Determination of the mycotoxin zearalenone in water by immunofluorescence and total internal reflection ellipsometry methods

In the scope of project Aquafluosense developing prototypes of fluorescence-based instrumentation for in situ measurement of several characteristic parameters of water quality, an immunofluorescent method have been developed for the detection of several environmental xenobiotics, including mycotoxin zearalenone (ZON). ZON, produced by several plant pathogenic Fusarium species, has recently been identified as an emerging pollutant in surface water, presenting a hazard to aquatic ecosystems. Due to its physico-chemical properties, detection of ZON at low concentration in surface water is a challenging task. The 96-well microplate-based fluorescent instrument is capable to detect ZON in the concentration range of 0.4–400 ng mL-1 . The sensitivity and accuracy of the analytical methods has been demonstrated by comparative assessment with detection by total internal reflection ellipsometry

Total Antioxidant Capacity and Total Phenolics Content of Phyllostachys Taxa Shoots

Total phenolic content (TP) and total antioxidant capacity (AC) were analysed in shoots of Phyllostachys aureosulcata (PA), P. aureosulcata f. aureocaulis (PAA), P. aureosulcata f. spectabilis (PAS), P. bissetii (PB), P. flexuosa (PF), P. humilis (PH), P. iridescens (PI), P. nigra var. nigra (PNN), P. nigra var. henonis (PNH), P. mannii (PM), P. sulphurea var. sulphurea (PSS), P. violascens (PVI), P. viridiglaucescens (PVG), P. vivax f. aureocaulis (PVA), collected on four harvest dates. Both TP and AC were determined following three processing methods, fresh, boiled and pickled in shoots of PF. Comparative study of TP and AC in the above Phyllostachys species shoots has not been reported before. The highest TP (1,227.6 μg GA/ml) and AC (154.0 μg AA/ml) values were measured in fresh shoots and the lowest in pickled ones. The highest values of TP were measured in the case of PA (1,321.95 μg GA/ml). The other taxa followed in decreasing order: PF, PVI, PI, PAA, PB, PAS, PNN, PNH, PM, PH, PSS and PVA. The highest AC values were obtained in the case of PI (184.24 μg AA/ml). The other taxa followed in decreasing order: PA, PF, PSS, PNN, PNH, PVG, PB, PAA, PAS, PV, PVA, PM and PH. The highest TP values were measured in taxa harvested on the first collection date and the values consequently decreased in taxa collected at later harvest dates. Our findings suggest that the earlier harvest date, through the influence of lower temperatures, could enhance the phytochemical content of bamboo shoots

Chlorophyll fluorescence instrumentation for a rapid, in situ measurement of algal density

In the project reported, we are developing an instrument for measuring algal density based on the detection of chlorophyll fluorescence. Following the adjustment of several parameters defined during preliminary analyses, measurements were made on different concentrations of model green and blue algal cultures. Fluorescent signal intensities measured by the prototypes of the fluorometer module were compared to values determined by other, widely used methods for estimation of algal density (i.e. Bürker chamber cell counting, optical density measurement and chlorophyll-a measurement with ethanol extraction method). Fluorometer results correlated well with the other methods, resulting high correlation coefficients (R2>0.9%). Limits of detection and limits of quantification showed a decreasing trend during the development phases resulting in a highly sensitive instrument

Antimicrobial Silver-Polyethyleneimine-Polylactic Acid Polymer Composite Film for Coating Methacrylate-Based Denture Surfaces

To prepare an antimicrobial polymer composite composed of silver- (Ag-) polyethyleneimine- (PEI-) polylactic acid (PLA) in chloroform, for coating the mucosal surfaces of methacrylate-based dentures as a prospective therapy for denture stomatitis. The water-insoluble, tightly bound, hard, micrometre-thin, and colourless film exerts its effects by direct contact with the pathogens and via the active constituents (Ag, PEI, and Ag-PEI) released slowly into the mucosa’s salivary layer. Silver and PEI were blended at 140°C, then bound to PLA. The Ag-PEI complex was characterised by dynamic light scattering and transmission electron microscopy, and the Ag-PEI-PLA composite was examined by atomic force microscopy and micro-computed tomography. The characteristic was measured by atomic force microscopy (AFM) and micro-computed tomography (micro-CT). The quantity of water-soluble Ag-PEI complex released from the composite film was measured with gravimetry. The cellular physiological effects were analysed by impedimetry and computer-based morphometry using human gingival epithelial cells. A real-time cell proliferation assay revealed moderate toxic effects of Ag-PEI on the epithelium. The viscous Ag-PEI-PLA solution produced could be applied as a thin film on methacrylate surfaces. Active antimicrobial components (Ag, PEI, and Ag-PEI) were released from the hard, tightly bound Ag-PEI-PLA coating. This study’s findings verified the applicability of the antimicrobial Ag-PEI-PLA composite for coating the inner surfaces of acrylate dentures. Owing to the well-known antimicrobial effects of silver and PEI and the supplementary effects of chloroform, this composite provides a new therapeutic method for denture stomatitis that can be easily performed by dentists

Enzyme-linked fluorescent immunoassay for monitoring the herbicide active ingredient glyphosate in water

