Fe₃C-Assisted Single Atomic Fe Sites for Sensitive Electrochemical Biosensing

Area of Science:

• Biomedical Engineering
• Materials Science
• Electrochemistry

Background:

• Detecting hydrogen peroxide (H₂O₂) from living cells is crucial for physiological and pathological studies.
• Single atomic site catalysts (SASCs) with peroxidase-like activity show potential for H₂O₂ detection but face challenges in structural modulation.
• Optimizing metal-support interactions is key to enhancing catalytic activity in SASCs.

Purpose of the Study:

• To develop a highly sensitive electrochemical biosensor for H₂O₂ detection.
• To investigate the synergistic effect of Fe₃C nanocrystals and single atomic Fe sites on H₂O₂ sensing performance.
• To demonstrate the practical application of the biosensor in monitoring H₂O₂ released from living cells.

Main Methods:

• Fabrication of a novel Fe₃C@C/Fe-N-C catalyst comprising single atomic Fe sites and carbon-encapsulated Fe₃C crystals.
• Electrochemical characterization of the proposed biosensor for H₂O₂ detection.
• Density functional theory (DFT) calculations to elucidate the electronic structure and catalytic mechanism.
• In vitro experiments to monitor H₂O₂ release from living cells.

Main Results:

• The Fe₃C@C/Fe-N-C biosensor exhibited superior peroxidase-like activity compared to conventional Fe SASCs (Fe-N-C).
• Achieved high sensitivity (1225 μA/mM·cm²), fast response (2 s), and a low detection limit (0.26 μM) for H₂O₂.
• Successfully demonstrated sensitive monitoring of H₂O₂ released from living cells.
• DFT calculations confirmed electron donation from Fe₃C to Fe sites, enhancing H₂O₂ activation.

Conclusions:

• The proposed Fe₃C@C/Fe-N-C material offers a synergistic enhancement of single atomic sites for electrochemical sensing.
• This work presents a new strategy for designing advanced catalysts for sensitive H₂O₂ detection.
• The developed biosensor holds promise for applications in physiological and pathological diagnostics.