1,720,974 research outputs found
Multiparametric Oled-Based Biosensor for Rapid Dengue Serotype Recognition With a New Point-Of-Care Serological Test
No full textDevelopment of a point of care (POC) test as an immunobiosensor for okadaic acid detection in mussels
Full text linkThe increase in frequency and intensity of potential risks concerning the exposure of seafood to diarrhetic shellfish poisoning (DSP) toxins, even in areas not traditionally accomplished, raises the number of monitoring analyses for the detection of this class of toxins to guarantee the food safety of the products. In addition to the analysis performed with liquid chromatography-tandem mass spectrometry (LC-MS/MS), reference method in EU, semiquantitative rapid tests for preliminary screening and rapid monitoring plan are applied. Different kits for the detection of DTX family toxins are available on the market, but they require specialised labs and the cost of the analysis per sample is quite high. Based on the current situation, developing an easy-touse and cheap test for measuring okadaic acid, as the main responsible for DSP poisoning, for the implementation of point-of-care (POC) systems is desirable. An immunobiosensor test, based on immunoaffinity reaction utilizing commercially available monoclonal antibodies, has been optimized and validated for the detection of okadaic acid in mussel (Mytilus galloprovincialis) extracts, with a limit of detection of 60 mu g/kg, a sensitivity of 0.68 n degrees of counts/ ug/Kg and a screening test range between of 60-350 ug/kg. The proposed POC immunoassay provides results comparable (r = 0.981) to the ones obtained by other semiquantitative rapide tests, like enzymatic assay applied for routine monitoring plans for the detection of the dinophysistoxins (DTXs) family. The goal of the presented test is the reduction of steps for the toxin extraction and a relevant reduction of the time for the analysis and the provision of a cheap POC analysis system
Optimization of an OLED-based immunosensor for the detection of tetrodotoxin in mussels
No full textAlien species have colonized new aquatic ecosystems due to multifactorial effects, among which climate change or the increasing marine traffic, can be mentioned. The occurrence of contamination due to tetrodotoxin (TTX) is now observed in the Mediterranean Sea and in bivalves, whereas TTX was classically contaminating pufferfish in the Pacific Ocean. In this paper, we present the optimization of an Organic Light Emitting Diode (OLED) based immunosensor to detect tetrodotoxin in spiked samples of mussels. An ELISA test was preliminary optimized to set the concentrations of all biological elements required to develop the OLED-immunoaffinity-based biosensor and to mutually validate the two detection systems presently optimized. The threshold concentration of 44 ng g−1 set by EFSA for TTX in seafood products was used to distinguish the negative mussel samples from the positive ones. A streamlined extraction protocol was adopted after its optimization to fulfil the need of the assay (European Food Safety Authority, 2017)
A preliminary study on the degradation of AFB1 by Tenebrio molitor, Rhizopus oryzae and Trichoderma reesei
No full textRecently, genus Aspergillus, a fungus capable of producing aflatoxins, secondary highly toxic metabolites, has spread to new areas. These areas became suitable habitats due to the recent climate changes. The use of aflatoxin-contaminated crops is a cause of great concern in guaranteeing food safety and is responsible for major economic losses along the supply chain. For this reason, several strategies have been investigated to utilize these contaminated products as a possible food or feed resource by reducing or eliminating their aflatoxin content, but with limited relevant success. The presented study was aimed to evaluate a combination of biological processes to use aflatoxin B1 contaminated crops for their reintroduction into the production chain. The high tolerance to AFB1 and the apparent lack of accumulation in yellow mealworm larvae, reared on wheat bran substrates, spiked with increasing AFB1 concentration (0, 125, 250, 500 μg/kg) to obtain proteins of high biological value. Subsequently, the aflatoxin-degrading capacity of Rhizopus oryzae and Trichoderma reesei was applied to insect breeding waste (frass) in a fermentation process to ensure further utilization of biohazardous frass as soil conditioner. Individually, each process proven to be able to reduce the AFB1 present by about 80%, while the combination of the two approaches ensured the total degradation of aflatoxin B1-contaminated substrate and frass, which resulted in the possible production of biomass, that could be used for the feed and agricultural industry
Tailoring the chemical functionalization of a transparent polyethylene foil for its application in an OLED-based DNA biosensor
