Platinum as both a drug and its modulator - Do platinum nanoparticles influence cisplatin activity?

Breast cancer was the most frequent cause of cancer death in females in 2022. Despite the development of personalized therapies, chemotherapy frequently remains the only available treatment method. However, the administration of classic antineoplastic drugs, like cisplatin (CDDP), often causes severe side effects and may lead to drug resistance making the therapy inefficient. Therefore, there is a great need for new, effective treatment regimens development. For this reason, we applied platinum nanoparticles (PtNPs) to verify if they can influence the CDDP activity with particular emphasis on the differences due to nanoparticles' sizes. We employed a broad spectrum of physicochemical methods, including Dynamic Light Scattering, Atomic Force Microscopy, Isothermal Titration Calorimetry, Fourier Transform Infrared Spectroscopy, and Near Infrared Spectroscopy and also Differential Scanning Calorimetry, to characterize the possible interactions between nanoparticles and CDDP. Moreover, the impact of PtNPs on CDDP biological activity was investigated using the Ames mutagenicity test on Salmonella enterica serovar Typhimurium TA102 and MTT assay on two breast cancer cell lines MDA-MB-231 and SKBR3. The obtained results revealed PtNPs direct interactions with CDDP dependent on the nanoparticles' size. Despite the lack of explicit confirmation of PtNPs aggregation by AFM imaging and DLS, further physicochemical methods indicated structural changes between nanoparticles alone and PtNPs-CDDP mixtures. Moreover, the biological assays confirmed that PtNPs decrease CDDP mutagenicity and also slightly increase its cytotoxicity on the chosen cell lines. The latter effects are ambiguous, nevertheless, provide a valuable basis for further research.