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In this study, a paper-based microfluidic enzyme-linked immunosorbent assay (ELISA) was developed as a screening system for rapid detection of clenbuterol, which is illegally used as a growth promoter for food-producing animals. The microfluidic paper-based analytical device (μPAD) was combined with ELISA and the intrinsic properties of paper allowed the entrapment of antibody through cellulosic fibres, validating to be an alternative to 96-well ELISA microplate for food safety monitoring. Detection of clenbuterol in milk was achieved by measuring the intensity of colour change that was proportional to the analyte concentration with a detection limit of 0.2 ppb. The μPAD effectively reduces the cost, volume of reagents, and time required to run ELISA for food sample testing. usc Refereed/Peer-reviewed

In Portugal, the potent paralytic shellfish toxins (PSTs) have appeared irregularly since the onset of a national monitoring program for marine biotoxins in 1986. In years where high contamination levels were attained in bivalves, sporadic cases of human poisonings have been recorded, as in 1994 and 2007. The reappearance of high contamination levels led to the appearance of new cases during the autumn of 2018. This study details toxin ingestion, symptomatology and toxin elimination and metabolization in the fluids of two patients, who ingested mussels from the Portuguese southwest coast and required hospitalization due to the severity of symptoms. Toxin elimination was confirmed by ELISA in plasma and urine samples. In mussel samples, the toxin profile obtained by HPLC-FLD displayed a wide diversity of toxins, typical of Gymnodinum catenatum ingestion. However, in the urine samples, the toxin profile was reduced to B1 and dcSTX. Abundant compounds in mussels having an O-sulphate at C11, such as C1+2 and dcGTX2+3, were absent in urine. In plasma, PSTs were not detected by HPLC-FLD. Calculated toxin ingestion, resulting from consumption of an estimated 200-g portion, was in the range of 104–120 μg STX eq./kg b. w., Graphical abstract Image 1, Highlights • Since 1986 Gymnodinium catenatum contaminates irregularly bivalves in Portugal with PSTs. • Acute neurological symptomology, such as paraesthesias, has often required hospitalization. • During an episode in October 2018, toxins in fluids of two victims and toxin ingestion were studied. • Preliminary confirmation was done by ELISA in serum and urine. • PSP toxins with an O-sulphate at C11, abundant in mussels, were absent in urine.

Using ovalbumin as a model protein in pure solution it was found that affinity chromatography of antisera against either native ovalbumin (NOA) or heat‐denatured ovalbumin (HDOA) gave four different antibody populations AC1 4 from each antiserum, with different binding properties to the related or unrelated antigen. Direct ELISA was shown to be useless for differentiating NOA from HDOA. Immunoprecipitation in solution is time consuming and, moreover, whereas NAC1 was shown to be specific for NOA compared with HDOA, DAC1, NAC2 and DAC2 were shown not to be fully specific for HDOA. In contrast, by using as capture antibodies either NAC3 or DAC4, a sandwich ELISA can be designed which is fully specific for NOA or HDOA, respectively. An approach to the identification of the temperature at which ovalbumin has been heated is described. This test will show whether ovalbumin has been heated to lower than 65°C or higher than 85°C. The test was applied to juices from canned mushrooms containing 2% ovalbumin.

Electrospun polyhydroxybutyrate (PHB) fibers were dip-coated by polymethyl methacrylate-co-methacrylic acid, poly(MMA-co-MAA), which was synthesized in different molar ratios of the monomers via free-radical polymerization. Fabricated platfrom was employed for immobilization of the dengue antibody and subsequent detection of dengue enveloped virus in enzyme-linked immunosorbent assay (ELISA). There is a major advantage for combination of electrospun fibers and copolymers. Fiber structre of electrospun PHB provides large specific surface area available for biomolecular interaction. In addition, polymer coated parts of the platform inherited the premanent presence of surface carboxyl (-COOH) groups from MAA segments of the copolymer which can be effectively used for covalent and physical protein immobilization. By tuning the concentration of MAA monomers in polymerization reaction the concentration of surface -COOH groups can be carefully controlled. Therefore two different techniques have been used for immobilization of the dengue antibody aimed for dengue detection: physical attachment of dengue antibodies to the surface and covalent immobilization of antibodies through carbodiimide chemistry. In that perspective, several different characterization techniques were employed to investigate the new polymeric fiber platform such as scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA) measurement and UV-vis titration. Regardless of the immobilization techniques, substantially higher signal intensity was recorded from developed platform in comparison to the conventional ELISA assay.

Control of human African trypanosomiasis (HAT) in the Democratic Republic of Congo is based on mass population screening by mobile teams; a costly and labor-intensive approach. We hypothesized that blood samples collected on filter paper by village health workers and processed in a central laboratory might be a cost-effective alternative. We estimated sensitivity and specificity of micro-card agglutination test for trypanosomiasis (micro-CATT) and enzyme-linked immunosorbent assay (ELISA)/T.b. gambiense on filter paper samples compared with parasitology-based case classification and used the results in a Monte Carlo simulation of a lot quality assurance sampling (LQAS) approach. Micro-CATT and ELISA/T.b. gambiense showed acceptable sensitivity (92.7% [95% CI 87.4-98.0%] and 82.2% [95% CI 75.3-90.4%]) and very high specificity (99.4% [95% CI 99.0-99.9%] and 99.8% [95% CI 99.5-100%]), respectively. Conditional on high sample size per lot (> or = 60%), both tests could reliably distinguish a 2% from a zero prevalence at village level. Alternatively, these tests could be used to identify individual HAT suspects for subsequent confirmation.