2D nanostructures beyond graphene: preparation, biocompatibility and their biodegradation behaviors

Owing to their special physicochemical characteristics, much attention has been paid to the fabrication of two-dimensional (2D) nanomaterials as therapeutics for nanomedicine in recent years. These fascinating physicochemical properties alongside with their diverse biomedical applications drive us to give a reviewing of the present endeavors of interest in these 2D nanomaterials. In this review, the up-to-date research proceedings of the preparation, biocompatibility and biodegradation behaviors of 2D nanomaterials including transition-metal dichalcogenides (TMDs), transition metal oxides (TMOs), black phosphorus nanosheets (BP), metal-organic framework (MOF), 2D boron nitride (BN), layered double hydroxide (LDH), 2D nanoscale metals, and other kinds of 2D nanomaterials were introduced. The in vitro and in vivo bio-compatibility, including their degradation assessments from the aspects of redox reaction, enzymatic, pH, and cell environment, etc., of the above categories of 2D nanomaterials were detailedly discussed. Finally, the prospects and challenges of the development of 2D nanomaterials aiming for biomedical applications are summarized.