NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.

Cover of Molecular Imaging and Contrast Agent Database (MICAD)

Molecular Imaging and Contrast Agent Database (MICAD) [Internet].

Show details

Gadolinium-G6 dendrimer-Cy5.5

, PhD
National for Biotechnology Information, NLM, NIH, Bethesda, MD

Created: ; Last Update: July 23, 2009.

Chemical name:Gadolinium-G6 dendrimer-Cy5.5
Abbreviated name:Gd-G6-Cy5.5
Agent category:Macromolecule, polymer
Target category:Non-targeted
Method of detection:Magnetic resonance imaging (MRI), optical, near-infrared (NIR) fluorescence imaging
Source of signal/contrast:Cy5.5, gadolinium (Gd)
  • Checkbox In vitro
  • Checkbox Rodents
No structure is available in PubChem.



Optical fluorescence imaging is increasingly being used to monitor biological functions of specific targets in small animals (1-3). However, the intrinsic fluorescence of biomolecules poses a problem when fluorophores that absorb visible light (350–700 nm) are used. Near-infrared (NIR) fluorescence (700–1,000 nm) detection avoids the natural background fluorescence interference of biomolecules, providing a high contrast between target and background tissues in small animals. NIR fluorophores have a wider dynamic range and minimal background fluorescence as a result of reduced scattering compared with visible fluorescence detection. NIR fluorophores also have high sensitivity, attributable to low background fluorescence, and high extinction coefficients, which provide high quantum yields. The NIR region is also compatible with solid-state optical components, such as diode lasers and silicon detectors. NIR fluorescence imaging is a non-invasive alternative to radionuclide imaging in small animals.

The sentinel lymph node (SLN) is considered to be the first lymph node to receive lymphatic flow from tumor sites and therefore will contain metastatic tumor cells (4). SLN mapping has been used in the diagnosis of metastasis of solid tumors (5). Radical lymph node dissection is performed in patients with malignant cells in the SLNs. SLN mapping is currently performed by a combination of radioactive tracer and blue dye with low spatial resolution. The current procedure is time-consuming and requires a steep learning curve. NIR quantum dots (QDs) have been studied in SLN mapping in small animals (6, 7). However, there are only limited studies of long-term toxicity of QDs in animals (8). Dendrimer consists of a core with concentric annular shells or generations (G1–G6) made of highly branched polymers, which contain numerous surface functional groups for additional modifications. Koyama et al. (9) prepared a G6 dendrimer tagged with Cy5.5 and gadolinium (Gd) for optical NIR fluorescence and magnetic resonance (MR) multimodal imaging of the SLNs.



G6 dendrimer (~9 nm in diameter) was conjugated with a two-fold molar excess of the bifunctional chelating agent 1B4M-diethylenetriaminepentaacetic acid (1B4M-DTPA) to form G6-1B4M dendrimer (9, 10). There were 142–191 1B4M-DTPA moieties per G6-1B4M dendrimer. Cy5.5-N-Hydroxysuccinimide ester was reacted with the free primary amines of G6-1B4M to form G6-1B4M-Cy5.5. Finally, G6-1B4M-Cy5.5 was incubated with Gd(OAc)3 in 0.3 M citrate buffer (pH 4.5) for 18 h for Gd complexing with the DTPA moieties in G6-1B4M-Cy5.5. Gd-G6-Cy5.5 was purified with dialysis. Gd-G6-Cy5.5 contained ~172 Gd ions and 2 Cy5.5 molecules per G6 dendrimer.

In Vitro Studies: Testing in Cells and Tissues


Talanov et al. (10) showed that Gd-G6-Cy5.5 (145 Gd, 1.25 Cy5.5) exhibited T1 and T2 relaxivity values of 13.9 and 36.5 mmol-1s-1, respectively.

Animal Studies



Koyama et al. (9) performed MR imaging (3 T) and NIR optical imaging in female nude mice (n = 10) after injection of Gd-G6-Cy5.5 into the left mammary pad. Thirty lymph nodes were examined in each mouse. For MR lymphography studies, a dose of 750 nmol Gd-G6-Cy5.5 was required to consistently visualize at least one SLN in the axillary region in 20–30 min after injection. On the other hand, only 1.2 nmol of Gd-G6-Cy5.5 was required to visualize the axillary SLNs with NIR imaging. When the skin was incised, all SLNs could be easily identified and distinguished from nearby non-SLNs on the basis of their fluorescence. There was a significant correlation (r = 0.86) of fluorescence signal of resected SLNs with MR lymphography measured in vivo and in vitro.

Other Non-Primate Mammals


No publication is currently available.

Non-Human Primates


No publication is currently available.

Human Studies


No publication is currently available.


Achilefu S. Lighting up tumors with receptor-specific optical molecular probes. Technol Cancer Res Treat. 2004;3(4):393–409. [PubMed: 15270591]
Ntziachristos V., Bremer C., Weissleder R. Fluorescence imaging with near-infrared light: new technological advances that enable in vivo molecular imaging. Eur Radiol. 2003;13(1):195–208. [PubMed: 12541130]
Becker A., Hessenius C., Licha K., Ebert B., Sukowski U., Semmler W., Wiedenmann B., Grotzinger C. Receptor-targeted optical imaging of tumors with near-infrared fluorescent ligands. Nat Biotechnol. 2001;19(4):327–31. [PubMed: 11283589]
Morton D.L., Wen D.R., Wong J.H., Economou J.S., Cagle L.A., Storm F.K., Foshag L.J., Cochran A.J. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg. 1992;127(4):392–9. [PubMed: 1558490]
Schulze T., Bembenek A., Schlag P.M. Sentinel lymph node biopsy progress in surgical treatment of cancer. Langenbecks Arch Surg. 2004;389(6):532–50. [PubMed: 15197548]
Frangioni J.V., Kim S.W., Ohnishi S., Kim S., Bawendi M.G. Sentinel Lymph Node Mapping With Type-II Quantum Dots. Methods Mol Biol. 2007;374:147–60. [PMC free article: PMC2496896] [PubMed: 17237537]
Zimmer J.P., Kim S.W., Ohnishi S., Tanaka E., Frangioni J.V., Bawendi M.G. Size series of small indium arsenide-zinc selenide core-shell nanocrystals and their application to in vivo imaging. J Am Chem Soc. 2006;128(8):2526–7. [PMC free article: PMC2753875] [PubMed: 16492023]
Pinaud F., Michalet X., Bentolila L.A., Tsay J.M., Doose S., Li J.J., Iyer G., Weiss S. Advances in fluorescence imaging with quantum dot bio-probes. Biomaterials. 2006;27(9):1679–87. [PMC free article: PMC3073483] [PubMed: 16318871]
Koyama Y., Talanov V.S., Bernardo M., Hama Y., Regino C.A., Brechbiel M.W., Choyke P.L., Kobayashi H. A dendrimer-based nanosized contrast agent dual-labeled for magnetic resonance and optical fluorescence imaging to localize the sentinel lymph node in mice. J Magn Reson Imaging. 2007;25(4):866–71. [PubMed: 17345640]
Talanov V.S., Regino C.A., Kobayashi H., Bernardo M., Choyke P.L., Brechbiel M.W. Dendrimer-based nanoprobe for dual modality magnetic resonance and fluorescence imaging. Nano Lett. 2006;6(7):1459–63. [PubMed: 16834429]
PubReader format: click here to try


Search MICAD

Limit my Search:

Related information

  • PMC
    PubMed Central citations
  • PubMed
    Links to pubmed

Related citations in PubMed

See reviews...See all...

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...