The CQDs were conjugated with a target molecule (Cetuximab) to facilitate CQDs-C225 labeling of HCC827 (lung cancer cell line, epidermal growth factor receptor (EGFR) over expression), H23 (lung cancer cell line, EGFR under expression), and HLF (normal lung cell line, EGFR under expression) cells. The gene discussed is EGFR; the disease is lung carcinoma.