Electrochemical Determination of 8-Nitroguanine and 8-Hydroxy-2`-Deoxyguanosine in Urine and Whole Blood Using Stochastic Sensors

Three stochastic sensors based on reduced graphene oxide (reduced nanographene oxide, reduced graphene oxide decorated with TiO2 and nanoparticles of Au or Ag) paste modified with a complex of protoporphyrin IX with zinc, are reported for the electroanalysis of 8-nitroguanine and 8-hydroxy-2`-deoxyguanosine in whole blood and urine samples. The highest sensitivity for the assay of the biomarkers was recorded for the sensor based on reduced graphene oxide decorated with TiO2 and gold nanoparticles. Recoveries higher than 96.00% were recorded with relative standard deviation (%) values lower than 1.00% when the sensors were used for the determination of biomarkers in both urine and whole blood samples, demonstrating that the proposed stochastic sensors may be reliably applied for the molecular recognition and quantitative determination of the two biomarkers used in the diagnosis of leukemia and gastric cancer.