Carbon Nanohorns/Nafion/Fe3O4@Pd immunosensor for Shrimp Tropomyosin

A method for detecting an analyte in a food sample, the method comprising:

• fabricating an immunosensor by a method further comprising:
• preparing at least 0.1 mg/mL of an oxidized solution of carbon nanohorns by dispersing the carbon nanohorns in at least 0.1% of Nafion perfluorinated resin solution;
• synthesizing magnetic nanoparticles simultaneously by a method further comprising:
• mixing at least 4 mL of ultrapure water and at least 10 mM of ascorbic acid, preparing a mixture;
• adding at least 10 mM of K2PdCl6 to the mixture;
• adding at least 4 mL of 0.1% of Fe3O4 nanoparticles dispersed in ultrapure water;
• stirring the above solution at 700 rpm for t least 1 hour at a temperature of 60° C., followed by magnetic separation for at least 3 minutes and washing with ultrapure water, preparing the magnetic iron oxide-palladium nanoparticles;
• redispersing the magnetic nanoparticles in at least 2 mL of the ultrapure water;
• combining the oxidized solution of carbon nanohorns with the iron oxide-palladium nanoparticles, followed by stirring for at least 3 hours at 60° C., synthesizing a nanocomposite film;
• dropping at least 3 μL of the synthesized nanocomposite film onto a screen-printed electrode until completely drying, fabricating the immunosensor;
• loading at least 3 μL of the food sample onto the immunosensor, followed by incubating for at least 30 minutes, forming an immunocomplex between a binding agent on the immunosensor and the sample;
• washing the electrode with at least 10 m-M of Phosphate-buffered saline (PBS) buffer at pH 7.4, removing unreacted proteins from the sample;
• monitoring an electrical signal developed on the electrode;
• and
• detecting the analyte concentration.