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Synthesis and Characterization of Anti-HER2 Antibody Conjugated CdSe/CdZnS Quantum Dots for Fluorescence Imaging of Breast Cancer Cells
WPI Immunology Frontier Research Center, Osaka University, Yamada-oka 1-3, Suita, Osaka 565-0871, Japan
Graduate School of Frontier Biosciences, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan
* Author to whom correspondence should be addressed.
Received: 21 September 2009; in revised form: 3 November 2009 / Accepted: 12 November 2009 / Published: 19 November 2009
Abstract: The early detection of HER2 (human epidermal growth factor receptor 2) status in breast cancer patients is very important for the effective implementation of anti-HER2 antibody therapy. Recently, HER2 detections using antibody conjugated quantum dots (QDs) have attracted much attention. QDs are a new class of fluorescent materials that have superior properties such as high brightness, high resistance to photo-bleaching, and multi-colored emission by a single-light source excitation. In this study, we synthesized three types of anti-HER2 antibody conjugated QDs (HER2Ab-QDs) using different coupling agents (EDC/sulfo-NHS, iminothiolane/sulfo-SMCC, and sulfo-SMCC). As water-soluble QDs for the conjugation of antibody, we used glutathione coated CdSe/CdZnS QDs (GSH-QDs) with fluorescence quantum yields of 0.23~0.39 in aqueous solution. Dispersibility, hydrodynamic size, and apparent molecular weights of the GSH-QDs and HER2Ab-QDs were characterized by using dynamic light scattering, fluorescence correlation spectroscopy, atomic force microscope, and size-exclusion HPLC. Fluorescence imaging of HER2 overexpressing cells (KPL-4 human breast cancer cell line) was performed by using HER2Ab-QDs as fluorescent probes. We found that the HER2Ab-QD prepared by using SMCC coupling with partially reduced antibody is a most effective probe for the detection of HER2 expression in KPL-4 cells. We have also studied the size dependency of HER2Ab-QDs (with green, orange, and red emission) on the fluorescence image of KPL-4 cells.
Keywords: quantum dots; HER2; antibody; cellular imaging; breast cancer cell
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Tiwari, D.K.; Tanaka, S.-I.; Inouye, Y.; Yoshizawa, K.; Watanabe, T.M.; Jin, T. Synthesis and Characterization of Anti-HER2 Antibody Conjugated CdSe/CdZnS Quantum Dots for Fluorescence Imaging of Breast Cancer Cells. Sensors 2009, 9, 9332-9354.
Tiwari DK, Tanaka S-I, Inouye Y, Yoshizawa K, Watanabe TM, Jin T. Synthesis and Characterization of Anti-HER2 Antibody Conjugated CdSe/CdZnS Quantum Dots for Fluorescence Imaging of Breast Cancer Cells. Sensors. 2009; 9(11):9332-9354.
Tiwari, Dhermendra K.; Tanaka, Shin-Ichi; Inouye, Yasushi; Yoshizawa, Keiko; Watanabe, Tomonobu M.; Jin, Takashi. 2009. "Synthesis and Characterization of Anti-HER2 Antibody Conjugated CdSe/CdZnS Quantum Dots for Fluorescence Imaging of Breast Cancer Cells." Sensors 9, no. 11: 9332-9354.