Taylor dispersion analysis for measurement of diffusivity and size of gadolinium-based contrast agents

Gadolinium-based contrast agents (GBCA) are complexes of a Gadolinium metal center and a linear or macrocyclic polyamino-carboxylic acid chelating agent. These agents are employed to enhance the visibility of deep abnormalities through MRI techniques. Knowing the precise dimensions of various GBCA is key parameter for understanding their in-vivo and pharmaco-kinetic behaviors, their diffusivity, as well as their relaxivity. However, conventional size characterization techniques fall short when dealing with these tiny molecules (≤1 nm). In this work, we propose to determine the size and diffusivity of gadolinium-based contrast agents using Taylor dispersion analysis (TDA). TDA provided a reliable measurement of the hydrodynamic diameter and the diffusion coefficient. The obtained results were compared to DOSY NMR (Diffusion-ordered Nuclear Magnetic Resonance Spectroscopy) and DFT (Density Functional Theory).