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Opis: Poleg sorte, geo-klimatskih pogojev in vinogradniških strategij v vinogradu so tudi vinarjeve odločitve glede izbora vinifikacijskih postopkov tiste, ki lahko odločilno vplivajo na končno kakovost vina, vključno z njegovimi aromatskimi značilnostmi. Z različnimi prijemi ali postopki pred alkoholno fermentacijo in med njo lahko vplivamo predvsem na ekstrakcijo in ohranitev primarnih ter na tvorbo sekundarnih aromatskih spojin. V okviru diplomskega dela smo s pomočjo modernih analitskih pristopov metabolnega profiliranja in tehnike GC/MS/MS preučevali vpliv različnih tehnoloških postopkov predelave grozdja (krioekstrakcija s suhim ledom, stik s celimi jagodami med fermentacijo, klasični pristop-kontrola) na vsebnost prostih in vezanih aromatičnih spojin v mladih vinih Zelen, letnik 2014. Preučili smo tudi vpliv obravnavanih tehnologij na senzorične lastnosti, vezane na zaznave vonja v mladih vinih. Rezultati enoletnega poskusa so nakazali, da lahko s pomočjo krioekstrakcije v vinih Zelen povečamo izplene skupnih prostih aromatičnih kislin, estrov in terpenov, po drugi strani pa smo zaznali le trend povečanja vsebnosti skupnih višjih alkoholov pri vzorcih iz postopka dodajanja jagod med fermentacijo. V primeru vezanih aromatskih spojin smo s pomočjo postopka dodajanja jagod v primerjavi s kontrolo opazili trende povečanja vsebnosti nekaterih vezanih estrov, norizoprenoidov in višjih alkoholov, krioekstrakcija pa je večinoma povzročila trende k niţjim vsebnostim vezanih aromatskih spojin glede na kontrolne vzorce. Nazadnje so se tudi senzorična opazovanja z vonjem povezanih lastnosti vin zaključila preteţno v prid postopku z dodajanjem jagod med fermentacijo.
Ključne besede: 'Zelen' (Vitis Vinifera L.), alternativni pristopi v predelavi grozdja, krioekstrakcija, dodajanje sveţih jagod med alkoholno fermentacijo, proste aromatične spojine v vinu, vezane aromatične spojine v vinu, senzorika vina
Objavljeno v RUNG: 23.01.2017; Ogledov: 7575; Prenosov: 316
Celotno besedilo (1,16 MB)

Opis: A novel, simple method was developed to synthesize biocompatible composites containing 50% cellulose (CEL) and 50% keratin (KER) and silver in the form of either ionic (Ag+) or Ag0 nanoparticle (Ag+NPs or Ag0NPs). In this method, butylmethylimmidazolium chloride ([BMIm+Cl-]), a simple ionic liquid, was used as the sole solvent and silver chloride was added to the [BMIm+Cl-] solution of [CEL+KER] during the dissolution process. The silver in the composites can be maintained as ionic silver (Ag+) or completely converted to metallic silver (Ag0) by reducing it with NaBH4. Results of spectroscopy (Fourier-transform infrared (FTIR), X-ray diffraction (XRD)) and imaging (scanning electron microscope (SEM)) measurements confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. Powder X-ray diffraction (XRD) and SEM results show that the silver in the [CEL+KER+Ag+] and [CEL+KER+Ag0] composites is homogeneously distributed throughout the composites in either Ag+ (in the form of Ag2O nanoparticles (NPs)) or Ag0NPs form with size of (9 ± 1) nm or (27 ± 2) nm, respectively. Both composites were found to exhibit excellent antibacterial activity against many bacteria including Escherichia coli, Staphylococus aureus, Pseudomonas aeruginosa, methicillin resistant Staphylococus aureus (MRSA), vancomycin resistant Enterococus faecalis (VRE). The antibacterial activity of both composites increases with the Ag+ or Ag0 content in the composites. More importantly, for the same bacteria and the same silver content, [CEL+KER+Ag0] composite exhibits relatively greater antimicrobial activity against bacteria compared to the corresponding [CEL+KER+Ag+] composite. Experimental results confirm that there was hardly any Ag0NPs release from the [CEL+KER+Ag0NPs] composite, and hence its antimicrobial activity and biocompatibility is due, not to any released Ag0NPs but rather entirely to the Ag0NPs embedded in the composite. Both Ag2ONPs or Ag0NPs were found to be toxic to human fibroblasts at higher concentration (>0.72 mmol), and that for the same silver content, [CEL+KER+Ag2ONPs] composite is relatively more toxic than [CEL+KER+Ag0NPs] composite. As expected, by lowering the Ag0NPs concentration to 0.48 mmol or less, the [CEL+KER+Ag0NPs] composite can be made biocompatible while still retaining its antimicrobial activity against bacteria such are E. coli, S. aureus, P. aeruginosa, MRSA, VRE. These results together with our previous finding that [CEL+KER] composites can be used for controlled delivery of drugs such as ciprofloxacin clearly indicate that the [CEL+KER+Ag0NPs] composite possess all required properties for successfully used as high performance dressing to treat chronic ulcerous infected wounds.