Within a modular water quality assessment fluorimeter instrument family, a newly developed enzyme-linked fluorescent immunoassay has been utilized for the quantitative analytical measurement of the herbicide active ingredient glyphosate in surface water. The developed 96- well microplate-based competitive immunoassay with fluorescence detection provides a 2.5- fold lower limit of detection (LOD = 0.09 ng/mL) in the investigated concentration range of glyphosate (0–100 ng/mL) compared to the detection of visual absorbance signals. Additionally, fluorescence detection resulted in a wider dynamic range for glyphosate measurement. Matrix effect was not observed for the undiluted surface water samples, and cross-reaction was not detected between glyphosate and its main metabolite (Naminomethylphosphonic acid) and structurally similar compounds. The method allows rapid monitoring of glyphosate as a ubiquitous water contaminant of agricultural origin that can affect, due to its global use, both aquatic and terrestrial ecosystems

Application of an induced fluorometry-based method in algal growth inhibition tests

Aquatic ecosystems are strongly exposed to various micropollutants from agricultural origin. The harmful effect can be expressed directly on aquatic organisms and indirectly through the food chain. The use of ecotoxicity assays mainly in aquatic environments, and corresponding water quality assessment are undoubtedly important. Project Aquafluosense was designed to develop instrument prototypes of a fluorescence-based setup for in situ measurement of algal biomass and for application of flurescence in ecotoxicity assays. Fluorescence-based determination of algal density was validated by conventional methods and signals obtained by the fluorometer correlated well with the conventional methods for algal density determination. The applicability of the fluorometer developed was demonstrated in ecotoxicity assays using the herbicide active ingredient isoxaflutole in neat and formulated forms

Termikus effektusok vizsgálata akusztooptikai eszközökben = Investigation of thermal effects in acusto-optical devices

Kutatási projektünk során különböző típusú és rendeltetésű akusztooptikai eszközökben kialakuló termikus jelenségeket vizsgáltuk. Kidolgoztuk az akusztooptikai effektus termikus modelljét, amelyben az akusztikus nyaláb elnyelődése, valamint az ultrahangkeltő elektromos és akusztikus veszteségei következtében felszabaduló hőmennyiség-eloszlást, az ennek megfelelő hőmérséklet-eloszlást szimuláltuk. A modellt akusztooptikai hatásfok-mérésekkel, valamint működő cellán végzett termovíziós mérésekkel fejlesztettük és ellenőriztük. A számolt és mért hőmérséklet-eloszlás segítségével kiszámoltuk az akusztooptikai kristályok optikai és akusztooptikai paramétereinek termikus változását, és ezeket integráltuk a fény hangoszlopon bekövetkező diffrakcióját és terjedését leíró modellünkbe. Megállapítottuk, hogy az üzemi hőmérsékleten kialakuló termikus lencse jelentősen befolyásolhatja a fénynyaláb terjedési irányát és intenzitás-eloszlását. Eljárásokat dolgoztunk ki az ultrahangkeltő veszteségeink csökkentésére a technológia javításával. Optimalizáltuk az akusztooptikai eszközök dobozolását hőtechnikai szempontból, és a nagyobb akusztikus teljesítményen működő eszközöket kiegészítettük egy kétkörös aktív hőelvezető és hűtőelemmel. A bevezetett módszerekkel sikerült az eszközök hőmérsékletnövekedését nagyobb elektromos teljesítmény esetén is korlátozni, valamint a hőmérséklet-eloszlás frekvenciafüggését és gradiensét a kristályban csökkenteni. | We examined theoretically and practically thermal effects in different type acousto-optic devices designed for different purposes. We elaborated a numerical model of the thermal processes appearing in these devices. In this model we calculate the heat distribution arising from the absorption of acoustic waves and electric transducer losses and calculate the corresponding temperature distribution across the device. The development of the model has been supported by continuous measurement of the acousto-optic interaction efficiency and temperature distribution on the acousto-optic crystal surfaces. Starting from the measured and calculated temperature distribution in the crystal we simulated the thermal changes of its photoelastic and optical parameters. We included the results in our model, which simulates the propagation of the optical beams through the acousto-optic crystal, and found that the thermal lens effect considerably influences their propagation direction and transversal intensity distribution. Based on the thermal imaging measurements we improved our acousto-optic transducer technology to reduce its losses. We optimized the housing of the devices to effectively remove the heat from the crystal walls and elaborated an active cooling system capable to control device temperature during operation. These improvements helped to limit and stabilize temperature increase and temperature gradients even at higher input electric power levels

Development of an immunofluorescence assay module for determination of the mycotoxin zearalenone in water

Project Aquafluosense is designed to develop prototypes for a fluorescence-based instrumentation setup for in situ measurements of several characteristic parameters of water quality. In the scope of the project an enzyme-linked fluorescent immunoassay (ELFIA) method has been developed for the detection of several environmental xenobiotics, including mycotoxin zearalenone (ZON). ZON, produced by several plant pathogenic Fusarium species, has recently been identified as an emerging pollutant in surface water, presenting a hazard to aquatic ecosystems. Due to its physico-chemical properties, detection of ZON at low concentrations in surface water is a challenging task. The 96-well microplate-based fluorescence instrument is capable of detecting ZON in the concentration range of 0.09–400 ng/mL. The sensitivity and accuracy of the analytical method has been demonstrated by a comparative assessment with detection by high-performance liquid chromatography and by total internal reflection ellipsometry. The limit of detection of the method, 0.09 ng/mL, falls in the low range compared to the other reported immunoassays, but the main advantage of this ELFIA method is its efficacy in combined in situ applications for determination of various important water quality parameters detectable by induced fluorimerty—e.g., total organic carbon content, algal density or the level of other organic micropollutants detectable by immunofluorimetry. In addition, the immunofluorescence module can readily be expanded to other target analytes if proper antibodies are available for detection