Evaluation of Internal Distribution and Extracellular Action of the Cell via TOF-SIMS

Cisplatin is one of the most popular and traditional platinum-based anti-cancer drugs. Additionally, it is known for its effect on different types of cancers. To clarify the reaction mechanism of anti-cancer drugs in a cell, the visualization of drugs in a single cell is required. In this study, we investigated a secondary ion species obtained from cisplatin, which was bounded to the nucleus in a cell and its intensity. PtCl₂^- was mainly detected via SIMS during an analysis of pure cisplatin reagent. In contrast, a high-intensity signal for PtCN^- was detected from cultured cells that were administered cisplatin. However, this signal was not detected from cisplatin in the reagent state. Chlorine in the cisplatin structure is replaced with water when it is combined with the cell nucleus. Therefore, PtCN^- was mainly detected from the intracellular region because the structure was changed by cisplatin binding to the nucleus and which exhibits anti-cancer activity. The results showed that the cisplatin selectively combined with the nucleus. Through TOF-SIMS, we achieved a visual distribution of the cisplatin intracellular nucleus.