NANOSTRUCTURED IRON OXIDE MODIFIED CONDUCTING PAPER FOR CANCER DIAGNOSTICS

Abstract

This dissertation contains results of the studies relating to the fabrication of a label-free, lightweight and flexible conducting paper based immunosensing platform comprising of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and iron oxide nanocomposite for the detection of carcinoembryonic antigen (CEA), a cancer biomarker. The effect of various solvents such as sorbitol, ethanol, propanol, n-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO) on the electrical conductivity of PEDOT:PSS coated whatman filter paper #1 (conducting paper, CP) has been investigated. Increment in the conductivity of the conducting paper electrode by two-fold was observed (from 6.84 x 10-4 to 2.40 x 10-2 S cm-1) after treatment with DMSO (DMSO@CP). Further, the incorporation of iron oxide nanoparticles (nFe2O3) into DMSO@CP has enhanced the electrochemical performance and signal stability. Thereafter, biorecognition element anti-CEA was immobilized on the modified electrode surface (nFe2O3/DMSO@CP) for the detection of CEA and bovine serum albumin (BSA) was used for blocking of nonspecific sites. Electrochemical response studies indicated that this BSA/anti-CEA/nFe2O3/DMSO@CP electrode has a sensitivity of 10.2 μA ng-1 mL cm-2, limit of detection 0.27 ng mL-1 with good linearity in the detection range 4-25 ng mL-1 and shelf life of 34 days. This fabricated immunosensor has also been validated via detection of CEA in serum samples of cancer patients employing ELISA technique.