Immobilizing water-soluble graphene quantum dots with gold nanoparticles for a low potential electrochemiluminescence immunosensorElectronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04328j

Hydrazide-modified graphene quantum dots (HM-GQDs) obtained by refluxing GQDs with hydrazine hydrate were hybridized with gold nanoparticles (AuNPs) through a redox reaction between HM-GQDs and AuCl 4 − . The obtained nano-hybrids (HM-GQD-AuNPs) possess the unique electrochemiluminescence (ECL) properties of HM-GQDs and the easy self-assembly with some bio-molecules of AuNPs, which have great potential applications in bio-sensors. HM-GQD-AuNPs were modified on a glassy carbon electrode to develop a novel ECL immunosensor of carcinoembryonic antigen (CEA) as a model target analyte. Due to the increment of electron-transfer resistance after immunoreaction, the ECL intensity decreased as the concentration of CEA was increased. The linear response range was between 0.02 and 80 ng mL −1 , and the detection limit was 0.01 ng mL −1 . Nano-hybrids of hydrazide-modified graphene quantum dots (HM-GQDs)/gold nanoparticles (AuNPs) prepared from the redox reaction between HM-GQDs and AuCl 4 − were used for electrochemiluminescent immunosensor of carcinoembryonic antigen.