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Polyester type polyHIPE scaffolds with an interconnected porous structure for cartilage regeneration
Jakob Naranda, Maja Sušec, Uroš Maver, Lidija Gradišnik, Mario Gorenjak, Andreja Vukasović, Alan Ivković, Marjan Rupnik, Matjaž Vogrin, Peter Krajnc, 2016, izvirni znanstveni članek

Opis: Development of artificial materials for the facilitation of cartilage regeneration remains an important challenge in orthopedic practice. Our study investigates the potential for neocartilage formation within a synthetic polyester scaffold based on the polymerization of high internal phase emulsions. The fabrication of polyHIPE polymer (PHP) was specifically tailored to produce a highly porous (85%) structure with the primary pore size in the range of 50–170 μm for cartilage tissue engineering. The resulting PHP scaffold was proven biocompatible with human articular chondrocytes and viable cells were observed within the materials as evaluated using the Live/Dead assay and histological analysis. Chondrocytes with round nuclei were organized into multicellular layers on the PHP surface and were observed to grow approximately 300 μm into the scaffold interior. The accumulation of collagen type 2 was detected using immunohistochemistry and chondrogenic specific genes were expressed with favorable collagen type 2 to 1 ratio. In addition, PHP samples are biodegradable and their baseline mechanical properties are similar to those of native cartilage, which enhance chondrocyte cell growth and proliferation.
Ključne besede: polyester, polymerization, polyHIPE
Objavljeno: 23.06.2017; Ogledov: 12; Prenosov: 0
.pdf Polno besedilo (1,24 MB)

Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applications
Matjaž Finšgar, Amra Perva-Uzunalić, Janja Stergar, Lidija Gradišnik, Uroš Maver, 2016, izvirni znanstveni članek

Opis: Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys.
Ključne besede: corrosion, corrosion resistance, chitosan, biocompatibility, biomaterials, biomedical materials, coatings, stainless steel
Objavljeno: 23.06.2017; Ogledov: 9; Prenosov: 0
.pdf Polno besedilo (2,73 MB)

Monolithic magneto-optical nanocomposites of barium hexaferrite platelets in PMMA
Mihael Drofenik, Gregor Ferk, Anton Hamler, Peter Krajnc, Darja Lisjak, Alenka Mertelj, Federico Cebollada, 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: 23.06.2017; Ogledov: 9; Prenosov: 0
.pdf Polno besedilo (1,10 MB)

Polyphenols: extraction methods, antioxidative action, bioavailability and anticarcinogenic effects
Eva Brglez Mojzer, Maša Knez Hrnčič, Mojca Škerget, Željko Knez, Urban Bren, 2016, izvirni znanstveni članek

Opis: Being secondary plant metabolites, polyphenols represent a large and diverse group of substances abundantly present in a majority of fruits, herbs and vegetables. The current contribution is focused on their bioavailability, antioxidative and anticarcinogenic properties. An overview of extraction methods is also given, with supercritical fluid extraction highlighted as a promising eco-friendly alternative providing exceptional separation and protection from degradation of unstable polyphenols. The protective role of polyphenols against reactive oxygen and nitrogen species, UV light, plant pathogens, parasites and predators results in several beneficial biological activities giving rise to prophylaxis or possibly even to a cure for several prevailing human diseases, especially various cancer types. Omnipresence, specificity of the response and the absence of or low toxicity are crucial advantages of polyphenols as anticancer agents. The main problem represents their low bioavailability and rapid metabolism. One of the promising solutions lies in nanoformulation of polyphenols that prevents their degradation and thus enables significantly higher concentrations to reach the target cells. Another, more practiced, solution is the use of mixtures of various polyphenols that bring synergistic effects, resulting in lowering of the required therapeutic dose and in multitargeted action. The combination of polyphenols with existing drugs and therapies also shows promising results and significantly reduces their toxicity.
Ključne besede: polyphenols, extraction, antioxidants, bioavailability, synergistic effects
Objavljeno: 22.06.2017; Ogledov: 11; Prenosov: 0
.pdf Polno besedilo (1,38 MB)

Separation of peptides with forward osmosis biomimetic membranes
Niada Bajraktari, Henrik T. Madsen, Mathias F. Gruber, Sigurd Truelsen, Elzbieta L. Jensen, Henrik Jensen, Claus Hélix-Nielsen, 2016, izvirni znanstveni članek

