A sensitive amperometric immunosensor based on dendrimer functionalized-graphene as nanocarrier for the detection of alpha-1-fetoprotein was developed. In this strategy, enzyme-labeled antibodies were combined with dendrimer functionalized-graphene. Enhanced sensitivity for the target was achieved by using a dual signal amplification strategy. Dendrimer functionalized-graphene as nanocarrier can load larger amounts of enzyme-labeled antibodies, which results in enhanced signals. Graphene can accelerate electron transfer and amplify signals due to its high electrical conductivity. Amperometric response by chronoamperometry was measured in PBS solution containing 1 mM hydroquinone and 2 mM H2O2. The proposed immunosensor was applied to detect alpha-1-fetoprotein in the range of 1.0-100 ng mL(-1) with a detection limit of 0.45 ng mL(-1). (C) 2014 Elsevier B.V. All rights reserved.