No full textFor the development of a bio-sensor based on fluorescence excitation in transmission, a plastic substrate with excellent optical characteristics, such as high optical transmission in the visible range and low self-fluorescence, is required. Polyethylene (PE) films have been found to meet these optical characteristics. However, the adhesion of short sequences of oligonucleotides used as bio-probes, which are needed to develop a genosensor, has not proven ideal on this substrate, due to its olefinic composition. In order to overcome this challenge, a physical-chemical surface modification of PE films has been performed using a corona treatment, followed by the attachment of functional organic compounds. The surface modified substrates have been characterized for their wettability, surface energy, zeta potential and surface topography. The bio-probes’ adhesion on the treated surfaces has been tested by monitoring the fluorescence of dye-conjugated complementary sequences of the oligonucleotides deposited on the modified PE substrates. Finally, two modified PE substrates, comprising the best adhesion of the bio-probes, have been used to prepare a genosensor for the detection of the DNA of the insect Hermetia illucens. As expected, the better adhesion of bio-probes on the functionalized PE substrate has allowed a significant improvement of the bio-sensor's limit of detection (LOD)
Chitin and its effects when included in aquafeed
Full text linkChitin, the second most abundant polysaccharide in nature after cellulose, has been the sub-
ject of increasing interest in recent years, particularly in the aquaculture sector. This review
focuses on the effects of chitin in aquafeed on growth, nutrient utilization, gut microbiome
modulation, and the immune system of aquatic organisms. Data from the literature showed
significant variability in response to chitin by species, with some species benefiting from
dietary chitin supplementation in terms of growth and immune health. However, excessive
chitin inclusion led to negative effects on the protein and lipid digestibility. These results
suggest that optimizing the amount of chitin-containing ingredients in aquafeed requires a
deep understanding of each species’ nutritional needs and other studies needed for differ-
ent aquaculture species. Furthermore, studies have highlighted the potential of chitin as an
immunostimulant and promoter of gut health. In conclusion, chitin appears to be a promis-
ing additive for sustainable aquaculture, but further research is needed to define best prac-
tices for its use
Effect of dietary chitin on growth performance, nutrient utilization, and metabolic response in rainbow trout (Oncorhynchus mykiss)
Full text linkThe dietary inclusion of ingredients containing chitin has been claimed to be beneficial to fish health. However, controversial results on growth performance and nutrient digestibility have been reported in literature. The present study aimed at assessing the response of rainbow trout (Oncorhynchus mykiss) fed with increasing levels of chitin (0, 1.5, 3.0, and 4.5 %) in a semi-purified basal diet. Protein and lipid digestibility was assessed and after 10 weeks of feeding, 6 h after the last meal, fish were euthanized for the evaluation of growth performance, blood biochemistry, brush border membrane and chitinolytic enzyme activity, gene expression of enzymes and nutrient transporters as well as the major pro-inflammatory intestinal cytokines, and mid intestine microbiota. Dietary chitin inclusion of up to 3 % did not hamper growth performances, nutrient apparent digestibility, and levels of most blood enzymes and metabolites. Diet including 4.5 % chitin negatively affected growth performances and nutrient digestibility. The application of a multidisciplinary approach highlighted that the biomarkers related to gut digestion functionality and inflammation response were altered also in fish fed the diets including 1.5 and 3 % of chitin, while gut microbiota did not differ between dietary treatments, even if some taxa suggested to be important in fish physiology were not recovered. Overall, the results demonstrate a good tolerance of rainbow trout to diets including chitin up to 3 %
Postprandial kinetics of digestive function in rainbow trout (Oncorhynchus mykiss ): genes expression, enzymatic activity and blood biochemistry as a practical tool for nutritional studies
Full text linkPostprandial kinetics of genes expression of gastric (chitinase, pepsinogen) and intestinal (alkaline phosphatase, maltase) digestive enzymes and nutrient transporters (peptide transporter 1, sodium-glucose transporter 1), Brush Border Membrane (BBM) enzymes activity (alkaline phosphatase, leucine aminopeptidase, maltase, saccharase) and blood biochemistry (triglycerides, cholesterol, protein, albumin, glucose, amino acids) through NMR spectroscopy, were investigated in rainbow trout (Oncorhynchus mykiss) fed a commercial aquafeed. For this purpose, fish were starved 72 h and digestive tract and blood were sampled before the meal and at 1.5, 3, 6, 9, 12, and 24 h after feeding (T0, T1.5, T3, T6, T9, T12 and T24). The postprandial kinetic showed that the expression of the genes involved in digestion and nutrient transport, the activity of BBM enzymes, and the presence of metabolites in blood were stimulated in different ways by the presence of feed in the digestive tract. The expression of most genes peaked 3 h after meal except gastric pepsinogen and maltase in distal intestine that peaked at T9 and T12, respectively. The activity of BBM enzymes were stimulated differently based on the intestine tract. The plasma proteins level increased from T1.5 until T9, while the other blood parameters unvariated during the postprandial period. This study supplied useful information about the physiological effects a single meal as a potential tool for planning nutritional studies involving the digestive functions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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