Fluorescence and Electrochemical Recognition of Nucleosides and DNA by A Novel Luminescent Bioprobe Eu(lll) -TNB

Abstract

The luminescence arising from lanthanide cations offers several advantages over organic fluorescent molecules: sharp, distinctive emission bands allow for easy resolution between multiple lanthanide signals; long emission lifetimes (μs -ms) make them excellent candidates for time-resolved measurements; and high resistance to photo bleaching allow for long or repeated experiments. A method is presented for determination of nucleosides using the effect of enhancement of fluorescence of the easily accessible europium(III)-TNB in presence of different nucleosides. The latter coordinates to Eu(III) -TNB and enhances its luminescence intensity as a result of the displacement of water from the inner coordination sphere of the central metal. A similar method for the determination of DNA based on the quenching of Eu(III)-TNB has been established. The interaction of Eu(III)-4,4,4 trifluoro-1-(2-naphthyl)1,3-butanedione (TNB) complex with nucleosides (NS) (guanosine, adenosine, cytidine, inosine) and DNA has been studied using normal and time-resolved luminescence techniques. Binding constants were determined at 293 K, 298 K, 303 K, 308 K and 313 K by using Benesi-Hildebrand equation. A thermodynamic analysis showed that the reaction is spontaneous with ΔG being negative. The enthalpy ΔH and the entropy ΔS of reactions were all determined. The formation of binary and ternary complexes of Eu(III) with nucleosides and TNB has been studied potentiometrically at (25.0 ± 0.1) °C and ionic strength I = 0.1 mol.dm(-3) (KNO3) . The formation of the 1:1 binary and 1:1:1 ternary complexes are inferred from the corresponding titration curves. Initial estimates of the formation constants of the resulting species and the protonation constants of the different ligands used have been refined with the HYPERQUAD computer program. Electrochemical investigations for the systems under investigations have been carried out using cyclic voltammetry (CV), differential pulse polarography (DPP), and square wave voltammetry (SWV) on a glassy carbon electrode in I = 0.1 mol/L p-toluenesulfonate as supporting electrolyte.

Time-resolved fluorescence sensing of pesticides chlorpyrifos, crotoxyphos and endosulfan by the luminescent Eu(III)–8-allyl-3-carboxycoumarin probe

“…Due to the structural similarity of pesticide compounds, it is also paramount that the designed sensors must be fabricated such that they are highly selective toward specific pesticide compounds. This work represents a continuation of our work in the field of development of novel luminescent sensors for environmental and biomedical applications [23][24][25][26][27][28][29].…”

Mononuclear Co(III) and Ni(II) Complexes with Polypyridyl Ligands, [Co(phen)2(taptp)]3+ and [Ni(phen)2(taptp)]2+: Synthesis, Photocleavage and DNA-binding

“…Synthesis of [Co(phen) 2 (taptp)](PF 6 ) 3 (1) taptp (0.38 g, 1 mmol) was dissolved in 100 ml acetonitrile and refluxed then [Co(phen) 2 Cl 2 ]Cl (0.58 g, 1 mmol) dissolved in 25 ml ethanol was added to the solution. The resulting mixture was refluxed for 4 h, allowed to cool to room temperature and then filtered.…”

“…Elemental analyses were performed on a Perkin-Elmer 2400 CHNS/O elemental analyzer Electronic spectra were recorded using a CARY 100 Bio VARIAN UV-vis spectrophotometer. 1 H NMR spectra were recorded on a Bruker FT-NMR 500 (500 MHz) Ultra Shield spectrometer at ambient temperature DMSO-d6. Fluorescence measurements were made on a Cary Eclipse spectrophotometer equipped with quartz cuvettes of 1 cm path length.…”

“…Nucleic acid binding metal complexes are currently being investigated in many laboratories because of their utility as DNA structural probes, DNA dependent electron transfer probes, DNA foot printing and sequence-specific cleaving agents and potential anticancer drugs [1][2][3][4]. Metal complexes of 1,10-phenanthroline (phen) or modified phen ligands are particularly attractive species for developing new diagnostic and therapeutic agents that can recognize and cleave DNA [5].…”

Synthesis, characterization and DNA-Binding properties of the novel mononuclear Zn(II), Cd(II), and Mn(II) complexes with Pantoprazole

“…Deoxyribonucleic acid (DNA) is the primary target molecule for most anticancer and antiviral therapies according to cell biology 16,17 . Investigations of the interaction between small molecules and DNA are basic work in the design of new types of pharmaceutical molecules [18] .…”