Ionic Liquid-Functionalized ZrO₂/Reduced Graphene Oxide Nanocomposites for Carcinoembryonic Antigen Electrochemical Detection

Herein, we develop an electrochemical immunosensor based on a zirconia-reduced graphene oxide-1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM.BF4) ionic liquid (ZrO2-rGO-IL) nanocomposite for the detection of a carcinoembryonic antigen (CEA) breast cancer biomarker. The characterization results of the synthesized ZrO2-rGO-IL nanocomposite show that it has high electroconductivity, oxygen functionalities, and a larger active surface area, which favors high loading of anti-CEA antibodies. The fabricated BSA/anti-CEA/ZrO2-rGO-IL/GCE immunosensor can detect CEA with high sensitivity and selectivity in a broad detection range between 25.0 fg mL–1 and 25.0 ng mL–1 with an ultralow limit of detection (LOD) of 1.23 fg mL–1 through differential pulse voltammetry (DPV). In addition, we tested the CEA in serum samples having linear detection ranges from 100.0 fg mL–1 to 5.0 ng mL–1 with an LOD of 2.25 fg mL–1. Subsequently, the incubation time and selectivity of the immunosensor show a great affinity for CEA. Therefore, the proposed immunosensor can be a promising candidate for CEA detection in clinical specimens. Prospectively, the synthesized nanocomposite will have the potential for the effective detection of other cancer biomarkers.