Flexible electrochemical sensor based on N-doped helical carbon nanotubes coated manganese oxide nanoparticles for real-time monitoring of cellular hydrogen peroxide release

Electrochemical sensor is a sensitive and fast method to test hydrogen peroxide (H 2 O 2 ) released from cancer cells. To map a clear understanding of the mechanisms during drug treatment of cancer, it is necessary to in-situ and real-time monitor of H 2 O 2 content in the release process from cancer cells. Herein, N-doped helical carbon nanotubes (HCNTs) coated manganese oxide (MnO) nanoparticles (MnO@HCNTs) were prepared using a high-temperature molten salt method. The ratio of Mn salt to 2-methylimidazole was adjusted to optimize the Mn 2+ /Mn 3+ ratio of the active center. The MnO@HCNTs were further modified on a polydimethylsiloxane (PDMS) based electrode printed by screen printing technique to build a flexible electrochemical sensor (MnO@HCNTs/PDMS). The presence of graphitic N increases the surface electron density, thereby enhancing the electrical conductivity of MnO@HCNTs/PDMS. Simultaneously, graphitic N triggers electronic arrangement in the Mn, leading to an increase in Mn-N coordination. Furthermore, the adsorption performance of MnO@HCNTs/PDMS for H 2 O 2 increases with more N content, which may also enhance the electrocatalytic activity towards H 2 O 2 . The sensitivity of this sensor for H 2 O 2 analysis was observed as 636.9 μA μM −1 cm −2 with a limit of detection as 2.6 nmol L −1 in a linear response range from 10.0 nmol L −1 to 1000.0 nmol L −1 and a fast response time of 1.2 s. Finally, the flexible MnO@HCNTs/PDMS was combined with a smart sensing system, which displayed the ability for highly sensitive real-time monitoring of drug-stimulated H 2 O 2 that released from lung cancer cells A549 under the phorbol ester stimulation.