Biodegradable hollow Co3S4@N-doped carbon as enhanced PTT/PDT agent for multimodal MR/thermal imaging and synergistic antitumor therapy

In this study, a nanoheterostructure was constructed by Co3S4 and N-doped carbon to reveal the improved photodynamic therapy (PDT) and photothermal therapy (PTT). Firstly, hollow Co3S4 nanosphere about 80 nm coated with N-doped carbon shell (CSC) was synthesized by using polyacrylonitrite nanospheres as sacrificial template as well as N source for N-doped carbon. The heterostructure reveals the higher photothermal conversion efficiency (57.5%) than that of pure hollow Co3S4 (46.7%) owing to the enhanced NIR (808 nm) absorption. In addition, the heterostructure also reveals the nearly two times reactive oxygen species (ROS) generation as pure Co3S4. The formation mechanism was investigated, revealing that it is the photo-exited electron and dissolved O2 to determine ROS generation and the effective segregation of photogenerated charge in heterostructure endows the great performance on PDT. In view of Co, the sample can be used as magnetic resonance imaging (MRI) contract (r2 = 6.2 mM−1s−1). What's more, CSCn also exhibit the considerable biodegradation ability, ascribing to the oxidation of S ion by O2 and Co3+ to induce the dissolvable sulfate. And the metabolite also can be eliminated from faeces within two weeks. After the loading of Dox, [email protected] can integrate of multi-model imaging (MRI and thermal imaging) and the synergy therapy (chemotherapy/PDT/PTT), making the potential theranostic application for anticancer.