Recent advances in mapping the sub-cellular distribution of metal-based anticancer drugs

There are increasing reports of novel metal-based chemotherapeutics that have either improved cancer cell selectivity, or alternative mechanisms of action, to existing anticancer drugs, and techniques are required for determining their sub-cellular molecular targets. Imaging methods offer many distinct advantages over destructive fractionation techniques, including the preservation of useful morphological information; however, mapping the intracellular distribution of metal ions inside tumour cells still remains challenging. Recent advances in three modes of imaging are discussed in this review, with a particular focus on the application to metal-based cancer chemotherapy fluorescence microscopy, electron microscopy (including energy-filtered transmission electron microscopy (EFTEM)), and a new technique, Nano-scale secondary ion mass spectrometry (NanoSIMS).