKUM: 01.06.2012; Ogledov: 2570; Prenosov: 71
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