NF‐GS scaffold preparation

The methods for the preparation of NF‐GS scaffolds have been described in detail in our previous study.12 Briefly, sterile gelatin sponge (GS) scaffolds were tailored into a “D” shape tube with a diameter of 2 mm and a length of 4 mm, submerged in NT‐3/fibroin (NF) particle solution completely and wrapped up with poly‐lactic‐co‐glycolicacid (PLGA) tubes. The scaffolds used in the present experiment comprised three groups in vitro; (1) GS coated with NT‐3/fibroin complex group [the NF‐GS group, Fig. ​Fig.1(A)],1(A)], (2) GS coated with fibroin group [the F‐GS group, Fig. ​Fig.1(B)]1(B)] and (3) GS without NT‐3 and/or fibroin coating [the GS group, Fig. ​Fig.1(C)],1(C)], and two groups in vivo; (1) GS coated with NT‐3/fibroin complex group (the NF‐GS group), and (2) GS coated with fibroin group (the F‐GS group or the control group).

Structural features and bioactivity of the scaffold. Showing NF‐GS (A), F‐GS (B), and GS (C) with porous microstructure at low magnification. D: Showing NT‐3 positive sites (red arrows) on NF‐GS were labeled by gold enhanced nanogold particles. NT‐3 positive sites are absent in F‐GS (E) and GS (F). G: Showing NT‐3 positive gold enhanced nanogold particles (red arrows) on the surface of random coil structure of NF‐GS. (g) Showing NT‐3 positive sites on the surface of NF‐GS by immunofluorescence staining. NT‐3 positive particles are absent on the surface of random coil structure of F‐GS (H) and GS (I). NT‐3 positive sites are absent on the surface of F‐GS (h) and GS (i) by immunofluorescence staining. J: Cumulative release profile of bioactive NT‐3 from NF‐GS of different fibroin concentrations up to 28 d. n = 5, *p < 0.05, ^# p < 0.05, ^@ p < 0.05. Scale bars = 500 μm in (A–C); 125 μm in (a–c); 500 nm in (D–I); 20 μm in (g–i).