Fabrication of hexahedral Au-Pd/graphene nanocomposites biosensor and its application in cancer cell H₂O₂ detection

Currently, real time monitoring of chemical substances in vivo and in vitro has gained enormous attraction, and many researches reports have been focused on the design and construction of high-performance biosensor devices. In this work, a high-performance sensor was constructed by taking advantage of the excellent electrochemical activity and high-index facets of Au-Pd nanocubes and the large surface of rGO. Glassy carbon electrodes (GCEs) were modified by both Au-Pd nanocubes and rGO nanocomposites via physical adsorption. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were utilized to characterize and identify this unique nanostructure. These three-dimensional nanocomposites possess a high electroactive surface area and an excellent electrical conductivity, which resulted in favorable electroreduction activity toward H₂O₂ with a lower detection limit of 4 nM, a wide linear range from 0.005 μM to 3.5 mM and a rapid response time. Furthermore, the proposed sensor exhibited desirable performance in the detection of endogenous H₂O₂ in human serum samples and real-time monitoring of H₂O₂ released from living breast cancer cell lines. In summary, this work not only provides a potential method to construct a physiological and pathological H₂O₂ biosensor but also makes a valuable contribution to the early diagnosis of different cancers.