An ultrasensitive sandwich-type electrochemiluminescent biosensor based on carbonaceous based nanomaterials was fabricated for alpha-fetoprotein detection. Herein, the composite of fullerene, graphene oxide and chitosan with specific surface area, good water dispersibility, and excellent biocompatibility was first modified onto the electrode surface and then it was in situ electrochemical reduced to improve the conductivity. After the capturing antibody was immobilized onto the modified electrode surface, the detection antibody together with poly(amidoamine) dendrimers functionalized carbon nanodots as the recognizable signal tags was self-assembled onto the electrode by typical sandwich immune reaction. By this design, the abundant functional groups, good water dispersibility and good electroconductivity of poly(amidoamine) dendrimers functionalized carbon nanodots make the composite not only an immobilizing platform to carrier numerous detection antibodies, but also an promising promoter for the electrochemiluminescent signal of luminol. With the aforementioned amplify factor, the established electrochemiluminescent biosensor under the optimal conditions demonstrated a wider dynamic response from 1 fg mL (1) to 80 ng mL (1) with a low detection limit of 0.33 fg mL (1). Additionally, the experimental results exhibited the immunosensor possessed excellent stability, reproducibility and selectively. Accordingly, this immunosensing strategy for alpha-fetoprotein with the assistance of poly(amidoamine) dendrimers functionalized carbon nanodots provided a promising approach in clinical disease scanning. (C) 2016 Elsevier Ltd. All rights reserved.