Water-Proton Relaxivities of Radical Nanoparticles Self-Assembled via Hydration or Dehydration Processes

Kosuke Morishita, Yuna Okamoto, Shuhei Murayama, Kazuteru Usui, Eriko Ohashi, Go Hirai, Ichio Aoki, Satoru Karasawa

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Nanoparticles capable of accumulating in tumor tissues are promising materials for tumor imaging and therapy. In this study, two radical nanoparticles (RNPs), denoted as 1 and 2, composed of self-assembled ureabenzene derivatives possessing one or two amphiphilic side chains were demonstrated to be candidates for metal-free functional magnetic resonance imaging (MRI) contrast agents (CAs). Because of the self-assembly behavior of 1 and 2 in a saline solution, spherical RNPs of sizes ∼50-90 and ∼30-100 nm were detected. In a highly concentrated solution, RNP 1 showed considerably small water-proton relaxivity values (r1 and r2), whereas RNP 2 showed an r1 value that was around 5 times larger than that of RNP 1. These distinct r1 values might be caused by differences in the self-assembly behavior by a hydration or dehydration process. In vivo studies with RNP 2 demonstrated a slightly enhanced T1-weighted image in mice, suggesting that the RNPs can potentially be used as metal-free functional MRI CAs for T1-weighted imaging.

Original languageEnglish
Pages (from-to)7810-7817
Number of pages8
Issue number31
Publication statusPublished - Aug 8 2017

All Science Journal Classification (ASJC) codes

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


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