Herceptin-conjugated magnetic polystyrene-Agsbox nanoparticles as a theranostic agent for breast cancer

Breast cancer is a malignant tumor, which has derived from cells of the breast. Further, a relatively rapid metastasis, and resistance development against all the conventional drug combinations are major clinical issues in breast cancer patients as well as limitations like toxicity, genetic mutation, and metastasis make difficult the use of conventional therapy methods such as chemotherapy, radiotherapy, and local surgery. Therefore, considering the urgent needs, and high death rate in breast cancer cases, the development of new diagnosis and treatment regimens which diagnosed at the early stage and protected normal tissues required for clinical applications. Recently, the combination of tumor diagnosis and treatment within a single platform is a novel perspective, and magnetic nanoparticles are potential candidate owing to their low toxic effect, biocompatibility, biological degradability, superior magnetic properties, and targeting ability to overcome the problems of conventional diagnosis and therapy techniques. Considering these restrictions and requirements, the goal of this research was to investigate the potential of an innovative theranostic agent, which is soybean oil-based polystyrene (PS)-g-soybean oil graft copolymer containing AgNPs (PS-Agsbox) for treatment and MRI-based diagnosis of cancer. Herein, we designed targeted magnetic PS-Agsbox nanoparticles carrying thymoquinone (TQ) that is known for its anticancer potential against breast cancer, and herceptin (HER), which is to bind to the HER2 receptor protein on the surface of HER2-positive tumor cells, and acts by blocking the effects of it. We have successfully demonstrated selective binding, effective uptake of HER-conjugated magnetic PS-Agsbox nanoparticles into MDA-MB-231 (human breast carcinoma cells, a HER2-underexpressing cell line) and SKBR-3 (human breast cancer cells, a HER2-overexpressing breast cancer cell line) cell lines while no effect against L929 (mouse fibroblast cell line). Moreover, the magnetic resonance (MRI) properties of HER-conjugated magnetic PS-Agsbox nanoparticles were also confirmed.