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Esteban-Fernandez De Avila B.,Complutense University of Madrid | Campuzano S.,Complutense University of Madrid | Pedrero M.,Complutense University of Madrid | Salvador J.-P.,Nanobiotechnology for Diagnostics Nb4D | And 4 more authors.
Analytical and Bioanalytical Chemistry

A novel strategy for the construction of a disposable integrated amperometric immunosensor for the sensitive and rapid determination of lipoprotein(a) (Lp(a)), an important predictor of cardiovascular disease risk, in human serum is reported. The approach uses a sandwich format involving the covalent immobilization of selective capture antibodies (antiLp(a)) on the surface of N-[N α,N α-bis(carboxymethyl)- lysine]-12-mercaptododecanamide (HS-NTA)-modified screen-printed carbon electrodes (SPCEs). After a blocking step with skimmed milk, the modified antiLp(a)-SPCEs were incubated with a mixture solution containing the target analyte and a fixed concentration of a specific biotinylated antibody (biotin-antiLp(a)) and a streptavidin-horseradish peroxidase (HRP) (Strep-HRP) conjugate. The amperometric responses of the resulting immunosensor at -0.10 V (vs an Ag pseudo-reference electrode), upon addition of 3,3′,5,5′- tetramethylbenzidine (TMB) as electron transfer mediator and H2O 2 as the enzyme substrate, were used to monitor the extent of the immunoreactions. The developed methodology exhibited a wide range of linearity between 0.02 and 10 μg mL-1, a low detection limit (LOD) of 8 ng mL-1, and a great selectivity against other serum components. The usefulness of the Lp(a) immunosensor was demonstrated by analyzing spiked serum samples as well as a reference serum containing a certified Lp(a) content. © 2014 Springer-Verlag Berlin Heidelberg. Source

Pastells C.,Nanobiotechnology for Diagnostics Nb4D | Pastells C.,CIBER ISCIII | Pascual N.,Nanobiotechnology for Diagnostics Nb4D | Pascual N.,CIBER ISCIII | And 4 more authors.
Analytical Chemistry

A novel immunochemical approach to diagnose Pseudomonas aeruginosa infections is reported, which is based on the quantification of relevant and specific virulence factors secreted by this microorganism. Specific antibodies have been raised using hapten PC1 (a 1:1 mixture of 9-hydroxy- and 6-hydroxy-phenazine-2-carobxylic acids), designed to recognize 1-hydroxyphenazine (1-OHphz), which is the main metabolite of pyocyanin (PYO). PYO is one of the most important virulence factors produced by nearly all P. aeruginosa strains, and other species do not produce this factor. With these antibodies, an immunochemical analytical procedure able to quantify both 1-OHphz and PYO in complex clinical samples has been developed. 1-OHphz can be directly measured in solubilized sputum samples diluted 20 times with the assay buffer. Quantification of PYO is accomplished after conversion to 1-OHphz in just 20 min under basic conditions. A LOD of 0.60 ± 0.01 nM (4.80 ± 0.08 nmol kg-1 sputum) is reached for both biomarker targets under the conditions established, a value that is much below the reported concentrations on sputum samples obtained from infected patients (up to 100 μM). The assay is robust, reproducible, accurate, can be run in about 2 h, and many samples can be measured simultaneously. The present reported assay could represent a significant improvement in the diagnosis of infectious diseases caused by this pathogen. © 2016 American Chemical Society. Source

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