biodistribution of kinetically stable PtL nanospheres that show anti-cancer activity.

There is an increasing interest in the application of metal-organic cages (MOCs) in a biomedicinal context, as they can offer non-classical distribution in organisms compared to molecular substrates, while revealing novel cytotoxicity mechanisms. Unfortunately, many MOCs are not sufficiently stable under conditions, making it difficult to study their structure-activity relationships in living cells. As such, it is currently unclear whether MOC cytotoxicity stems from supramolecular features or their decomposition products. Herein, we describe the toxicity and photophysical properties of highly-stable rhodamine functionalized platinum-based PtL nanospheres as well as their building blocks under and conditions. We show that in both zebrafish and human cancer cell lines, the PtL nanospheres demonstrate reduced cytotoxicity and altered biodistribution within the body of zebrafish embryos compared to the building blocks. We anticipate that the composition-dependent biodistribution of PtL spheres together with their cytotoxic and photophysical properties provides the fundament for MOC application in cancer therapy.