Application of Circularly Polarized Luminescence Spectroscopy to Tb(III) and Eu(III) Complexes of Transferrins

Abstract

Circularly polarized luminescence (CPL) and total luminescence of Tb(III) and Eu(III) as substitutional replacements for iron in a series of Fe binding transferrins are reported. The measurement of the total emission intensity is a direct measure of binding of the lanthanide ions and illustrates that approximately 2 equiv of Tb(III) and Eu(III) is bound to these proteins. In agreement with previous work, circularly polarized luminescence from Tb(III) bound to the transferrins is quite large. Additional measurements show that the net CPL displays no dependence on concentration of the metal ion and shows little variation between the two binding sites. CPL from lactoferrin is very similar to serum transferrin, however, ovotransferrin shows differences in line shape and magnitude. These results are discussed in the context of the previously published crystal structure of the binding sites of the three proteins.

Brilliant Sm, Eu, Tb, and Dy Chiral Lanthanide Complexes with Strong Circularly Polarized Luminescence

“…As examples, the conformational changes in calcium and iron binding proteins have been investigated using Tb(III) and Eu(III) ions as structural probes, a proof of principle that measurements such as these provide highly specific local information on the chiral environment of the lanthanide metal ion. 5,6 This information is thus a crucial complement to that obtained through the analogous but much less sensitive chirooptical absorption technique, circular dichroism (CD), which is often used to determine macromolecular information such as a protein's secondary and tertiary structure. 7,8 Due to the lanthanides' electronic structure, their complexes have unique optical properties, including luminescence lifetimes that range from micro-to milliseconds, and sharp emission bands whose width at half-height (fwhm) rarely exceed 10 nm.…”

A Smart Sensing Method for Object Identification Using Circularly Polarized Luminescence from Coordination‐Driven Self‐Assembly

“…[6,7] In most cases,high affinity to the target, longer wavelength detection, or time-gating detection excludes as ignal from non-target species.Onthe other hand, circularly polarized luminescence has been used in an optical technique to prove the excitedstate chirality, [8][9][10][11][12] but has yet to be fully exploited in ac onventional sensor application for achiral analytes. [6,7] In most cases,high affinity to the target, longer wavelength detection, or time-gating detection excludes as ignal from non-target species.Onthe other hand, circularly polarized luminescence has been used in an optical technique to prove the excitedstate chirality, [8][9][10][11][12] but has yet to be fully exploited in ac onventional sensor application for achiral analytes.…”

“…Herein, we propose ap otential application of circularly polarized luminescence for object identification in as ensor technology.L uminescence sensors are one of the common analytic tools for detection of the target analytes. [6,7] In most cases,high affinity to the target, longer wavelength detection, or time-gating detection excludes as ignal from non-target species.Onthe other hand, circularly polarized luminescence has been used in an optical technique to prove the excitedstate chirality, [8][9][10][11][12] but has yet to be fully exploited in ac onventional sensor application for achiral analytes. Scheme 1s hows an outline of the procedure for the CPLdriven luminescent sensing system demonstrated here.Inthe present system, the chiral probe exhibits circularly polarized luminescence (CPL, I L ¼ 6 I R )u pon binding to the target analyte.C onversely,n on-target species show non-polarized luminescence (NPL, I L = I R ), which can be eliminated by CPL measurement because non-polarized luminescence can be considered as equal amount of left and right circularly polarized light (that is, I L ÀI R = 0).…”

A Smart Sensing Method for Object Identification Using Circularly Polarized Luminescence from Coordination‐Driven Self‐Assembly

“…In most cases, high affinity to the target, longer wavelength detection, or time‐gating detection excludes a signal from non‐target species. On the other hand, circularly polarized luminescence has been used in an optical technique to prove the excited‐state chirality, but has yet to be fully exploited in a conventional sensor application for achiral analytes. Scheme shows an outline of the procedure for the CPL‐driven luminescent sensing system demonstrated here.…”