Mitochondria-Targeted Near-Infrared Fluorescent Carbon Dots for Assessing ATP Levels in Cardiomyocytes under Exercise-Simulated Metabolic Stress

Abstract

Mitochondrial ATP homeostasis is fundamental to cardiac performance, particularly under exercise-induced metabolic stress. Herein, we report a mitochondria-targeted near-infrared fluorescent carbon dot nanoprobe (Mit-CDs) for in situ ATP imaging in cardiomyocytes. The Mit-CDs feature a graphitic core and a polyethyleneimine-functionalized surface enabling efficient mitochondrial localization and selective ATP recognition. The probe exhibits stable emission at 612 nm, high photostability, excellent biocompatibility, and a rapid, sensitive fluorescence response to ATP with a detection limit of 21.3 nM. In living AC16 cardiomyocytes, Mit-CDs allow real-time visualization of mitochondrial ATP fluctuations under exercise-simulated metabolic stress, and reliable ATP quantification in serum confirms their analytical robustness. This work provides a simple and effective in vitro nanosensing platform for investigating cardiac energy metabolism in exercise physiology.