@article{oai:repo.qst.go.jp:00048832,
 author = {Morishita, Kosuke and Yuna, Okamoto and Murayama, Shuhei and Usui, Kazuteru and Eriko, Ohashi and Hirai, Go and Aoki, Ichio and Karasawa, Satoru and 村山 周平 and 青木 伊知男},
 issue = {31},
 journal = {Langmuir},
 month = {Jul},
 note = {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.},
 pages = {7810--7817},
 title = {Water-Proton Relaxivities of Radical Nanoparticles Self-Assembled via Hydration or Dehydration Processes},
 volume = {33},
 year = {2017}
}