Influences of protein-corona on stability and aggregation kinetics of Ti3C2Tx nanosheets in aquatic environment

Proteins existed in aquatic environments strongly influence the transport, fate of nanomaterials due to the formation of protein-corona surrounding nanomaterials. To date, how do proteins affect the aggregation behaviors of MXene, a new family of two-dimensional materials, in aquatic environment remains unknown. Here the aggregation kinetics of MXene Ti 3 C 2 T x nanosheets in various electrolytes (NaCl, CaCl 2 and Na 2 SO 4 ) was investigated by time-resolved dynamic light scattering in absence or presence of bovine serum albumin (BSA). Results showed that BSA affected the aggregation of Ti 3 C 2 T x in a concentration-dependent manner. Addition of 3 mg/L BSA decreased the critical coagulation concentrations (CCCs) of Ti 3 C 2 T x about 1.6–2.1 times, showing obvious destabilization effect; while BSA greater than 30 mg/L created a high-protein environment covering Ti 3 C 2 T x , producing high spatial repulsion and enhancing the dispersibility of Ti 3 C 2 T x . Ca 2+ ions have greater effect on the aggregation of Ti 3 C 2 T x due to the larger surface charge and bridging effect. The interaction between Ti 3 C 2 T x and BSA followed Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, and mainly attributed to hydrogen bonding and van der Waals forces , while positively charged lysine and arginine in BSA might attract onto Ti 3 C 2 T x through electrostatic attraction. The interaction decreased the content of α -helix structure in BSA from 74.7% to 53.1%. Ti 3 C 2 T x easily suffered from aggregation and their long-distance transport seemed impossible in synthetic or natural waters. The present findings provided new insights for understanding the transfer and fate of this nanomaterial in aquatic environments.