Anisotropic chitosan micropatterning containing metformin functionalized calcium titanate (CaTiO3) nanoparticles for regulating dorsal root ganglion behavior

The surface topological structures of the artificial implants are conducive to induce orientation growth of nerve cells and promote nerve regeneration. However, their effect on long-distance extension of dorsal root ganglion (DRG) axons is still limited and needs further enhancement. In this study, an anisotropic chitosan (CS) micropatterning containing metformin (Me) functionalized CaTiO3 (CTO) nanoparticles (NPs) for regulating DRG behavior was fabricated by micro-molding and biomodification method. The physicochemical properties of CTO nanoparticles as a function of biomodification by poly-dopamine (PDA) and Me were monitored by Zeta (ζ) potential, Fourier Transform infrared spectroscopy (FTIR), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Spectroscopy (EDX) analysis, respectively. The morphology, structure, and wettability of the CS micropatterning were characterized. In addition, Atomic Force Microscope (AFM) was used to scan the topological membrane surface to explore its surface profile. The in vitro effect of the micropatterning on DRG axon behavior including morphology, length and orientation was evaluated. The results showed that PDA-modified CTO NPs could load Me effectively and showed considerable stability. The addition of Me functionalized CTO NPs obviously improved the hydrophilicity and roughness of the CS micropatterning. DRG culture showed that the axon extension on the topology followed the arrangement direction of the anisotropic microstructure. Compared with the pure CS micropatterning, the length of the axon extension on the surface of Me-PDA-CTO-CS was significantly improved about 61.1%, indicating an obvious axonal extension promotion effect. Therefore, it is concluded that the Me-PDA-CTO-CS could constrain the direction of axon extension while obviously promoting axon growth, which may be expected to provide a new strategy for repairing peripheral nerve injury (PNI).