We reported Graphene Oxide/alpha-MnO2 binary nanosheets (GO/alpha-MnO2 BNSs) Based Non-Enzymatic Biosensor for the detection of guanine using selective and ultra-sensitive electrochemical method. In this work, GO/alpha-MnO2 BNSs synthesized using simple and cost-effective ultra-sonication method. As produced GO/alpha-MnO2 BNSs were investigated by FE-SEM, TEM, EDX, FT-IR, XRD, EIS and electrochemical methods. The electrochemical oxidation behavior of guanine at the GO/alpha-MnO2 BNSs modified electrode was evaluated by cyclic voltammetry (CV) while sensitive guanine detection was performed via Differential pulse voltammetry. The as-fabricated biosensor exhibited lower limit of detection was 23.9 (+/- 0.52) pM with excellent sensitivity about 8.835 (+/- 0.96) mu A mu M-1 cm(-2) (R-2 = 0.995) and linear range of 50 nM-10.5 mu M without surface fouling. The sensor was evidently examined for the detection of guanine in the real sample of DNA to predict unknown concentrations of guanine in the pH 5.0 phosphate buffer. (C) 2018 The Electrochemical Society.