Electrochemical sensor of ultrarace L-cysteine in urine samples based on synergetic electrocatalytic effect of graphene oxide (GO) / manganese sulfide (MnS) nanohybrids

This paper reports a homogeneous post-precipitation strategy for in-situ depositing MnS nanoparticles onto the graphene oxide (GO) sheet surfaces to fabricate the GO/MnS nanohybrids for electrochemical sensing ultrarace L-cysteine in urine samples. The resulting GO/MnS nanohybrids exhibits high surface area, good site accessibility and excellent electrocatalytic activity for L-cysteine because of the synergistic effect of the graphene oxide (GO) and manganese sulfide (MnS) hetero-structures. In comparison with the MnS modified gold electrode, the oxidation peak current of L-cysteine at GO/MnS nanohybrids modified gold electrode is about 4.5-fold stronger, and the detection limit for L-cysteine is about 13.7-fold lower. An excellent electrochemical selectivity for Lcysteine over other interfering substances was also achieved. The method was successfully applied to the determination of L-cysteine in urine samples.