Graphene-like Metal-Free 2D Nanosheets for Cancer Imaging and Theranostics.

The great success of graphene has driven the discovery and development of new 2D nanomaterials with different optical, electrical, and thermal properties. Compared with other graphene-like 2D nanomaterials, metal-free 2D nanomaterials hold great potential in biomedical applications since they exhibit much better biocompatibility and biosafety. We give an overview of some rapidly emerging graphene-like metal-free 2D nanomaterials including black phosphorus, hexagonal boron nitride, and graphitic carbon nitride, as well as 2D organic polymer-based nanomaterials, and highlight their impressive advances for bioimaging and cancer theranostics in recent years. The challenges and some thoughts on future perspectives in this field are also addressed.