This invention relates to a photon fluorescent probe that visualizes pH. The photon fluorescent probe of this invention is based on a benzimidazole derivative structure and detects the pH of acidic regions and its changes. The probe has inherent isotropic emission, low toxicity, and high photostability, and can indicate color changes in photon fluorescence between pH 4-7, allowing for pH measurement in increments of 0.001 units. The photon fluorescent probe according to this invention selectively stains living cells and biological tissues internally while reacting with acidic pH to show a strong fluorescence color change (blue-green). Additionally, due to high solubility in water and low molecular weight, it can be easily loaded into cells. Furthermore, it can selectively detect pH in living cells over a period of 60 minutes or more and in biological tissues at depths of 100-200 μm, enabling the investigation of the distribution and activity of pH in living cells or intact biological tissues through ratio imaging. Therefore, it enables quantitative analysis of pH, comparison analysis of different samples, and can significantly contribute to life science research related to pH, early diagnosis of diseases, and the development of diagnostic reagents and treatments.
Benzimidazole-Based Ratiometric Two-Photon Fluorescent Probes for Acidic pH in Live Cells and Tissues
摘要:
Many aspects of cell metabolism are controlled by acidic pH. We report a new family of small molecule and ratiometric two photon (TP) probes derived from benzimidazole (BH1-3 and BH1L) for monitoring acidic pH values. These probes are characterized by a strong two-photon excited fluorescence, a marked blue-to-green emission color change in response to pH, pK(a) values ranging from 4.9 to 6.1, a distinctive isoemissive point, negligible cytotoxicity, and high photostability, thereby allowing quantitative analysis of acidic pH. Moreover, we show that BH1L optimized as a lysosomal-targeted probe allows for direct, real-time estimation of the pH values inside lysosomal compartments in live cells as well as in living mouse brain tissues through the use of two-photon microscopy. These findings demonstrate that these probes will find useful applications in biomedical research.