Highly sensitive electrochemical sensor based on environmentally friendly biomass-derived sulfur-doped graphene for cancer biomarker detection

Herein, we demonstrate a sulfur-doped reduced graphene oxide (SrGO) product fabricated using an eco-friendly biomass precursor “lenthionine” through a high temperature doping process. The product is used for making a highly sensitive electrochemical sensor for detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG) molecule, which is an important biomarker for oxidative stress, cardiovascular diseases, and cancers. The sulfur-doping amount was regulated and a maximum sulfur content of 2.28 atom% was achieved through controlling the precursor amount. Homogenous presence of large number of sulfur atoms in SrGO in the form of thiophenic (CSC) bond produced robust sensitivity (∼1 nM), very wide detection window (20-0.002 μM), good selectivity, high stability and reproducibility, and excellent recoveries for the detection of 8-OHdG biomarker in optimized experimental conditions. The excellent electrochemical sensitivity of SrGO sensor is attributed to the strong electron-donating ability of sulfur that facilitates the electron transfer to the biomolecules in the electrochemical reactions. Thus, the proposed method endorses an excellent platform for the electrochemical detection of 8-OHdG with great ease and reliability.