A solution processed carbon nanotube modified conducting paper sensor for cancer detection

Abstract

A solution processed poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)–carbon nanotube (CNT) nano-composite has been utilized for the fabrication of a conducting paper (CP) via dip coating. Further, high conductivity of this paper (from ∼6.5 × 10⁻⁴ to 2.2 × 10⁻² S cm⁻¹) obtained by treating it with formic acid (CNT/FA@CP) is due to the removal of the non-conducting PSS molecules from its surface. This smart conducting platform has been used for the conjugation of the anti-carcinoembronic antigen (CEA) protein for quantitative estimation of CEA, a cancer biomarker. Transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and amperometric techniques have been used to characterize the low cost, flexible and environmentally friendly conducting BSA/anti-CEA/CNT/FA@CP) paper electrode that is found to be highly sensitive (7.8 μA ng⁻¹ ml cm⁻²) in the physiological range (2–15 ng ml⁻¹) of CEA. The response of the paper electrode is validated using CEA concentration of serum samples of cancer patients obtained via the immunoassay technique.