Near-infrared fluorescent type II quantum dots for sentinel lymph node mapping
Sungjee Kim1, 6
, Yong Taik Lim2, 5, 6
, Edward G Soltesz3
, Alec M De Grand2
, Jaihyoung Lee2
, Akira Nakayama2
, J Anthony Parker4
, Tomislav Mihaljevic3
, Rita G Laurence3
, Delphine M Dor3
, Lawrence H Cohn3
, Moungi G Bawendi1
& John V Frangioni2, 4
1. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
2. Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
3. Division of Cardiac Surgery, Department of Surgery, Brigham and Women''s Hospital, Boston, Massachusetts 02115, USA.
4. Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
5. Present address: Electronics and Telecommunications Research Institute, 161 Gajeong-dong, Yuseong-gu, Daejeon, 305-350, Republic of Korea.
6. These authors contributed equally to this study.
Correspondence should be addressed to J V Frangioni.
The use of near-infrared or infrared photons is a promising approach for biomedical imaging in living tissue1. This technology often requires exogenous contrast agents with combinations of hydrodynamic diameter, absorption, quantum yield and stability that are not possible with conventional organic fluorophores. Here we show that the fluorescence emission of type II2, 3 quantum dots can be tuned into the near infrared while preserving absorption cross-section, and that a polydentate phosphine coating renders them soluble, disperse and stable in serum. We then demonstrate that these quantum dots allow a major cancer surgery, sentinel lymph node mapping4-6, to be performed in large animals under complete image guidance. Injection of only 400 pmol of near-infrared quantum dots permits sentinel lymph nodes 1 cm deep to be imaged easily in real time using excitation fluence rates of only 5 mW/cm2. Taken together, the chemical, optical and in vivo data presented in this study demonstrate the potential of near-infrared quantum dots for biomedical imaging.