Dynamic monitoring of Cytochrome c in single tumor cell for anticancer drug susceptibility assessment

Background

The release of Cytochrome c (Cyt c) from mitochondria into the cytosol is a key event in the intrinsic apoptosis pathway induced by chemotherapeutic agents. The dynamic monitoring of intracellular Cyt c levels is therefore of significant clinical importance for understanding tumor cell apoptosis.

Results

Herein, we developed a highly sensitive and selective nanoelectrochemical biosensor for the in situ monitoring of Cyt c dynamics in a single living cell. The sensor was constructed by modifying a Platinum nanoelectrode (PtNE) with a Cyt c-specific aptamer (Apt), denoted as PtNE/Apt. Employing Fast-scan voltammetry (FSV) at an ultra-high scan rate of 10 kV/s, the biosensor achieved a remarkable detection limit of ∼1.0 × 10^-13 mol/L for Cyt c. Using this platform, we performed real-time single-cell analysis, revealing that the intracellular concentration of Cyt c increased from undetectable levels to 1.8 μmol/L, while cell viability decreased from 99.9% to 45.1%, within 60 min of Cisplatin (CDDP) treatment. Furthermore, the platform enabled the evaluation of chemotherapeutic efficacy, ranking the susceptibility of HeLa cells to four drugs as follows: CDDP > Paclitaxel (PTX) > Doxorubicin (DOX) >Resveratrol (RSV).

Significance and Novelty

This aptamer-based nanoelectrochemical sensing strategy provides a powerful and high-precision tool for the dynamic analysis of apoptosis-related molecules, offering profound insights into the mechanisms of chemotherapeutic action and holding great potential for applications in individualized treatment screening.