Electrochemical deposition of Pd on MoS₂ supported graphene nanoflakes over functionalised MWCNTs as an immunosensor for detection of lung cancer biomarker

An electrochemical immunosensor was designed to quantify carcinoembryonic antigen (CEA), which is regarded as a tumour marker and prognostic indicator. The glassy carbon electrode (GCE) surface was modified using MoS2, graphene nanoflakes (GNs), fMWCNTs, and electrodeposited PdNPs for the first time to prepare a Pd- MoS2-GNs@fMWCNTs/GCE. The platform was activated with monoclonal anti-CEA. The prepared nano- composite material helps in improving the surface area and conductivity of the GCE. Moreover, PdNPs act as a linker between nanocomposite materials and anti-CEA, which enhances electron transport. The procedure used to analyse CEA involve sequential addition of CEA into the solution of 5 mM [Fe(CN)6]3-/4- prepared in 0.1 M PBS (pH 7.4) in the presence of fabricated electrode and DPV and EIS methods were used as detection technique. The change in signal response for the [Fe(CN)6]3-/4- redox reaction before and after CEA interaction is considered as the immunosensor response which is directly correlated with CEA concentration. Further, in DPV, the signal inhibition approach was used to measure CEA by monitoring the decrease in oxidation peak current of [Fe (CN)6]3-/4- due to the formation of CEA/anti-CEA immunocomplex. The electrochemical immunosensor demonstrated low LOD of 2 pg/mL and a correlation coefficient of 0.98 within a broad linear range of CEA concentration from 0.002 to 500 ng/mL. The fabricated immunosensor displayed excellent selectivity, repeat- ability, and stability. Further, the proposed immunosensor effectively measured CEA levels in human blood serum, making it an effective tool for testing CEA in clinical samples.