Dysprosium Complexes and Their Micelles as Potential Bimodal Agents for Magnetic Resonance and Optical Imaging

Abstract

Six diethylene triamine pentaacetic acid (DTPA) bisamide derivatives functionalized with p-toluidine (DTPA-BTolA), 6-aminocoumarin (DTPA-BCoumA), 1-naphthalene methylamine (DTPA-BNaphA), 4-ethynylaniline (DTPA-BEthA), p-dodecylaniline (DTPA-BC12PheA) and p-tetradecyl-aniline (DTPA-BC14PheA) were coordinated to dysprosium(III) and the magnetic and optical properties of the complexes were examined in detail. The complexes consisting of amphiphilic ligands (DTPA-BC12PheA and DTPA-BC14PheA) were further assembled into mixed micelles. Upon excitation into the ligand levels, the complexes display characteristic Dy(III) emission with quantum yields of 0.3-0.5% despite the presence of one water molecule in the first coordination sphere. A deeper insight into the energy-transfer processes has been obtained by studying the photophysical properties of the corresponding Gd(III) complexes. Since the luminescence quenching effect is decreased by the intervention of non-ionic surfactant, quantum yields up to 1% are obtained for the micelles. The transverse relaxivity r2 per Dy(III) ion at 500 MHz and 310 K reaches a maximum value of 27.4 s(-1) mM(-1) for Dy-DTPA-BEthA and 36.0 s(-1) mM(-1) for the Dy-DTPA-BC12PheA assemblies compared with a value of 0.8 s(-1) mM(-1) for Dy-DTPA. The efficient T2 relaxation, especially at high magnetic field strengths, is sustained by the high magnetic moment of the dysprosium ion, the coordination of water molecules with slow water exchange kinetics and long rotational correlation times. These findings open the way to the further development of bimodal optical and magnetic resonance imaging probes starting from single lanthanide compounds.

Structural insights in Dy3+‐doped β‐Tricalcium phosphate and its multimodal imaging characteristics

“…They can induce spin‐spin relaxation of the protons and thereby influence the values of T 2 in the MRI. Hence, Dy‐based materials exhibit high transverse relaxivity ( r 2 ) at high magnetic fields, which makes them appropriate candidate for the development of negative ( T 2 ) contrast agents …”

Enhanced energy transfer efficiency and stability of europium β-diketonate complex in ionic liquid-based lyotropic liquid crystals

“…[19][20][21][22][23] For example, a significant luminescence enhancement can be obtained in electrostatic micelles, formed between the negatively charged coordination compound Eu-L 2 EO 4 (1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane) and positively charged block polyelectrolytes. [19][20][21][22][23] For example, a significant luminescence enhancement can be obtained in electrostatic micelles, formed between the negatively charged coordination compound Eu-L 2 EO 4 (1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane) and positively charged block polyelectrolytes.…”

“…[19][20][21][22][23] For example, a significant luminescence enhancement can be obtained in electrostatic micelles, formed between the negatively charged coordination compound Eu-L 2 EO 4 (1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane) and positively charged block polyelectrolytes. 20 The antenna effect of Eu(III)-cyclen complexes trapped in micellar nanodomains of tetramethylammonium dodecylsulfate was found by McClenaghan et al to be more effective than in other chemical environments such as neat solutions, polymers or gels. 20 The antenna effect of Eu(III)-cyclen complexes trapped in micellar nanodomains of tetramethylammonium dodecylsulfate was found by McClenaghan et al to be more effective than in other chemical environments such as neat solutions, polymers or gels.…”

Multifunctional β-NaGdF4:Ln3+ (Ln = Yb, Er, Dy) nanoparticles with NIR to visible upconversion and high transverse relaxivity: a potential bimodal contrast agent for high-field MRI and optical imaging

“…However, bimodal contrast agents targeting high eld MRI applications are very rare. 24,25 In fact, to the best of our knowledge, there are no reports on Dy 3+ based bimodal T 2 CAs capable of exciting in the biological window. Thus in the present study we developed a series of water dispersible AC/ASUCNPs based on NaGdF 4 doped with Yb 3+ /Er 3+ in the core and Yb 3+ /Dy 3+ in the shell and a systematic study of the effect of Dy 3+ concentration on upconversion emission and transverse relaxivity has been conducted.…”