Activatable cell penetrating peptides linked to nanoparticles as dual probes for in vivo fluorescence and MR imaging of proteases

Emilia S. Olson, Tao Jiang, Todd A. Aguilera, Quyen T. Nguyen, Lesley G. Ellies, Miriam Scadeng, Roger Y. Tsien

Research output: Contribution to journalArticlepeer-review

487 Scopus citations


High-resolution imaging of molecules intrinsically involved in malignancy and metastasis would be of great value for clinical detection and staging of tumors. We now report in vivo visualization of matrix metalloproteinase activities by MRI and fluorescence of dendrimeric nanoparticles coated with activatable cell penetrating peptides (ACPPs), labeled with Cy5, gadolinium, or both. Uptake of such nanoparticles in tumors is 4- to 15-fold higher than for unconjugated ACPPs. With fluorescent molecules, we are able to detect residual tumor and metastases as small as 200 μm, which can be resected under fluorescence guidance and analyzed histopathologically with fluorescence microscopy. We show that uptake via this mechanism is comparable to that of other near infrared protease sensors, with the added advantage that the approach is translatable to MRI. Once activated, the Gd-labeled nanoparticles deposit high levels (30-50 μM) of Gd in tumor parenchyma with even higher amounts deposited in regions of infiltrative tumor, resulting in useful T1 contrast lasting several days after injection. These results should improve MRI-guided clinical staging, presurgical planning, and intraoperative fluorescence-guided surgery. The approach may be generalizable to deliver radiation-sensitizing and chemotherapeutic agents.

Original languageEnglish (US)
Pages (from-to)4311-4316
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number9
StatePublished - Mar 2 2010


  • Dendrimeric nanoparticles
  • Molecular amplification
  • Molecular navigation
  • Targeted imaging agent
  • Transgenic tumor model

ASJC Scopus subject areas

  • General


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