Characterization and Water-Proton Longitudinal Relaxivities of Liposome-Type Radical Nanoparticles Prepared via a Supramolecular Approach

Ryoma Shiraishi, Shota Matsumoto, Yasufumi Fuchi, Tatsuya Naganuma, Daisuke Yoshihara, Kazuteru Usui, Ken Ichi Yamada, Satoru Karasawa

Research output: Contribution to journalArticle

Abstract

For the construction of metal-free magnetic resonance imaging (MRI) contrast agents, radical-based nanoparticles (RNPs) are promising materials because they allow the water-proton longitudinal relaxivity (r1) to be enhanced not only by paramagnetic resonance effects but also by prolonging the rotational correlation times (τR). However, the τR effect is limited because the radical units are often located within the central hydrophobic core of oil-in-water (o/w) emulsions, resulting in a lack of water molecules surrounding the radical units. In this study, to construct supramolecular RNPs that have high r1 values, we designed a liposome-type RNP in which the radical units are located at positions with sufficient surrounding water molecules. Using this strategy, PRO1 with a PROXYL framework was prepared by introducing hydrophilic groups on both sides of the radical unit. The RNP composed of PRO1 formed spherical nanoparticles approximately 100 nm in size and yielded a higher r1 value (0.26 mM-1 s-1) compared to those of small radical species and similar supramolecular o/w emulsion-type nanoparticles (0.17 mM-1 s-1 in PRO2).

Original languageEnglish
Pages (from-to)5280-5286
Number of pages7
JournalLangmuir
Volume36
Issue number19
DOIs
Publication statusPublished - May 19 2020

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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