Europium (III) as a Circularly Polarized Luminescence Probe of DNA Structure

Abstract

We report as a proof-of-concept the first application of circularly polarized luminescence (CPL) measured with a Raman optical activity (ROA) spectrometer to differentiate several DNA structures without need of sensitizing complexes. The ROA/CPL approach provides sufficiently high CPL intensity to use hydrated Eu3+ ions, thus avoiding DNA structural changes associated with binding of sensitizers and overcoming the sensitizer quenching issue. We showed that deoxyguanosine monophosphate (dGMP), single- and double-stranded DNA provide different CPL spectra, which could be used for their discrimination. Our results demonstrate that ROA/CPL method is a promising approach to measure CPL spectra of complex biomolecules when the use of sensitizers is not possible. The method can be extended to other biomolecules, such as proteins, lipids, sugars, etc.

Binuclear Lanthanide(III) Complexes with Chiral Ligands: Dynamic Equilibria in Solution and Binding with Nucleotides Studied by Spectroscopic Methods

“…The CPL spectral shape of [Eu‐ L ]‐ATP is similar to that for Eu 3+ aqua ions chelating with double stranded DNA . Experiment with EuCl 3 and the three phosphates gave, however, a different CPL signal (Figure S13), revealing that the binding mode between [Eu‐ L ] 3+ and Eu 3+ aqua ions are different.…”

“…Particularly intense are the 5 D 0 → 7 F 0 and 5 D 0 → 7 F 1 europium transitions. Recently, we used the CPL/ROA technique for lanthanide‐based sensing of biomolecules such as amino acids and proteins, oligopeptides, saccharides, and nucleic acids …”

Chirogenesis and Pfeiffer Effect in Optically Inactive EuIII and TbIII Tris(β-diketonate) Upon Intermolecular Chirality Transfer From Poly- and Monosaccharide Alkyl Esters and α-Pinene: Emerging Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD)

“…In 1977, the first circularly polarized luminescence (CPL) spectra from optically inactive Eu III (fod) 3 , Eu III (dpm) 3 , Tb III (fod) 3 , and other two Eu II complexes dissolved in ( R )-/( S )-α-phenylethylamine are reported by hypothesizing the Pfeiffer effect (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate, dpm: dipivaloylmethane or 2,2,6,6-tetramethyl-3,5-heptanedione) (Brittain and Richardson, 1977a ; Brittain, 1980 ). These pioneering CPL studies further stimulated many researchers to investigate CPL and CD spectroscopic characteristics of optically inactive lanthanide complexes in the presence of amino acids, monosaccharides, malic acid ascorbic acid, cyclic glycols, DNA, and other chiral chemical influences (Luk and Richardson, 1974 ; Brittain and Richardson, 1977b ; Madaras and Brittain, 1980 ; Brittain, 1981 , 1984 ; Richardson, 1982 ; Yan et al, 1982 ; Huskowska and Riehl, 1995 ; Muller and Riehl, 2005 ; Muller, 2009 ; Iwamura et al, 2012 , 2016 ; Miyake et al, 2014 ; Wu et al, 2016 , 2019 ; Jalilah et al, 2018 ; Lunkley et al, 2018 ; Wu and Bouř, 2018 ; Taniguchi et al, 2019 ). An outer-sphere intermolecular interaction between the Δ-/Λ-mixture lanthanide III (Ln III ) complex and the chiral additives is responsible for the equilibrium shift, as detectable by emerging CPL spectra.…”

Recent Trends in Chiroptical Spectroscopy: Theory and Applications of Vibrational Circular Dichroism and Raman Optical Activity

“…One can consider different polarization schemes, excitation not only with visible and UV, but also red and near IR light, or combination of ROA with circular polarized luminescence (CPL) . In particular, induced or magnetic CPL of lanthanides seem to be sensitively probing complex environment and well suitable for measurements with common ROA instruments . Newest ROA spectrometers also measure as down as to ∼50 cm −1 or up to 4000 cm −1 , which brings new information about the molecules as well as new challenges to computational chemistry and theory …”