Direct electrochemistry of cyt c and hydrogen peroxide biosensing on oleylamine- and citrate-stabilized gold nanostructures

•Two types of gold nanostructures: charge(citrate)-stabilized nanoparticles and sterically(OA)-stabilized nanoparticles and nanowires are assembled on electrodes.•Immobilization and electrochemical properties of the heme-containing metalloproteins cyt c and oxidoreductase enzyme HRP.•Nanostructured interfaces provide a good environment for stable and reproducible immobilization of electroactive proteins.•Enhancement of the electrochemical signal due to a greater electroactive surface area of the gold nanostructures.•The HRP sensor characteristics for biocatalytic reduction of H2O2 are improved compared to a thin-film HRP sensor by using gold nanostructures.