Real-time quantification of hydrogen peroxide production in living cells using NiCo2S4@CoS2 heterostructure

The real-time monitoring of hydrogen peroxide (H2O2) production in living cells is of paramount importance; however, the high complexity of biological fluids and low concentrations of in-vivo H2O2 are limiting the sensor's sensitivity and selectivity. Here, we described a carbon cloth (CC) modified nickel cobalt sulfide/cobalt sulfide nanostructured arrays (NiCo2S4@CoS2 NAs) as a highly sensitive and selective electrochemical transducer for tracking endogenous H2O2 production in real-time. A hydrothermal synthetical procedure was adopted to deposit the nanostructured arrays. NiCo2S4, an important class of binary transition metal dichalcogenide holds outstanding electrocatalytic activity thanks to its redox properties, enlarged electrocatalytic sites due to mixed valence states, and high conductivity. The growth of NiCo2S4 in association with cobalt disulfide CoS2 on a 3D conducting backbone leads to the nanostructured arrays. The structure, size of the particles, crystallinity, and composition of the arrays were analyzed by the state-of-the-art high-vacuum surface techniques. The NiCo2S4@CoS2 NAs@CC was found to have excellent electrocatalytic performance to reduce H2O2. The electrode displayed a rapid, sensitive, and durable amperometric sensing characteristics, over a linear range of 12.64 nM–2104 μM. The detection limit was 2 nM (S/N = 3). The sensor was able to quantify the amount of endogenously produced H2O2 released from Raw 264.7 cells. Thus, the binary TMDs based nanostructures have promising potential in live cell biosensing applications.