Targeted Labeling And Biological Toxicity Of Quantum Dot Zn₃In₂S₆-CEA Fluorescent Probe To Colon Cancer Cell Line SW480

OBJECTIVE:To synthesize a novel Zn₃In₂S₆-CEA quantum dot fluorescence probe and use its special optical properties and its specific binding ability after antibody binding to the colon cancer cell line SW480 for fluorescence labeling and to further study its cytotoxicity.METHODS:Immunohistochemistry was used to characterize the CEA antigen on the cytoplasm and envelope of colon cancer cells.The Zn₃In₂S₆-CEA fluorescent probe was synthesized by combining water-soluble quantum dots Zn₃In₂S₆ with anti-CEA antibody.Immunofluorescence was used to detect the fluorescence labeling with the probe.The proliferation inhibition and apoptosis of colon cancer cells combined with the probe were detected with MTT assay and flow cytometry.RESULTS:The new Zn₃In₂S₆-CEA quantum dot fluorescent probe can effectively bind to the colon cancer cell line SW480 and intense fluorescence signaling can be observed on SW480 cell line under fluorescence microscope and confocal microscope,respectively.The cell inhibition rates of Zn₃In₂S₆-CEA and CuInS₂@Zn S-CEA probes at concentration of5%were 0.002262,0.101111,0.213652,0.301923,and-0.014933,0.111301,0.235352,and 0.303073 at 2 hrs,24 hrs,48 hrs,and 72 hrs,respectively.The Factorial analysis of varianceof the cytotoxicity assay showed that the inhibition rate of the Zn₃In₂S₆-CEA probe was significantly lower than that of the CuInS₂@ZnS-CEA probe?t=23.928,P<0.001?at 48 hrs,and there was no significant difference in cell inhibition rate between the two probes at the other time points,moreover the cell inhibition rate of the two probes was demonstrated in an increasing time-dependent manner with significant difference among different time points?F=4721.4001,P<0.0001?,The interaction between probes and time on cell inhibition was statistically significant?F=17.3660,P<0.0001?.The model fitting effect was quite satisfactory,R2=0.999.Flow cytometry results were basically consistent with the MTT assay results.CONCLUSIONS:CEA is highly expressed on the cell membrane and in the cytoplasm of colon cancer cell line SW480.The newly synthesized Zn₃In₂S₆-CEA probe was used and successfully labeled to the SW480 cells.After 48 hrs co-incubation of Zn₃In₂S₆-CEA probe or CuInS₂@ZnS-CEA probe with SW480 cells,the cytotoxicity of Zn₃In₂S₆-CEA probe on SW480 cells at labeling concentration was revealed to be lower than that of CuInS₂@ZnS-CEA probe.