Ključne besede: Celulose, Keratin, Cmposites, Biocompatible, Ag nanoparticles, one-pot synthesis, Antibacterial, Antiviral
Objavljeno v RUNG: 28.11.2016; Ogledov: 5071; Prenosov: 0
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Opis: Detection in microfluidic systems requires highly sensitive analytical methods, because of the very short optical interaction length, which is usually in the range of 100 μm or shorter. Furthermore, the amounts of analytes in detection volumes are extremely small (femto- or attomoles). Thermal lens spectrometry and particularly thermal lens microscopy (TLM) appear as techniques of choice for detection in microfluidic and lab-on-a-chip systems, since they enable measurements of absorbance’s or absorbance changes as low as 10-7. In addition to ultra-high sensitivity, TLM offers high spatial resolution (≈1 μm) and sufficient temporal resolution (ms range), which is required for studies of processes in microfluidic systems. Recent development of TLM theory and instrumentation lead to experimental confirmations of the effects of microfluidic flows on the TLM signal, which affects the sensitivity. On the other hand, these observations have enabled optimization of TLM instruments [1]. As a result of these advancements, applications of TLM were extended from simple laminar flows [2], to highly complex systems such as Tylor-type flows, where TLM detection provided data for description of diffusion processes in n-octane/methanol binary liquid systems [3]. The major streamline of TLM applications was however focused on the development of vanguard analytical systems [4], which are needed in various fields of chemical analysis, including food safety and quality control, environmental monitoring as well as biomedical research and diagnostics. Such systems are used as sample screening systems (sample filters or selectors) when the information is needed quickly to make immediate decisions in relation to the analytical problem. They provide simplicity (e.g. little or no sample pre-treatment), low cost, rapid and reliable response, and frequently give just binary responses. However, their major weakness is low metrological quality of results. Therefore, uncertainties of up to 5–15% are usually accepted as a toll for rapidity and simplicity, which are essential even though in contradiction with conventional analytical concepts. With the objective of developing new vanguard analytical systems, a relevant goal is to exploit the advantages offered by microfluidic lab-on-a-chip systems on one hand, and TLM detection on the other. In such combinations, the FIA approach simplifies sample handling (e.g. volume measurements) and transport to the detector, while microfluidic lab-on-a-chip technology can facilitate and speed up processes including colorimetric reactions, antigen–antibody or enzyme–substrate interactions in bioanalytical systems, and even extraction and preconcentration steps by introducing continuous flow processing and micro unit operations in chemical analysis [2]. High sensitivity of TLM in such systems offers low limits of detection, which also contribute to low uncertainties that are typically below 10%. An important advantage of microfluidic systems lies in the fact that small dimensions of such systems, which consist of capillaries and micro reactors with dimensions about 10 to 100 μm, significantly reduce the molecular diffusion time, which is inversely proportional to the second power of distance. For example, the time required for completion of an ELISA immunoassay for NGAL a biomarker of acute kidney failure was reduced from four hours to only 30 mins. [5, 6] when transferring the assay into a microfluidic system, while maintaining or even improving the sensitivity. Even more evident improvement in sample throughput (reduction of analysis time from 10 hours to 30 minutes) was achieved for determination of antibodies for human papilloma virus (anti L1 HPV 16) in blood plasma, after immobilizing adequate pseudovirions as antigens on magnetic nanobeads [6]. Other health-related applications include detection of toxins, such as microcystin, or carcinogenic substances such as Cr(VI), which offers improved limits of detection as compared to spectrophotometry as well as sample throughput, which can reach 20 samples/min. [7]. [1] M. Liu and M. Franko, Crit. Rev. Anal. Chem. 44, 328-353 (2014). [2] T. Kitamori, M. Tokeshi, A. Hibara, and K. Sato, Anal. Chem. 76, 52A-60A (2004). [3] M. Lubej, U. Novak, M. Liu, M. Martelanc, M. Franko and I. Plazl, Lab Chip (2015) DOI:10.1039/c4lc01460j. [4] M. Valcárcel and B. Lendl. Trends Anal. Chem. 23, 527-534 (2004). [5] T. Radovanović, M. Liu, P. Likar, M. Klemenc and M. Franko, Int. J. Thermophys. (2014) DOI:10.1007/s10765-014-1699-9. [6] T. Radovanović, Dissertation, University of Nova Gorica (2016). [7] M. Franko, M. Liu, A. Boškin, A. Delneri, and M.A. Proskurnin, Anal. Sci. 32, 23-30 (2016).
