MXene Nanoconfinement\nof SAM-Modified Molecularly\nImprinted Electrochemical Biosensor for Point-of-Care Monitoring of\nCarcinoembryonic Antigen

The high rate of cancer worldwide and the heavy costs\nimposed on\ngovernments and humanity have always motivated researchers to develop\npoint-of-care (POC) biosensors for easy diagnosis and monitoring of\ncancer treatment. Herein, we report on a label-free impedimetric biosensor\nbased on Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene and imprinted ortho-phenylenediamine (o-PD) for the detection\nof carcinoembryonic antigen (CEA), a biomarker for various cancers\nsurveillance, especially colorectal cancer (CRC). Accordingly, MXene\nwas drop-casted on the surface of a disposable silver electrode to\nincrease the sensitivity and create high-energy nanoareas on the surface,\nwhich are usable for protein immobilization and detection. A self-assembled\nmonolayer (SAM) was exploited for oriented CEA immobilization on the\nMXene-modified electrode. The monomer-protein interaction and successful\nprotein removal were confirmed by molecular docking and atomic force\nmicroscopy (AFM) investigations to evaluate the quality of the fabricated\nmolecularly imprinted polymer (MIP). Also, the role of MXene in increasing\nthe electrical field inside the nanoareas was simulated using COMSOL\nMultiphysics software. A suitable limit of detection (9.41 ng/mL),\nan appropriate linear range of detection (10 to 100 ng/mL) in human\nserum, and a short detection time (10 min) resulted from the use of\nSAM/MIP next to MXene. This biosensor presented outstanding repeatability\n(97.60%) and reproducibility (98.61%). Moreover, acceptable accuracy\n(between 93.04 and 116.04%) in clinical serum samples was obtained\ncompared with immunoassay results, indicating the high potential of\nour biosensor for real sample analysis. This biomimetic and disposable\nsensor provides a cost-effective method for facile and POC monitoring\nof cancer patients during treatment.