Spiropyran-based fluorescent anion probe and its application for urinary pyrophosphate detection

Area of Science:

• Analytical Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Spiropyran derivatives are widely used for optical sensing of metal ions.
• Research on spiropyran-based anion sensors remains limited.
• Developing selective sensors for pyrophosphate ions (PP(i)) is crucial for biological and medical applications.

Purpose of the Study:

• To synthesize a novel spiropyran compound (L) for fluorescent sensing of pyrophosphate ions (PP(i)).
• To investigate the molecular recognition mechanism and signal transduction pathway.
• To establish a selective and sensitive method for PP(i) detection in aqueous solutions and biological samples.

Main Methods:

• Synthesis of a new spiropyran derivative (L) appended with bis(2-pyridylmethyl)amine.
• Fluorescent spectroscopy for detecting PP(i) in ethanol/water solutions at pH 7.4.
• Utilizing Zn(2+) complexation to induce a ratiometric fluorescence response.
• Mechanism elucidation using (1)H NMR, (31)P NMR, and HRMS.
• Determination of PP(i) concentration in human urine samples.

Main Results:

• The synthesized spiropyran (L) forms a Zn(2+) complex exhibiting fluorescence emission at 620 nm.
• Introduction of PP(i) to the L-Zn(2+) complex results in fluorescence quenching at 620 nm and recovery at 560 nm.
• A ratiometric fluorescence intensity (F(560)/F(620)) proportional to PP(i) concentration was observed.
• The sensor demonstrated a dynamic range of 1.0 x 10(-6) to 5.0 x 10(-4) M with a detection limit of 4.0 x 10(-7) M.
• High selectivity for PP(i) over other biologically relevant anions was achieved.
• PP(i) concentration in human urine was successfully determined, with a mean excretion value of 62.4 micromol/24 h.

Conclusions:

• The developed spiropyran-based sensor provides a sensitive and selective method for fluorescent detection of PP(i).
• The cooperative ligation and structural conversion mechanism enables ratiometric signal transduction.
• The sensor's applicability in analyzing PP(i) in human urine demonstrates its potential for real-world applications.