Reduced Graphene Oxide Based Electronic Sensors for Rapid and Label-Free Detection of CEA and CYFRA 21-1

Proper and early diagnosis of diseases is a key to efficient treatment and better prognosis. This paper reports a simple and label-free method of detection of two antigens – carcinoembryonic antigen (CEA) and cytokeratin-19 fragment (CYFRA 21-1) which are the biomarkers of many cancers including lung cancer. The sensor devices were fabricated by coating antibody/gold nanoparticles (AuNPs)/reduced graphene oxide (RGO) on indium tin oxide (ITO) coated glass. The sensors fabricated for detecting CEA had
$6 ~\mu \text{L}$
of CEA antibodies and the ones developed for detecting CYFRA 21-1 were coated with
$6 ~\mu \text{L}$
CYFRA 21-1 antibodies. The thickness of the graphene oxide was found to be ~1nm and the thickness of anti-CEA/AuNPs/RGO was found to be ~25 nm when observed using atomic force microscope. The sensing layers exhibited reflectance in the wavelength ranging from 248 to 300 nm when tested with UV-Visible spectrophotometer. A simple technique to capture the antibody-antigen binding has been developed in which the antigens are to be dropped onto the sensor devices and the change in the current across the sensors are to be measured. The biosensors were tested for 0.25 pg/mL to 20 ng/mL concentrations of CEA and CYFRA 21-1 at room temperature. The responses of the sensors ranged from 10.96 to 26.48% for 0.25 pg/mL to 20 ng/mL CEA and it varied from 17.66 to 26.68% for 0.25 pg/mL to 20 ng/mL CYFRA 21-1.