Synthesis of CdTe quantum dot-conjugated CC49 and their application for in vitro imaging of gastric adenocarcinoma cells

Abstract

The purpose of this experiment was to investigate the visible imaging of gastric adenocarcinoma cells in vitro by targeting tumor-associated glycoprotein 72 (TAG-72) with near-infrared quantum dots (QDs). QDs with an emission wavelength of about 550 to 780 nm were conjugated to CC49 monoclonal antibodies against TAG-72, resulting in a probe named as CC49-QDs. A gastric adenocarcinoma cell line (MGC80-3) expressing high levels of TAG-72 was cultured for fluorescence imaging, and a gastric epithelial cell line (GES-1) was used for the negative control group. Transmission electron microscopy indicated that the average diameter of CC49-QDs was 0.2 nm higher compared with that of the primary QDs. Also, fluorescence spectrum analysis indicated that the CC49-QDs did not have different optical properties compared to the primary QDs. Immunohistochemical examination and in vitro fluorescence imaging of the tumors showed that the CC49-QDs probe could bind TAG-72 expressed on MGC80-3 cells.

Figure 1

In vitro labeling of MGC80-3 cells with CC49-QDs Ab probe and primary QDs. (A1/B1/C1/D1) The cell nucleus was stained with DAPI. (A2) MGC80-3 cells labeled with QDs. (B2) MGC80-3 cells labeled with CC49-QDs. (C2) MGC80-3 cells labeled with CC49-QDs after blocked with free CC49. (D2) MGC80-3 cells labeled with fluorescent secondary antibody. A3/B3/C3/D3 were merged with A1 and A2, B1 and B2, C1 and C2, D1 and D2, respectively.

Figure 2

In vitro labeling of GES-1 cells with CC49-QDs Ab probe and primary QDs. (E1/F1/G1/H1) The cell nucleus was stained with DAPI. (E2) GES-1 cells labeled with QDs. (F2) GES-1 cells labeled with CC49-QDs. (G2) GES-1 cells labeled with CC49-QDs after blocked with free CC49. (H2) GES-1 cells labeled with fluorescent secondary antibody. E3/F3/G3/H3 were merged with E1 and E2, F1 and F2, G1 and G2, H1 and H2, respectively.

Figure 3

Powder X-ray diffraction pattern of hydrothermally prepared CdTe QDs (λ_cm = 600 nm). The line spectra show the cubic CdTe and CdS reflections with their relative intensities.

Figure 4

Physical properties of near-infrared quantum dots. (A) Transmission electron microscope image of QDs. (B) Transmission electron microscope image of CC49-QDs.

Figure 5

Spectrum analysis. (A) The primary CdTe QD spectrum analysis curve. (B) The CC49-QDs spectrum analysis curve.

Figure 6

HPLC elution curves for (A) CC49-QDs and (B) free CC49. The retention times of CC49-QDs and free CC49 were about 6.91 and 9.65 min, respectively.

Figure 7

Immunohistochemical examination of TAG-72 expression. Experimental group: the SP immunohistochemical staining of MGC80-3 (A) and GES-1 (B). Control group (the primary antibody was replaced by PBS): the SP immunohistochemical staining of MGC80-3 (C) and GES-1 (D).