Living Cells Directly Growing on a DNA/Mn₃(PO₄)₂‐Immobilized and Vertically Aligned CNT Array as a Free‐Standing Hybrid Film for Highly Sensitive In Situ Detection of Released Superoxide Anions

Abstract

It is important to detect reactive oxygen species (ROS) in situ for investigation of various critical biological processes, and this is however very challenging because of the limited sensitivity or/and selectivity of existing methods that are mainly based on sensing ROS released by cells with short lifetimes and low concentrations in a culture medium. Here, a new approach is reported to directly grow living cells on DNA/Mn3(PO4)2‐immobilized and vertically aligned carbon nanotube (VACNT) array nanostructure as a smart free‐standing hybrid film, of which the DNA/Mn3(PO4)2 and VACNT provide high electroactivity and excellent electron transport, respectively, while the directly grown cell on the nanostructure offers short diffusion distance to reaction sites, thus constructing a highly sensitive in situ method for detection of cancer‐cell‐released ROS under drug stimulations. Compared to the measured ROS released by cells in a culture medium, the detection sensitivity with this constructed hybrid film increases by more than six times, which implies that ROS molecules (superoxide anions) secreted from living cells are immediately captured by this smart structure without diffusion process or with extremely short diffusion distance. This design considerably reduces the time from release to detection of the target molecules, minimizing the potential molecular decay due to the short lifetime or high reactivity.

Synthesis of Manganese Oxide Embedded Carbon Nanofibers as Effective Biomimetic Enzymes for Sensitive Detection of Superoxide Anions Released from Living Cells

“…The results in Figure B reveal that the presence of these interferents does not lead to obvious current response, even 10 times higher concentration of interfering species was added. The results verify that the sensor possesses excellent selectivity, which can be attributed to the specific catalytic activity of the biomimetic superoxide dismutase to O 2 •− …”

Effect of Carbon Nanotubes on Direct Electron Transfer and Electrocatalytic Activity of Immobilized Glucose Oxidase

“…A more positive redox potential is required to provide the driving force for the ET between the enzyme active center and the electrode for the oxidation biocatalysts, which contributes to cell voltage loss. Another area of intensive research is to use advanced smart carbon materials such as carbon nanotubes (CNTs), 18 − 21 carbon black, 22 , 23 carbon nanoparticles (NPs), 24 vertically aligned CNTs, 25 and graphene, 13 , 26 in immobilization and growth of enzymes/proteins and living cells for various biological processes and for electrochemical biosensors and biofuel cells. Among them, CNTs have attracted considerable attention for potential applications such as supporting materials for enzymes owing to their unique electrical conductivity, high chemical stability, biocompatibility, and large surface area.…”

DNA-induced synthesis of biomimetic enzyme for sensitive detection of superoxide anions released from live cell

“…The detection limit of the assay is calculated to be about 1.67 nM (S/N ¼ 3) with a sensitivity of 3.54 mA mM À1 , which is much more superior to most of previous reports. 14,23,[26][27][28] The response time of the electrode to O 2 c À is as short as 5 s, which is an advantage for the detection of O 2 c À due to its short lifetime. These results demonstrate that the present sensor may meet the requirement of O 2 c À detection in normal physiological conditions.…”