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Self-assembled Ln(III) cyclen-based micelles and AuNPs conjugates as candidates for luminescent and magnetic resonance imaging (MRI) agents
摘要： The tetra-substituted heptadentate cyclen (1,4,7,10-tetraazacyclododecane) based Eu(III)/Tb(III)/Gd(III)-complexes 1.Ln and 2.Ln were developed. 1.Eu/Tb and 2.Eu/Tb were employed in the formation of luminescent self-assembling ternary structures, and we demonstrate that only in the presence of appropriate sensitizing antennae, was the lanthanide-emission of 1.Eu/Tb and 2.Eu/Tb ‘switched on’. 1.Gd/2.Gd were developed as potential MIR contrast agents, and employed in NMRD-measurements, where their relaxivity was investigated, and their (relatively high) r1 values determined. The formation of a self-assembled micelle-type structure was clearly observed for 2.Gd. The functionalised gold nanoparticles 1.Ln-AuNP were also synthesized from 1.Ln. As for the free complexes, the Ln-emission was ‘switched on’ for 1.Eu/Tb-AuNP in the presence of the antennae. NMRD measurements indicated that the relaxivity for the 1.Gd-AuNP systems was very high, with a value of 445 s-1mM-1 (at 400 MHz), demonstrating the cumulative effect of the relatively high number of 1.Gd complexes on the surface of the AuNP.
关键词： gold nanoparticles,lanthanides,Supramolecular chemistry,luminescence,MRI contrast agents,cyclen complexes
更新于2025-09-23 15:19:57
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Spin–Lattice Relaxation and Diffusion Processes in Aqueous Solutions of Gadolinium-Based Upconverting Nanoparticles at Different Magnetic Fields
摘要： We investigated the influence of gadolinium (Gd)-based upconverting nanoparticles (UCNPs) on water spin–lattice relaxation (T1) and diffusion at different magnetic field strengths (0.4 T and 9.4 T). Our findings show that smaller NPs (12 nm compared to 19 nm) were more favourable for proton relaxivity. We also demonstrate that using simplified Solomon–Bloembergen–Morgan (SBM) model we can associate two measured diffusion coefficients with processes occurring near the surface of UCNPs and in bulk water. Using the relationship between relaxation and diffusion, we can estimate not only the total impact of NPs on relaxation of water molecules, but also the impact on relaxation of local water molecules, directly connected to paramagnetic Gd3+ ions in NPs. Different magnetic field strengths did not alter the spin–lattice relaxivity of NPs. This suggests that Gd-based UCNPs could be developed into high-performance multimodal magnetic resonance imaging contrast agents working over a broad range of imaging field strengths used in clinical routine.
关键词： Magnetic fields,MRI contrast agents,Gadolinium-based upconverting nanoparticles,Diffusion processes,Spin–lattice relaxation
更新于2025-09-04 15:30:14