Cetuximab-conjugated iodine doped carbon dots as a dual fluorescent/CT probe for targeted imaging of lung cancer cells

Iodine doped carbon quantum dots (I-CQDs) have been synthesized by a facile one-pot hydrothermal method using citric acid and iohexol as precursors. The morphology and chemical structures of I-CQDs are investigated by TEM, XRD, XPS, and FTIR spectroscopy. The as-prepared I-CQDs exhibit excitation-dependent PL behavior with the emission quantum yield of 18%. The presence of iodine ions in I-CQDs is confirmed by XPS spectrum, which endows the composite with CT imaging performance. Thus, they could be used as efficient probes for fluorescence/CT bimodal imaging. To realize a precise diagnosis of tumor lesions, the surface of I-CQDs is conjugated with a targeting molecular (cetuximab) to afford I-CQDs-C225. The MTT assay against three kinds of human cell lines verifies the low cytotoxicity of I-CQDs-C225. The targeting ability of I-CQDs-C225 are evaluated in vitro using HCC827 cells (lung cancer cell line, over-expression of EGFR), H23 (lung cancer cell line, low expression of EGFR) and HLF cells (lung normal cell line, low expression of EGFR) via a confocal laser scanning microscope. The results show that HCC827 cells exhibited strong fluorescence, indicating the cetuximab-conjugated I-CQDs could target specifically the cancer cells with over-expression of EGFR via EGFR mediated endocytosis.