Recent progress of black phosphorus and its emerging multifunction applications in biomedicine

Abstract

Two-dimensional black phosphorus (BP) has layer-dependent band gap, high specific surface area, moderate carrier mobility, excellent photothermal effect, inherent photoacoustic properties, excellent biodegradability and biocompatibility, making it an ideal option for applications in biomedicine such as photothermal therapy, disease diagnosis, biological imaging and so on. Despite of these advantages, the two-dimensional BP has its own obstacle limiting its practical application, such as its instability, and there is no practical method for synthetization of large size BP flakes for industrial application. This review firstly introduces interesting properties of BP such as its biocompatibility, biodegradability, anisotropy, moderate carrier mobility and so on. Then summarizes the preparation methods of two-dimensional BP: non-liquid phase methods (e.g. mechanical peeling and chemical vapor deposition) and liquid phase methods (e.g. liquid-phase exfoliation and wet chemistry methods). The application of BP in the biomedical field such as photoacoustic imaging, fluorescence imaging, photothermal imaging, circulating tumor DNA detection, cancer treatment and treatment of neurodegenerative diseases are introduced later. Then we discussed the current problems of BP and methods to enhance the stability of BP including encapsulation, functionalization, liquid phase environmental protection and doping. Finally, some future trends in the research of two-dimensional BP are envisaged. It is believed that two-dimensional BP will have a broad application prospect in various fields especially in biomedicine due to its biocompatibility and biodegradability.