Spiropyran-Based Fluorescent Anion Probe and Its Application for Urinary Pyrophosphate Detection

Abstract

In recent decades, numerous spiropyran derivatives have been designed and utilized for optical sensing of metal ions. However, there is still less research on spiropyran-based anion sensors. In this work, a new spiropyran compound (L) appended with a pendant bis(2-pyridylmethyl)amine was synthesized and used in fluorescent sensing of pyrophosphate ion (PP(i)) in aqueous solution. The molecular recognition and signal transduction are based on the cooperative ligation interactions and the ligation-induced structural conversion of the spiropyran, which leads to a significant change in the photophysical property of the spiropyran. In an ethanol/water solution (30:70, v/v) at pH 7.4, ligation of L with Zn(2+) causes an intense fluorescence emission at 620 nm at the expense of the original fluorescence at 560 nm. Once PP(i) was introduced, interaction between PP(i) and the L-Zn(2+) complex leads to full quenching of the 620 nm band emission which was concomitant with recovery of the 560 nm band emission, and the fluorescence intensity ratio, F(560)/F(620), is proportional to the PP(i) concentration. Under the optimum condition, the L-Zn(2+) complex responds to PP(i) over 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. The fluorescence response is highly selective for PP(i) over other biologically related substrates, especially the structurally similar anions, such as phosphate and adenosine triphosphate. The mechanism of interaction among L, Zn(2+), and PP(i) was primarily studied by (1)H NMR, (31)P NMR, and HRMS. To demonstrate the analytical application of this approach, the PP(i) concentration in human urine was determined. It was on the order of 3.18 x 10(-5) M, and the mean value for urinary PP(i) excretion by three healthy subjects was 62.4 micromol/24 h.

Evolution of Rhodamine B into Near‐Infrared Dye by Phototriggered Radical Reaction and Its Application for Lysosome‐Specific Live‐Cell Imaging

“…Photochromic reaction based on azobenzenes, [27] diarylethenes, [28] and spiropyranes [29] were fully explored. However, rhodamine-based photochromic reactions were rarely reported.…”

Aggregation-Induced Emission Active Metal-Free Chemosensing Platform for Highly Selective Turn-On Sensing and Bioimaging of Pyrophosphate Anion

“…[16][17] To circumvent this problem, in the recent years, certain metal complexes, mostly of Zn(II), Cd(II) or Cu(II), have been used for PPi sensing. [18][19][20][21][22][23] Such studies are based on the strong interaction of PPi with the metal-chemosensor ensemble, which in turn alters the coordination environment of the metal ion and triggers a measurable response. This kind of indirect anion sensing system is likely to compromise with the sensitivity of detection.…”

Tetraphenylethene based zinc complexes as fluorescent chemosensors for pyrophosphate sensing

“…Among the phosphates, adenosine triphosphate (ATP) and inorganic pyrophosphates (PPi) have been of particular interest [6,7], which are involved in energy transduction in organisms and control metabolic processes through participation in various enzymatic reactions [8,9]. In the past decades, a number of zinc-complex based fluorescent chemosensors for PPi sensing have been reported [10,11], including several classic ligands such as bis (2-pyridylmethyl) amine (DPA) [12,13], terpyridine (tpy) [14], and amide [15,16].…”