Ratiometric electrochemical aptasensor based on functionalized graphene nanocomposites for detection of CA19-9

A ratiometric electrochemical aptasensor was constructed based on rGO-cMWCNTs/AuNPs functionalized graphene nanocomposites for the detection of CA19-9 in serum samples. First, rGO-cMWCNTs/AuNPs nanocomposites were modified on the surface of glassy carbon electrodes. Second, the aptamer complementary chain labeled with anthraquinone-2-carboxylic acid (cDNA-AQ) was covalently linked by Au-S. Finally, the hybrid chain was formed with ferrocene (Fc)-labeled Apt-Fc by base pairing, and a sensing interface with specific target recognition and electrochemical signal amplification was constructed. In this study, the ratio of response signal to internal reference signal (I_Fc/I_AQ) was used as the target molecular response signal to achieve the quantitative detection of CA19-9. The ratiometric electrochemical biosensor based on aptamer molecular recognition has good selectivity, reproducibility and stability. Under the optimal reaction conditions, the logarithm of CA19-9 concentration had a good linear relationship with I_Fc/I_AQ, the linear range was 1.0-1.0 × 10⁶ mU/mL, the detection limit was 0.65 mU/mL, and the recovery rate in CA19-9 serum was 94.12-97.83%. The results show that the sensor has potential practical application prospects, and provides a simple and feasible strategy for the rapid and accurate detection of other tumor markers.