A 365 nm UV LED-excitable antenna ligand for switchable lanthanide luminescence

Abstract

The time-resolved luminescence of lanthanide complexes is a highly sensitive and widely used bioassay technology for clinical diagnostics. With the time-resolved luminescence detection the naturally occurring autofluorescence of biological matrices, solid supports and plastics can be avoided. A major drawback of the current technique is that the luminescent lanthanide labels require ultraviolet (UV) excitation, typically shorter than 360 nm, which is strongly absorbed and can damage living biological systems. The lack of cost-efficient high power solid state excitation light sources for UV excitation further limits the development of low-cost and more compact measurement instruments for time-resolved luminescence and the potential use of lanthanide luminescence in different applications. Switchable lanthanide luminescence is a binary probe technology that inherently enables a high signal modulation in a separation-free detection of targets. The intrinsically luminescent lanthanide chelate is split into two nonluminescent moieties, a lanthanide ion carrier chelate and a light harvesting antenna ligand, each of which can be attached to a separate molecular probe. A luminescent lanthanide complex is formed only when the two probes bind adjacently to the target molecule. Herein we describe a new 365 nm excitable antenna ligand (AL360) for switchable lanthanide luminescence of europium(iii) (Eu) that would enable the use of 365 nm light emitting diodes (LEDs) as an excitation light source for time-resolved fluorescence imaging and detection. With the acquired subpicomolar assay sensitivity it would be applicable for solution or surface arrays and UV LED microscopy.

Terbium Tetra‐Sulfosalicylate Complex as Quantitative Luminescent Sensing of Chromate Ions with High Selectivity and Sensitivity

“…Conjugated organic ligands are used as chromophores to ensure efficient energy transfer from the ligand to the lanthanide ion through the antenna effect. 11,12 Therefore, the selection of suitable ligands containing the characteristics of flexibility and multifunctional binding modes plays an important role in the construction of complexes. The selection of the ligand 5-sulfosalicylic (SSA) can be attributed to the following reasons: (a) It has three potential coordinating groups: -COOH, -SO 3 H, and -OH, and the oxygen atom on the group can coordinate with Ln (III) ion, 13 (b) SSA has a high structuring effect, its p-system and donor oxygen atoms participate in hydrogen bonds, the aromatic ring transfers the excited-state energy of SSA to lanthanide luminescence center(antenna effect) as a sensitizer.…”

“…However, lanthanide‐based fluorescence must surmount the problem of La Porte‐forbidden f–f transitions. Conjugated organic ligands are used as chromophores to ensure efficient energy transfer from the ligand to the lanthanide ion through the antenna effect . Therefore, the selection of suitable ligands containing the characteristics of flexibility and multifunctional binding modes plays an important role in the construction of complexes.…”

Lanthanide conjugates as versatile instruments for therapy and diagnostics

“…1 Lanthanide luminescence results from Laporte-forbidden f-f-transitions that result in long-lived excited states, but also need organic receptors that transfer energy towards the metal centre. [2][3][4][5] This so-called antenna effect is crucial as the rare earths are characterized by low absorption coefficients. Due to versatile luminescence properties along the lanthanide row, 6,7 a broad range of emission wavelengths is covered by choosing an appropriate representative.…”