Biosensor based on 3D graphene-supported Fe3O4 quantum dots as biomimetic enzyme for in situ detection of H2O2 released from living cells

Abstract

Real-time detection of hydrogen peroxide (H2O2) released from living cells has become important to study biological phenomena and oxidative stress-related diseases. However, selective detection and accurate in situ monitor of H2O2 in living cells is still a huge challenge because of its low concentration, large diffusivity and high reactivity. A biomimetic enzyme, ultrasmall Fe3O4 decorated on three-dimensional graphene nanocomposites (Fe3O4/3DG NCs), were prepared through in-situ growth of Fe3O4 quantum dots (QDs) with the size of 5–7nm on porous 3DG networks via a facile hydrothermal method, in which Fe3O4 QDs can possess intrinsic peroxidase-like activity to efficiently catalyze the electrochemical reduction of H2O2 while the highly porous 3DG networks offer large surface area and high conductivity. Electrochemical measurement results show that Fe3O4/3DG NCs exhibit excellent catalytic activity toward H2O2 with high selectivity and sensitivity (274.15mAM−1cm−2), low detection limit (∼78nM), fast response (2.8s) and outstanding reproducibility. This enzyme-free biosensor was further successfully used to in situ detect H2O2 released from living cells by controlling cell numbers and stimulation drug dose, showing significant potentially useful for us to understand the critical pathological process of cancer cells.