Preparation of Fetal Bovine Serum–Copper Phosphate Hybrid Particles under Cell Culture Conditions for Cancer Cell Treatment

Fetal bovine serum (FBS) particles, which mainly consist of bovine serum albumin, have the potential for biological and medical applications as drug carriers. The coacervation of albumin is a common technique for preparing albumin-based particles. The replacement of salt with novel metal salts such as Cu is an affordable way to embed the metal ion in the albumin-based particles. Further, increased Cu distribution is prevalent in many cancers. Here, we prepared adhesive cell-like FBS–copper phosphate hybrid particles [FBS-Cu3(PO4)2], which exhibited toxicity toward cancer cells, with a narrow size distribution under cell culture conditions for preventing tumor progression. FBS-Cu3(PO4)2 showed peroxidase-like activity. In addition, FBS-Cu3(PO4)2 was successfully loaded with rhodamine B and conjugated with fluorescein isothiocyanate as models of drugs by coincubation. Thus, we designed a simple preparation method for optimizing FBS-Cu3(PO4)2 synthesis under cell culture conditions. FBS-Cu3(PO4)2 has significant potential as an efficient reactive oxygen species generator and drug-delivery agent against cancer cells. Furthermore, the RhoB-loaded FBS-Cu3(PO4)2 successfully interacted with 4T1 mouse mammary tumor cells and were confirmed to exhibit toxicity.