Low potential detection of NADH based on Fe3O4 nanoparticles/multiwalled carbon nanotubes composite: Fabrication of integrated dehydrogenase-based lactate biosensor

► GC electrode modified with multiwalled carbon nanotube and Fe3O4 nanoparticles. ► Fe3O4/MWCNTs nanocomposite shows well defined redox process at ca. −0.2 V. ► Redox system shows excellent electrocatalytic activity toward NADH oxidation.► With entrapment of alcohol dehydrogenase enzyme a stable lactate biosensor fabricated.► The proposed biosensor was used for detection of lactate in human serum samples.