Asymmetric Nanopore Electrode-Based Amplification for Electron Transfer Imaging in Live Cells

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Cell Biology

Background:

• Real-time monitoring of intracellular electron transfer, enzyme activity, and biochemical messengers is crucial for understanding cellular signaling.
• Existing methods for detecting redox-active species in living cells lack generalizability and compartment-specific resolution.
• Nanoelectrode fabrication for intracellular detection faces challenges in achieving high signal-to-noise ratios due to 3D fabrication complexities.

Purpose of the Study:

• To develop a generalizable method for characterizing a broad range of redox-active species within single living cells at the subcellular level.
• To report an asymmetric nanopore electrode-based amplification mechanism for real-time monitoring of nicotinamide adenine dinucleotide (NADH) in living cells.
• To enable sensitive and selective probing of trace redox-active species and evaluate cellular responses to stimuli like anticancer drugs.

Main Methods:

• A two-step 3D fabrication process was employed to create a modified asymmetric nanopore electrode with a diameter as small as 90 nm.
• The asymmetric geometry facilitates a significant potential drop, converting faradaic current to a distinguishable bubble-induced transient ionic current.
• Signal amplification of at least three orders of magnitude was achieved, enhancing current resolution from nanoamperes to picoamperes for wireless detection.

Main Results:

• The developed asymmetric nanopore electrode enables real-time detection of redox metabolism in living cells with high signal-to-noise ratio.
• The system achieves highly sensitive and selective probing of NADH concentrations down to 1 picomolar (pM).
• The electrode successfully monitored the respiration chain (NADH) in living cells and evaluated the effects of anticancer drugs in MCF-7 cells.

Conclusions:

• The integrated wireless asymmetric nanopore electrode offers a promising platform for sensitive, real-time intracellular analysis of redox-active species.
• This technology significantly advances the ability to study electron transfer dynamics and cellular communication in live cells.
• The method provides a foundation for future imaging of complex biochemical processes within cellular compartments.