Novel Near-Infrared Fluorescent Probe Sheds Light on Mitochondrial Health, Researchers Say


Researchers have developed a novel near-infrared fluorescent probe, FNIR-pH, that allows sensitive detection of mitochondrial pH and study of mitophagy, revealing cellular health and disease processes.

Scientists from Xuzhou Medical University and Yangtze Normal University in China have unveiled a groundbreaking discovery in the field of mitochondrial research (1). Their study, published in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, introduces a novel near-infrared fluorescent probe, FNIR-pH, designed to detect mitochondrial pH (1).

3d rendered Digital illustration of Mitochondria in colour background | Image Credit: © RAJCREATIONZS -

3d rendered Digital illustration of Mitochondria in colour background | Image Credit: © RAJCREATIONZS -

The mitochondria is one of the important parts of the cell. Being known as the powerhouse of the cell, the mitochondria performs several vital functions to keep the cell healthy (1). The importance of mitochondria to cellular health is a huge reason why it is important that there is a method that could detect dysfunctional mitochondria and abnormal pH levels within these organelles (1). If left untreated, these symptoms can lead to various destructive cellular processes, including mitophagy, cell apoptosis, and intercellular acidification (1). In this study, the research team synthesized the FNIR-pH probe to gain deeper insights into these mechanisms, utilizing the hemicyanine scaffold as a fluorophore (1).

For mitochondrial pH, the FNIR-pH probe is the substrate, and it exhibits fast fluorescence responses when exposed to basic solutions (1). The deprotonation of the hydroxy group in the probe's structure triggers a turn-on fluorescence effect, enabling precise monitoring of mitochondrial pH levels (1). Remarkably, the FNIR-pH probe demonstrated an approximately 100-fold increase in fluorescence intensity at a wavelength of 766 nm within the pH range of 3.0 to 10.0 (1).

The researchers also highlighted the probe's outstanding selectivity towards various metal ions, its excellent photostability, and its low cytotoxicity, which are crucial attributes for successful biological applications (1). With a pKa value of 7.2, the FNIR-pH probe enables real-time monitoring of mitochondrial pH changes in live cells and facilitates the sensitive detection of mitophagy, a critical cellular process involved in maintaining mitochondrial quality (1).

Furthermore, the team successfully implemented the FNIR-pH probe for fluorescent imaging in tumor-bearing mice, demonstrating its potential for in vivo imaging of bioanalytes and biomarkers (1). This breakthrough opens up further study of the mitochondria, and its role in cellular function. This study also reveals promising prospects for studying and diagnosing various diseases associated with mitochondrial dysfunction (1).

The FNIR-pH probe’s development is a significant technological advancement, and it helps contribute to a greater understanding of mitochondrial health and cellular processes (1). Its unique capabilities and versatility make it a valuable tool for researchers in the field of biological sciences, potentially leading to advancements in the diagnosis and treatment of mitochondrial-related disorders. It will be interesting to see how this probe could be used to bring about future discoveries and breakthroughs in cellular biology and medicine.


(1) Fang, M.; Zhou, X.; Wang, S.; Yang, Y.; Cheng, Y.; Wang, B.; Rong, X.; Zhang, X.; Xu, K.; Zhang, Y.; Zheng, S. A novel near-infrared fluorescent probe with hemicyanine scaffold for sensitive mitochondrial pH detection and mitophagy study. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2023, 298, 122791. DOI: 10.1016/j.saa.2023.122791

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