Fig. 3: Design, physical and chemical characterization, and biocompatibility of MF-NGC.

a Microstructure of MF-NGC. TEM image displayed a core/shell structure of CS/PEDOT NFs, and SEM images showed oriented fiber morphology of inner CS/PEDOT conducting layer and nanoporous structure of outer PCL supporting layer, respectively. b XRD of PEDOT: PSS membrane (orange line), CS/PEDOT: PSS (blue line), and CS/PEDOT NFs (green line). PEDOT: PSS membrane and CS/PEDOT: PSS showed amorphous structure, while the CS/PEDOT NFs displayed the obvious characteristics peaks of linear PEDOT molecular chain. c Compared with conventional hybrid biomaterials^{51,52,53,54,55,56,57,58,59,60,61}, our MF-NGC reached the highest conductivity using a trace amount of PEDOT (0.8 wt%). d Cyclic voltammogram curve of the MF-NGC showed excellent electrochemical stability under different scan rates, the inset was photographs of MF-NGC connection with a cable and a LED bulb during bending. e Surgical images of MF-NGC were sutured at both ends of a 15 mm defected sciatic nerve, bar: 5 mm. Inset was an image of Small animal x-rays. f TNF-α (green) and CD68 (red) immunofluorescent staining of nerve tissue around MF-NGC at different time points. g Relative TNF-α expression level measured from CD68 immunofluorescent staining. h Vpp, Ipp, and electric field distribution (calculated from FEA) of output Bio-iES signals driven by respiratory motion under different physiological states of SD rats. i Frequency of Bio-iES signals and respiratory movement recorded by a vital signs monitor. j Vpp and Ipp of output Bio-iES signals recorded in 14 weeks. Data are expressed as mean values ±S.D. (n = 5, *p < 0.05, **p < 0.01, ***p < 0.001).