A homemade gold electrode is modified with a carbon nanotubes/gold nanoparticles nanocomposite to perform selective and sensitive electrochemical detection of dengue toxin. This nanostructured composite offers a large specific surface and a reactive interface allowing the immobilization of biological material. Dengue antibodies are immobilized on gold nanoparticles via covalent bonding for dengue toxin detection. The porous tridimensional network of carbon nanotubes and gold nanoparticles enhances the electrochemical signal and the overall performance of the sensor. After optimization, the system exhibits a high sensitivity of - 0.44 ± 0.01 μA per decade with wide linear range between 1 × 10-12 and 1 × 10-6 g/mL at a working potential of 0.22 V vs Ag/AgCl. The extremely low detection limit (3 × 10-13 g/mL) ranks this immunosensor as one of the most efficient reported in the literature for the detection of recombinant viral dengue virus 2 NS1. This biosensor also offers good selectivity, characterized by a low response to various non-specific targets and assays in human serum. The outstanding performances and the reproducibility of the system place the biosensor developed among the best candidates for future medical applications and for early diagnosis of dengue fever. Graphical abstract.
Keywords: Carbon nanotube; Dengue toxin; Differential pulste voltammetry; Electrochemical biosensor; Gold nanoparticles.