Chemosensing of Guanosine Triphosphate Based on a Fluorescent Dinuclear Zn(II)-Dipicolylamine Complex in Water

Abstract

Guanosine triphosphate (GTP) is a key biomarker of multiple cellular processes and human diseases. The new fluorescent dinuclear complex [Zn 2 (L)(S)][OTf] 4 , 1 (asymmetric ligand, L = 5,8-Bis{[bis(2-pyridylmethyl)amino] methyl}quinoline, S = solvent, and OTf = triflate anion) was synthesized and studied in-depth as a chemosensor for nucleoside polyphosphates and inorganic anions in pure water. Additions at neutral pH of nucleoside triphosphates, guanosine diphosphate, guanosine monophosphate, and pyrophosphate (PPi) to 1 quench its blue emission (λ em = 410 nm) with a pronounced selectivity toward GTP over other anions, including adenosine triphosphate (ATP), uridine triphosphate (UTP), and cytidine triphosphate (CTP). The efficient quenching response by the addition of GTP was observed in the presence of coexisting species in blood plasma and urine with a detection limit of 9.2 μmol L −1 . GTP also shows much tighter binding to the receptor 1 on a submicromolar level. On the basis of multiple spectroscopic tools ( 1 H, 31 P NMR, UV−vis, and fluorescence) and DFT calculations, the binding mode is proposed through three-point recognition involving the simultaneous coordination of the N 7 atom of the guanosine motif and two phosphate groups to the two Zn(II) atoms. Spectroscopic studies, MS-ESI, and DFT suggested that GTP bound to 1 in 1:1 and 2:2 models with high overall binding constants of log β 1 (1:1) = 6.05 ± 0.01 and log β 2 = 10.91 ± 0.03, respectively. The optical change and selectivity are attributed to the efficient binding of GTP to 1 by the combination of a strong electrostatic contribution and synergic effects of coordination bonds. Such GTP selectivity of an asymmetric metal-based receptor in water is still rare.

Molecular Probes, Chemosensors, and Nanosensors for Optical Detection of Biorelevant Molecules and Ions in Aqueous Media and Biofluids

“…In this respect, the recently published work by Dorazco-González and coworkers reported an important advance in the field by introducing dinuclear Zn II -dipicolylamine (Zn II -dpa) complexes that can be used for the selective detection of GTP at μM concentrations in 40 mM MOPS buffer, pH 7.0, and artificial biological fluids ( C6.13 in Figure ). Although some Zn II –dpa complexes have been reported for the detection of phosphates and AMP, , the rationally designed asymmetric Zn II –dpa complex C6.13 allowed for selective GTP binding over other nucleosides in water and artificial biological fluids. Addition of GTP to C6.13 resulted in a strong binding ( K a = 10 6 M –1 for a 1:1 complex) and in near-quantitative emission quenching (λ ex = 325 nm, λ em = 410 nm).…”

Efficient fluorescent recognition of ATP/GTP by a water-soluble bisquinolinium pyridine-2,6-dicarboxamide compound. Crystal structures, spectroscopic studies and interaction mode with DNA

“…These receptors also frequently require an organic cosolvent to operate, which seriously limits their intended applications. Optical recognition of ATP or GTP by molecular hosts in water can be achieved with uorescent imidazolium salts, 14,18,27 cyclophanes, 19,29 quinoline-based Zn-complexes, 3,32 lanthanide complexes 4 and bis-2,6-formylphenol derivatives. 16 These luminescent receptors undergo changes in their photophysical properties due to the binding of the polyphosphate motif with the hydrogen bond donors or by coordination to the metal center.…”

A water-stable luminescent Zn-MOF based on a conjugated π-electron ligand as an efficient sensor for atorvastatin and its application in pharmaceutical samples

“…For practical applications, luminescent statin-sensors are required to have not only a good optical response but also selectivity in the presence of coexistent potential interferences in physiological samples. 75 Therefore, a selectivity experiment of 1 toward common interfering species in blood plasma and urine, such as d -glucose, creatinine, urea, l -proline, ATP, NaCl, KCl, NH 4 Cl, MgCl 2 , and HCO 3 − , was carried out at neutral pH.…”