Luminescence resonance energy transfer in hybrid materials based on terbium(iii) complex, rhodamine B and nanoclay

We prepared a novel kind of luminescent hydrogel based on the combination of terbium(iii) complexes and rhodamine B dye with the LAPONITE® nanoclay.

Lectin-carbohydrate complex evaluation by chemiluminescence

In order to characterize the affinity between specific carbohydrate-binding proteins such as lectins, a model is proposed to study these interactions using a polysaccharide membrane to simulate such adsorption. Here, lectin-carbohydrate interactions were chemiluminescently investigated using lectins conjugated to acridinium ester (AE) and polysaccharides composed of their respective specific carbohydrates. The lectin-AE conjugates were incubated with discs (0.0314-0.6358 cm²) of phytagel, chitosan and carrageenan. The complex formation chemiluminescently detected followed the Langmuir isotherm from which constants were estimated. The association constant (K_a) and maximum binding sites on the membranes were 2.4 × 10^-7 M^-1 ± 0.8 × 10^-7 M^-1 and 1.3 × 10^-3 mol. mg^-1 ± 0.3 × 10^-3 mol. mg^-1 (Con A); 0.9 × 10^-6 M^-1 ± 0.4 × 10^-6 M^-1 and 0.021 × 10^-3 mol. mg^-1 ± 0.003 × 10^-3 mol. mg^-1 (WGA) and 2.0 × 10^-6 M^-1 ± 0.9 × 10^-6 M^-1 and 0.069 × 10^-3 mol. mg^-1 ± 0.010 × 10^-3 mol. mg^-1 (PNA). The proposed model might be useful to study binding affinity and estimate the amount of binding not limited by the sugar content in the membrane.

Water-soluble lanthanide complexes with a helical ligand modified for strong luminescence in a wide pH region

Luminescent helical lanthanide complexes with hydrophilicity were examined for stability and reversibility in a pH region between 1.9 and 11.9.

Folic acid-conjugated europium complexes as luminescent probes for selective targeting of cancer cells

We report the synthesis of three optical probes (Eu(3+)⊂1, Eu(3+)⊂2, and Eu(3+)⊂3) having a luminescent Eu complex (signaling unit) bonded in different positions to folic acid (FA), the folate receptor (FR) targeting unit. The structures of the two regioisomers Eu(3+)⊂1 and Eu(3+)⊂2 were assigned by mass spectrometric experiments. The optical properties and stability of these probes were assessed in phosphate-buffered saline, cell culture medium, rat serum, and cellular lysate, and results indicated that they are chemically and photophysically stable. Cytotoxicity was studied with ovarian cancer cells having high (SKOV-3), intermediate (OVCAR-3), low (IGROV-1), or null (A2780) expression of FRs. The internalized probe, evaluated in SKOV-3, IGROV-1, and A2780 cells, was in the order Eu(3+)⊂2 > Eu(3+)⊂1 > Eu(3+)⊂3. No internalization was observed for A2780 cells. Such results, together with those obtained in competition experiments of FA versus Eu(3+)⊂2 and FA or Eu(3+)⊂2 versus (3)H-FA, indicate that internalization is receptor-mediated and that Eu(3+)⊂2 shows high selectivity and specificity for FR.

A macrocyclic tetraamine bearing four phenol groups: a new class of heptadentate ligands to provide an oxygen-sensitive luminescent Tb(iii) complex with an extendable phenol pendant arm

The potentially N₄O₄-octadentate ligand unprecedentedly coordinates to the Tb³⁺ion in a N₄O₃-heptadentate fashion and provides a highly luminescent and highly oxygen-sensitive terbium(iii) complex.