Protective effects of silk fibroin against 6-OHDA in SH-SY5Y human neuroblastoma cells and comparative study with its release from gelatin films

In this study, we analyzed the neuroprotective action of silk fibroin (SF) regenerated with calcium chloride (CaCl₂), distinguishing the effects of CaCl₂ and SF, and subsequently fabricating a neuroprotective hybrid material based on SF gelatin film. Cytotoxicity induced by 6-hydroxydopamine (6-OHDA) on the human neuroblastoma SH-SY5Y cell line showed that SF had a significant shielding power against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in SH-SY5Y neuroblastoma cells, as assessed by the CCK-8 assay, cell imaging and cell cycle using flow cytometer. Specifically, the concurrent treatment with SF and 6-OHDA produced a marked neuroprotective effect. Circular dichroism analysis suggested the formation of silk III because of the interaction between the secondary structures of SF and 6-OHDA. Raman analysis was also employed to assess the impact of SF and CaCl₂ on cellular metabolism, indicating the combined administration of fibroin and 6-OHDA as more effective than the use of CaCl₂ alone. Subsequently, we synthesized a silk/gelatin-based film, demonstrated its ability to release SF, and confirmed its capacity to protect SH-SY5Y neuroblastoma cells.