Learning from human metabolism for nanomedicine: a convertible bismuth-agent for tumour-selective theranostics.

Tumour-selective theranostic agents have attracted considerable interest over the past decade in oncology owing to their extraordinary anticancer efficacy. However, it still remains a challenge to develop theranostic agents balancing biocompatibility, multidimensional theranostics, tumour-selectivity, and simple components. Inspired by the metabolic pathways of exogenous sodium selenite against selenium-deficient diseases, reported here is the first convertible bismuth-based agent for tumour-selective theranostic functionalities. The specifically overexpressed substances in tumour tissue enable it to act as a natural reactor for the conversion from bismuth selenite to bismuth selenide, activating the theranostic functionalities specifically in tumour tissues. The converted product exhibits excellent multidimensional imaging-guided therapy. This study not only demonstrates a simple agent with both biocompatibility and sophisticated tumour-selective theranostic functionalities, but also pioneers a new approach from emulating nature towards oncological theranostic applications.