BACKGROUNDA sensitive nanostructured immunoelectrode based on poly(allylamine) (PAH) sandwich is developed for non-structural 1 (NS1) of dengue virus. NS1 is a secretory protein abundant in the acute phase of disease associated to hemorrhagic fever. Anti-NS1 antibodies are immobilized on the electrode surface by a thin layer of PAH assembled on carboxylated carbon nanotubes (CNTs). PAH is cationic polymer acting as bi-functional agent to tightly attach CNTs to the electrode surface and anti-NS1 antibodies through their Fc terminal, avoiding random immobilization. Electrochemical responses of immunoassay are generated at a controlled potential by a reaction between H2O2 and peroxidase enzyme conjugated to anti-NS1 antibodies. RESULTSThe immunosensor developed exhibited a linear range to NS1 varying between 0.1 mu g mL(-1) and 2.5 mu g mL(-1), with clinical range for early diagnostic of acute dengue and a limit of detection of 0.035 mu g mL(-1) that is much lower than the concentration observed from the first day after the onset of fever up to the 9th day. Serum samples are also tested showing good accuracy and specificity. CONCLUSIONSAn immunosensor for NS1 protein of dengue virus was developed. This versatile and reproducible PAH-sandwich platform can be applied to other immunoassays to give reliable and highly sensitive responses. (c) 2014 Society of Chemical Industry