Opis: Forward osmosis (FO) membranes have gained interest in several disciplines for the rejection and concentration of various molecules. One application area for FO membranes that is becoming increasingly popular is the use of the membranes to concentrate or dilute high value compound solutions such as pharmaceuticals. It is crucial in such settings to control the transport over the membrane to avoid losses of valuable compounds, but little is known about the rejection and transport mechanisms of larger biomolecules with often flexible conformations. In this study, transport of two chemically similar peptides with molecular weight (Mw) of 375 and 692 Da across a thin film composite Aquaporin Inside™ Membrane (AIM) FO membrane was investigated. Despite the relative large size, both peptides were able to permeate the dense active layer of the AIM membrane and the transport mechanism was determined to be diffusion-based. Interestingly, the membrane permeability increased 3.65 times for the 692 Da peptide (1.39 × 10−12 m2·s−1) compared to the 375 Da peptide (0.38 × 10−12 m2·s−1). This increase thus occurs for an 85% increase in Mw but only for a 34% increase in peptide radius of gyration (Rg) as determined from molecular dynamics (MD) simulations. This suggests that Rg is a strong influencing factor for membrane permeability. Thus, an increased Rg reflects the larger peptide chains ability to sample a larger conformational space when interacting with the nanostructured active layer increasing the likelihood for permeation.
Ključne besede: forward osmosis, biomimetic, peptides, rejection
Objavljeno: 21.06.2017; Ogledov: 23; Prenosov: 0
.pdf Polno besedilo (2,21 MB)

Challenges in commercializing biomimetic membranes
Mark Edward Perry, Steen Ulrik Madsen, Tine Jørgensen, Sylvia Braekevelt, Karsten Lauritzen, Claus Hélix-Nielsen, 2015, pregledni znanstveni članek

Opis: The discovery of selective water channel proteins-aquaporins-has prompted growing interest in using these proteins, as the building blocks for designing new types of membranes. However, as with any other new and potentially disruptive technology, barriers for successful market entry exist. One category includes customer-related barriers, which can be influenced to some extent. Another category includes market-technical-related barriers, which can be very difficult to overcome by an organization/company aiming at successfully introducing their innovation on the market%in particular if both the organization and the technology are at early stages. Often, one faces barriers from both these categories at the same time, which makes it necessary to gain insight of the particular market when introducing a new innovative product. In this review we present the basic concepts and discuss some of these barriers and challenges associated with introducing biomimetic aquaporin membranes. These include technical issues in membrane production and product testing. Then we discuss possible business models for introducing new technologies in general, followed by a presentation of beach-head market segments relevant for biomimetic aquaporin membranes.
Ključne besede: aquaporin membranes, biomimetic, commercialization, early stage technology
Objavljeno: 21.06.2017; Ogledov: 17; Prenosov: 0
.pdf Polno besedilo (239,48 KB)

Aquaporin-based biomimetic polymeric membranes
Claus Hélix-Nielsen, Joachim Habel, Michael R. Hansen, Søren Kynde, Nanna Larsen, Søren Roi Midtgaard, Grethe Vestergaard Jensen, Julie Bomholt, Anayo Ogbonna, Kristoffer Almdal, Alexander Schulz, 2015, pregledni znanstveni članek

Opis: In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs: aquaporin proteins (AQPs), block copolymers for AQP reconstitution, and polymer-based supporting structures. First, we briefly cover challenges and review recent developments in understanding the interplay between AQP and block copolymers. Second, we review some experimental characterization methods for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes.
Ključne besede: aquaporins, biomimetic membranes, block copolymers, proteopolymersomes, polyhedral oligomeric silsesquioxanes, polyamide layer, microfluidics, membrane proteins, protein-polymer-interactions
Objavljeno: 21.06.2017; Ogledov: 20; Prenosov: 0
.pdf Polno besedilo (10,59 MB)

Uporaba biomimetičnih membran pri koncentriranju naravnih sokov
Mateja Pulko, 2017, diplomsko delo/naloga

Opis: Za koncentriranje naravnih sokov uporabljamo različne procese. V diplomskem delu smo za koncentriranje želeli uporabljati proces osmoze, saj se proces zdi uspešen in ekonomičen. Procesu osmoze že posvečajo veliko pozornosti pri čiščenju odpadnih voda, pridobivanju pitne vode in tudi za prehrambeno industrijo. Namen našega dela je bil koncentrirati naravni pomaranči sok s procesom osmoze in s pomočjo biomimetične membrane. Za delo smo uporabili biomimetično membrano, za katero je značilno, da ima vgrajene proteine akvaporine, ki omogočajo hitrejši prenos snovi in hkrati zavirajo povratni tok topljenca. Eksperimente smo izvajali tako, da smo si izbrali različne pogonske raztopine, kot so NaCl, CaCl2, MgCl2 in NaCl v kombinaciji s saharozo, med katerimi smo želeli določiti idealno pogonsko raztopino za proces koncentriranj pomarančnega soka. Za vhodno raztopino smo uporabljali ultra čisto vodo, kombinacijo sladkorjev in sveže iztisnjen pomarančni sok. Med procesom osmoze je bila aktivna plast biomimetične membrane v stiku z vhodno raztopino, kar je omogočalo hitrejši pretok. Delo je potekalo s konstantno hitrostjo črpalk pri sobni temperaturi. Merili smo spremembo mase in prevodnosti vhodne raztopine. Rezultate dela smo prikazali na grafih pretoka v odvisnosti od časa.
Ključne besede: biomimetične membrane, osmoza, koncentriranje sokov, pogonska raztopina, osmotski tlak
Objavljeno: 19.06.2017; Ogledov: 10; Prenosov: 3
.pdf Polno besedilo (2,60 MB)

