Ultra selective label free electrochemical detection of cancer prognostic p53-antibody at DNA functionalized graphene

Detection of p53 antibody, a universal cancer biomarker, essential for the early diagnosis and prevention of cancer mortality. Here, we report label free electrochemical detection of p53 antibody binding with DNA on a graphene prepared by direct electrical exfoliation of pencil graphite in presence of aminoacid (glycine) in aqueous solution for the first time. Role of glycine in preventing graphitization is analysed using Fourier transform infrared spectroscopy, Raman, X-ray diffractommetry, X-ray photoelectron spectroscopy and transmission electron microscopy. Graphene has been decorated with gold nanoparticles prior to the biofunctionalization with DNA sequence, representing lung cancer, followed by its hybridization with a universal cancer biomarker anti-p53 antibody. Changes in the cyclic volatmetric and impedance signal of the graphene-gold modified electrode upon the occurrence of molecular binding events is monitored in the presence of ferri/ferro cyanide redox probe. The binding of DNA antibody has been theoretically confirmed using bioinformatic tool. Selectivity of the sensor is demonstrated using anti p21 antibody and DNA sequences from E-Coli pathogen. The cancer biomarker antibody can be detected in the concentration range from 0.1 ng/L to 0.1 mu g/L. The minimal concentration of dsDNA required for the efficient sensing of anti-p53 antibody is 0.6 fM. Both graphene preparation and cancer biomarker sensing methods are simple, rapid, easy to fabricate, stable and can be utilized for practical applications.