Simultaneous electrochemical detection of multiple tumor markers using functionalized graphene nanocomposites as non-enzymatic labels

In this work, we designed a novel sandwich-type electrochemical immunosensor for simultaneous detection of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) using non-enzymatic multiple-label method. Firstly, gold nanoparticles (AuNPs) decorated reduced graphene oxide (rGO)-carried prussian blue (PB) and AuNPs decorated rGO-carried thionine (Thi) (denoted as AuNPs-PB@rGO and AuNPs-Thi@rGO, respectively) were employed as distinguishable signal tags, which were utilized to load anti-CEA (Ab2,1) and anti-AFP (Ab2,2), respectively. Subsequently, hierarchically aloe-like gold microstructures (HAG) with large effective area were used to immobilize the capture antibodies anti-CEA (Ab1,1) and anti-AFP (Ab1,2), which effectively enhanced the performance of the immunosensor. Experimental results revealed that the sandwich-type immunosensor can permit the simultaneous detection of CEA and AFP with linear range of 0.6-80 ng mL−1 for two analytes, the detection limit was 0.12 ng mL−1 for CEA and 0.08 ng mL−1 for AFP (at a signal to noise ratio of 3), respectively. The immunosensor was applied to real sample analysis, and the recovery was within 95.9%-105.6% for CEA and 95.6%-105.4% for AFP. In addition, the immunosensor exhibited good reproducibility and stability, suggesting the immunosensor offered potential in analysis of biological samples.