Impedimetric\nDetection of Calreticulin by a Disposable\nImmunosensor Modified with a Single-Walled Carbon Nanotube-Conducting\nPolymer Nanocomposite

Abstract

A label-free impedimetric immunosensing system was constructed\nfor ultrasensitive determination of the calreticulin (CALR) biological\nmarker in human serum samples utilizing an electrochemical impedance\nspectroscopy analysis technique for the first time. The new biosensor\nfabrication procedure consisted of electrodeposition of single-walled\ncarbon nanotubes (SWCNTs) incorporating polymerization of an oxiran-2-yl\nmethyl 3-(1H-pyrrol-1-yl) propanoate monomer (<i>Pepx</i>) onto a low-cost and disposable indium tin oxide (ITO) electrode.\nThe <i>SWCNTs-PPepx</i> nanocomposite layer was prepared\nonto the ITO after the one-step fabrication procedure. The fabrication\nprocedure of the immunosensor and the characteristic biomolecular\ninteractions between the anti-CALR and CALR were characterized by\nelectrochemical analysis and morphological monitoring techniques.\nUnder optimum conditions, the proposed biosensor was responsive to\nCALR concentrations over the detection ranges of 0.015–60 pg/mL\nlinearly, and it had a very low detection limit (4.6 fg/mL) and a\nfavorable sensitivity (0.43 kΩ pg^–1 mL cm^–2). The reliability of the biosensor system in clinical\nanalysis was investigated by successful quantification of CALR levels\nin human serum. Moreover, the repeatability and reproducibility results\nof the biosensor were evaluated by using Dixon, Grubbs, <i>T</i>-test, and <i>F</i>-tests. Consequently, the proposed biosensor\nwas a promising method for scientific, rapid, and successful analysis\nof CALR in human serum samples.