Synthesis, Characterization, and Biological Study of Carboxyl- and Amino-Rich g-C₃N₄ Nanosheets by Different Processing Routes.

Graphitic-phase carbon nitride (g-C₃N₄) is a graphene analogue, which has attracted much attention for its unique physicochemical properties. The bulk g-C₃N₄ is often fragmented and ionized to nanosheets, obtaining improved performance or confer novel properties. It is reported that g-C₃N₄ nanosheets using different processing methods can be modified with different functional groups, resulting in different electrical characteristics. However, the surface charge of g-C₃N₄ nanosheets is seldom mentioned as a factor influencing their biological applications. In our present study, we prepared two kinds of uniformly dispersed g-C₃N₄ nanosheets of high quality, the carboxyl- and amino-rich g-C₃N₄ nanosheets. Although both the carboxyl- and amino-rich g-C₃N₄ nanosheets displayed good biocompatibility in vitro and in vivo , however, they are at very different levels of surface charge, which are relative to different cellular uptake, penetration mechanism and lysosome escape ability of the nanosheets.