Ključne besede: Spektrometrija TLM, mikrofluidni sistemi, biomarkerji, alergeni, pesticidi, acetilholinesteraza
Objavljeno v RUNG: 07.11.2016; Ogledov: 5552; Prenosov: 42
Celotno besedilo (42,25 MB)

Opis: This presentation provides theoretical backround for thermal lens spectrometry (TLS) and TLS microscopy (TLM) and describes the basic instrumentation for TLS and TLM measurements. Presented applications of TLS and TLM include detection in HPLC (carotenoids, bilirubin, biliverdin), FIA (alergens, Ag, Ag+, phytoplankton and cyanobacterial pigments, organophospate pesticides) and TLM detection in microfluidic systems (Cr(VI), microcystin, NGAL, study of diffusion proceses)
Ključne besede: Spekrometry TLS, TLM, HPLC, FIA, microfluidics, bilirubin, biliverdin, carotenoids, alergens, mikrocystin, pigments, organophosphate pesticides, NGAL, Ag, Cr(VI), diffusion
Objavljeno v RUNG: 16.09.2016; Ogledov: 5181; Prenosov: 3
Celotno besedilo (35,40 MB)

Opis: Biogenic amines (BAs) are organic amines present in meat, fish, dairy produce and wine due to the breakdown of amino acids, catalysed by microbial decarboxylases. BAs determination in food is important not only because of possible toxicological effects such as nausea, sweating and headache but also due to their possible role as indicators of food spoilage. Chromatographic methods are traditionally applied for determination of BAs in food [1], which usually require preliminary operations for sample pre-treatment that are laborious and difficult to automate. On the other hand, screening analytical systems provide simple, low cost and rapid analysis with the possibility of subjecting high number of samples to the screening system in a short time [2]. In this work we present a novel method for screening determination of BAs using a microfluidic system with the detection by highly sensitive thermal lens microscope (μFIA-TLM). Four biogenic amines (putrescine, cadaverine, histamine and tyramine) were subjected to enzymatic catalysis by transglutaminase, where ammonia was released as a product of acyl transfer reaction between the peptide bound glutamine (Gln) and the amino group of BAs. Ammonia was further transformed into indophenol blue by the Berthelot reaction. The coloured product was detected in batch (static) mode in a 100 μm sample cell or in μFIA (flowing) mode in a microchip with the same optical path length. The detection was performed on a TLM system applying a solid-state diode as an excitation source (660 nm). Organic solvents were tested for signal enhancement. For evaluation of the sensitivity and determination of LOD values (S/N = 3 basis), the NH4Cl standard solution was applied in Berthelot reaction with further detection on TLM system. The LODs for NH4+ in batch mode and in μFIA were 24 μg/L and 109 μg/L, respectively. Both LOD values are lower than the LOD achieved with conventional spectrophotometry (180 μg/L). When mixtures of the indophenol standard solutions and EtOH in the ratio of 1:1 were prepared the LOD in batch mode was improved to 3 μg/L, achieving 60-times improvement compared to spectrophotometry.
Ključne besede: Biogenic amines, Thermal lens microscopy, microfluidics, translgutaminase
Objavljeno v RUNG: 05.07.2016; Ogledov: 5118; Prenosov: 0
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