Constructing a MXene/PDA/PLLA conduit with strong interface binding and three-dimensional continuous conductive network for promoting cell nerve differentiation

Conductive polymer composite scaffold displayed great advantages in nerve repair due to it could highly simulate the electrical microenvironment of natural tissues. However, the poor interfacial adhesion and the discrete distribution of conductive fillers in polymer matrix weaken its conductivity. Herein, Polydopamine (PDA) was grown in situ on PLLA microspheres, and then loaded with MXene nanosheets. Subsequently, a conductive MXene/PDA/PLLA conduit was fabricated by laser additive manufacture. During this processing, a three-dimensional continuous conductive network was constructed on the conduit utilizing its shearing-free properties. Meanwhile, PDA could form covalent and hydrogen bonds with MXene and PLLA through catechol, amino and imino groups, enhancing their interfacial compatibility. Additionally, PDA could generate photothermal for antibacterial under near-infrared radiation. DFT calculations proved the existence of favorable interfacial interactions between PDA and MXene and PLLA. Results showed that MXene was uniformly wrapped around the PLLA, forming a three-dimensional continuous conductive network in the conduit. At 7.5 wt% MXene, the permeation threshold and conductivity reach 1.81 % and 4.8 S/m, respectively. The enhanced current promoted cell nerve differentiation, as evidenced by a 2.4-fold upregulation of Nestin and a 4.3-fold increase in Ca 2 + influx. Besides, the conduit could effectively kill S. aureus and E. coli due to its excellent photothermal effect.