Relaxivity Enhancement of Hybrid Micelles via Modulation of Water Coordination Numbers for Magnetic Resonance Lymphography.

Jiang, Yuting; Cai, Zhongyuan; Fu, Shengxiang; Gu, Haojie; Fu, Xiaomin; Zhu, Jiang; Ke, Yubin; Jiang, Hanqiu et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Considerable efforts have been made to develop nanoparticle-based magnetic resonance contrast agents (CAs) with high relaxivity. The prolonged rotational correlation time (τ<sub>R</sub>) induced relaxivity enhancement is commonly recognized, while the effect of the water coordination numbers (<i>q</i>) on the relaxivity of nanoparticle-based CAs gets less attention. Herein, we first investigated the relationship between <i>T</i><sub>1</sub> relaxivity (<i>r</i><sub>1</sub>) and <i>q</i> in manganese-based hybrid micellar CAs and proposed a strategy to enhance the relaxivity by increasing <i>q</i>. Hybrid micelles with different ratios of amphiphilic manganese complex (MnL) and DSPE-PEG2000 were prepared, whose <i>q</i> values were evaluated by Oxygen-17-NMR spectroscopy. Micelles with lower manganese doping density exhibit increased <i>q</i> and enhanced relaxivity, corroborating the conception. <i>In vivo</i> sentinel lymph node (SLN) imaging demonstrates that DSPE-PEG/MnL micelles could differentiate metastatic SLN from inflammatory LN. Our strategy makes it feasible for relaxivity enhancement by modulating <i>q</i>, providing new approaches for the structural design of high-performance hybrid micellar CAs.

Medical subject headings