Development of MRI/NIRF 'activatable' multimodal imaging probe based on iron oxide nanoparticles

Eui Joon Cha, Eue Soon Jang, In Cheol Sun, In Joon Lee, Jeong Hoon Ko, Young Il Kim, Ick Chan Kwon, Kwangmeyung Kim, Cheol Hee Ahn

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


A fabrication method of Cy5.5-MMP substrate and PEG conjugated iron oxide nanoparticles with thin silica coating (PCM-CS) and its potential as an 'activatable' dual imaging probe for tumor imaging is described in this report. PCM-CS showed an intensity-averaged diameter of 43.1 ± 6.3 nm by dynamic light scattering without any noticeable aggregation over 7 days. Fluorescence of Cy5.5 on the surface of nanoparticles was fully quenched and the quenching efficiency was 97.2%. PCM-CS showed protease specific fluorescence recovery in vitro caused from the specific peptide cleavage by MMP-2 and the probe displayed the sensitivity on 0.5 nM or less enzyme concentration. Tumor was successfully visualized by NIRF and MRI in vivo by intravenously injected PCM-CS. NIRF signal of tumor was gradually increased up to 12 h post injection and the intensity of tumor was about 3-4 times higher than normal tissue. NIRF signal at MMP-2 inhibitor treated tumor was clearly lower than tumor without inhibitor due to the insufficient peptide cleavage. NIRF signal at excised tumor was 5-10 times stronger than other organs. Noticeable darkening in magnetic resonance image was observed at the tumor region and the image was gradually darkened at 12 h post injection of PCM-CS. The maximum signal difference between tumor region and healthy muscle was 34%.

Original languageEnglish
Pages (from-to)152-158
Number of pages7
JournalJournal of Controlled Release
Issue number2
StatePublished - 30 Oct 2011

Bibliographical note

Funding Information:
This work was supported by Basic Science Research Program ( 2010–0027955 ) and Converging Research Center Program ( 2009–0081879 ) through the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST).


  • Activatable
  • Core-shell nanoparticle
  • Dual imaging
  • Iron oxide
  • MRI
  • Optical imaging


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