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This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Chen, K. Articles by Chen, X. PubMed Articles by Chen, K. Articles by Chen, X.

Quantum dot based dual functional probe for optical/PET imaging of tumor VEGFR

¹ Stanford U, Stanford, California

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Objectives: To date, the in vivo imaging of quantum dots (QDs) has been mostly qualitative or semiquantitative. It is needed to develop a dual-function PET/near-infrared fluorescence (NIRF) probe for accurate assessment of tumor-targeting efficacy of QDs.

Methods: QD705 surface was conjugated with DOTA chelator for ⁶⁴Cu-labeling and PET imaging, and with VEGF₁₂₁ protein for VEGFR-2 targeting in a subcutaneous U87MG tumor model. The efficiency of this optical/PET dual functional probe was evaluated in vitro, in vivo, and ex vivo.

Results: DOTA-QD-VEGF₁₂₁ binds VEGFR-2 with high affinity and specificity based on competitive cell binding assay and fluorescence cell staining. Both NIRF and PET imaging of ⁶⁴Cu-DOTA-QD705-VEGF₁₂₁ demonstrated quick tumor contrast and increased tumor signal with time, however, optical imaging is qualitative while PET imaging is quantitative. Prominent RES uptake (liver, spleen and lymph nodes) was also observed. ⁶⁴Cu-DOTA-QD705 on the other hand did not show any visible tumor uptake throughout the experiment. Ex vivo PET and NIRF imaging were also carried out to further confirm the in vivo imaging results in major organs. Immunofluorescence staining of VEGFR2 on frozen U87MG tumor section confirmed that ⁶⁴Cu-DOTA-QD705-VEGF₁₂₁ specifically targets the tumor vasculature through VEGF/VEGFR-2 binding and only a very small fraction of QD may extravasate.

Conclusions: This is the first study to use QD-based NIRF imaging and PET imaging to specifically target tumor vascular VEGFR-2 and quantitatively evaluate the targeting efficacy.

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Chen, K. Articles by Chen, X. PubMed Articles by Chen, K. Articles by Chen, X.