Functional phosphorene: Burgeoning generation, two-dimensional nanotherapeutic platform for oncotherapy

Due to the high surface-area, adjustable bandgap width, inherent non-toxic biodegradability, infrared-light responsiveness, intrinsic fluorescence and photoacoustic properties, etc., a mono-elemental material–phosphorene, also referred to as black phosphorus (BP) in the form of mono/few layers, has emerged as one of the most popular alternatives among the two-dimensional (2D) nanomaterials in biomedicine. Although phosphorene appears to be promising, the exploration of phosphorene is still in the initial stage, compared with other graphene analogs that have been investigated intensively. So far, the main defect hinders biomedical application of bare phosphorene is the poor ambient stability in existence of water and air, not to mention interactions with plasma proteins in vivo. Based on this case, the recent progresses on the fabrication (top-down and bottom-up methods), passivation strategies from physical, chemical, and toxicological aspects of phosphorene are summarized. The representative oncotherapy based on phosphorene, ranging from mono-phototherapy to theranostic (sonodynamic therapy, radiotherapy, chemodynamic therapy, chemotherapy, genetherapy, immunotherapy, synergistic therapy and fluorescence/photoacoustic-based bio-imaging) are also summarized in details. The key obstacles and future trends of phosphorene are proposed for conceiving/engineering novel phosphorene-based nanoplatforms for multidisciplinary biomedical applications.