Anže Šimic, 2016, diplomsko delo/naloga

Opis: Namen mojega diplomskega dela je bil sintetizirati in preučiti različne multifunkcionalne spojine, ki vsebujejo Sn. Dodatni namen je bil boljše razumevanje procesa sol-gel v povezavi s Sn spojinami. Glavna motivacija te raziskave je bilo odkrivanje narave in lastnosti zemeljsko alkalijskih stanatov z dodanimi Eu3+ ioni in pri tem iskanje novih anorganskih nosilcev za učinkovito lantanidno vcepitev. Iz tega razloga so bile formulirane sledeče naloge: -Predlagati nov sintetični pristop k pripravi enotnih SnO2 filmov, kateri izvirajo iz čiste raztopine, ki ne vsebuje ionov, ki bi se vmešavali, je v nevtralnem mediju in uporablja vodo kot topilo. Tudi karakterizacija Sn(IV) gel prekurzorja. -Predlagati nov in trpežen sintetični pristop za pripravo zemeljsko alkalijsko kovinskih Sr stanatov z vodno sol-gel metodo. -Raziskati fotoluminescenčne lastnosti Eu3+ z dodanimi zemeljsko alkalijskimi stanatnimi fosforji, pripravljenimi z metodo sol-gel. -Preučevanje nanostrukturiranih keramik Srn+1SnnO3n+1 (n = ∞, 1 in 2)
Ključne besede: sol-gel, zemeljsko alkalijske spojine, stanati
Objavljeno: 19.06.2017; Ogledov: 7; Prenosov: 2
.pdf Polno besedilo (1,44 MB)

High-resolution melting curve analysis for high-throughput genotyping of NOD2/CARD15 mutations and distribution of these mutations in Slovenian inflammatory bowel diseases patients
Mitja Mitrovič, Uroš Potočnik, 2011, izvirni znanstveni članek

Opis: Inflammatory bowel diseases (IBD) are usually classified into Crohn's disease (CD) and ulcerative colitis (UC). NOD2/CARD15 was the first identified CD-susceptibility gene and was confirmed as the most potent disease gene in CD pathogenesis. Three NOD2/CARD15 variants, namely two missense polymorphisms R702W (rs2066844) and G908R (rs2066845), and a frame shift polymorphism L1007fs (rs2066847), were associated with CD in Caucasian populations. High resolution melting analysis (HRMA) with saturation LCGreen dyes was previously reported as a simple, inexpensive, accurate and sensitive method for genotyping and/or scanning of rare variants. For this reasons we used qPCR-HRMA for genotyping NOD2/CARD15 variants in 588 Slovenian IBD patients and 256 healthy controls. PCR-RFLP was used as a reference method for genotyping of clinical samples. The optimization of an HRM experiment required careful design and adjustment of main parameters, such as primer concentration, MgCl_{2} concentration, probe design and template DNA concentration. Different HRMA approaches were tested and used to develop a reliable and low-cost SNP genotyping assays for polymorphisms in NOD2/CARD15 gene. Direct HRMA was the fastest and cheapest HRMA approach for L1007fs and R702W polymorphisms, yet for G908R polymorphism sufficient reliability was achieved after introduction of unlabeled probe. In association analysis, we found statistically significant association of L1007fs (p =0.001, OR=3.011, CI95%=1.494-6.071) and G908R (p=2.62 * 10^{-4}, OR=14.117, CI95%= 1.884-105.799) polymorphisms with CD patients. At least one of NOD2/CARD15 polymorphisms was found in 78/354 (22.03% (12.69%) in UC patients and in 26/256 (10.15%) in healthy controls. We have successfully implemented NOD2/CARD15 HRMA assays, which may contribute to the development of genetic profiles for risk prediction of developing CD and for differential diagnosis of CD vs. UC.
Ključne besede: high-resolution melting analysis, NOD2/CARD15, inflammatory bowel diseases
Objavljeno: 14.06.2017; Ogledov: 15; Prenosov: 0
.pdf Polno besedilo (1,72 MB)

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