Graphene oxide reduced directly by redox probes for multiplexed detection of tumor markers.J Mater Chem B. 2014 Jun 07; 2(21):3292-3298.JM
Redox probe modified reduced graphene oxide was fabricated through directly reducing graphene oxide using redox probes (toluidine blue (TB) or amino-functionalized ferrocene (NH2-Fc)). Self-assembling gold nanoparticles to fabricate redox probe modified reduced graphene oxide-Au nanocomposites via electrostatic interaction was then carried out. A sandwich-type electrochemical immunosensor, for simultaneous multianalyte detection (carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) as model analytes), was designed. Redox probe modified reduced graphene oxide-Au nanocomposites are used as immunosensing probes and an ionic liquid functionalized reduced graphene oxide-Au (IL-rGO-Au) nanocomposite is used as an immunosensing substrate. The resulting immunosensor exhibited high selectivity and sensitivity during the simultaneous determination of CEA and AFP in a single run. The linear ranges were from 0.01 to 100 ng mL-1 for both CEA and AFP and the detection limits reached 0.003 ng mL-1 for CEA and 0.002 ng mL-1 for AFP. Importantly, the proposed immunosensor was evaluated for the analysis of clinical serum samples, producing a good correlation with the data determined by the ELISA. This indicates that the immunosensor provides a possible application for the simultaneous multianalyte determination of CEA and AFP in clinical diagnostics.