Targeting breast cancer cells with a CuInS2/ZnS quantum dot-labeled Ki-67 bioprobe

The aim of the present study was to develop a water-soluble biomarker for the detection of breast cancer using quantum dots (QDs) conjugated to Ki‑67, a nuclear protein associated with the cell cycle. Ki‑67 is also a marker of cell proliferation, with expression levels categorizing good and poor prognosis in invasive breast cancer. Ki‑67 is a clinically used biomarker for breast cancer diagnosis, treatment and prognosis. Owing to the optical and chemical advantages of QDs, QD‑based nanotechnology may aid the construction of a biomedical imaging platform for the study of cancer cell behavior. In the present study, a biomarker was prepared by employing the water‑soluble CuInS2/ZnS QDs conjugated to an anti‑Ki‑67 monoclonal antibody to detect Ki‑67 expression in breast cancer. The QDs, which were hydrophobic and coated with octadecylamine, were encapsulated with an amphiphilic biocompatible centipede‑like polymer, and then conjugated to anti‑Ki‑67 monoclonal antibodies (QD‑Ki‑67 probes). The QD‑Ki‑67 probes retained the original optical properties of the unadorned QDs and did not exhibit distinct toxic side effects in in vitro cytotoxicity experiments. Therefore, this CuInS2/ZnS QD‑labeled bioprobe, with a high quantum yield and low cytotoxicity, is a promising candidate for bioimaging and may be used as a cell label.