Degumming Control as a Strategy to Modulate Structure and Cytocompatibility of Silk Fibroin Membranes for Regenerative Medicine Applications

Abstract

Bombyx mori silk fibroin is one of the most promising biomaterials for tissue engineering and regenerative medicine due to its biocompatibility, mechanical performance, and versatility for processing into three-dimensional structures. However, the degumming conditions employed to remove sericin can significantly alter fibroin molecular organization and consequently affect the biological performance of the resulting scaffolds. Understanding the relationship between processing parameters, structural organization, and cellular response is essential for the rational design of biomaterials intended for tissue regeneration.

OBJECTIVE

To evaluate the effect of different degumming conditions on the structural, mechanical, and biological properties of electrospun silk fibroin membranes intended for regenerative medicine applications.

METHODOLOGY

Bombyx mori cocoons were subjected to different degumming treatments using sodium carbonate (Na₂CO₃), sodium lauryl ether sulfate (SLES), and varying reaction times. Sericin removal efficiency was determined through mass loss analysis. Regenerated silk fibroin was subsequently processed by electrospinning to fabricate nanofibrous membranes. Structural characterization included scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), solid-state 13C nuclear magnetic resonance (13C-NMR), X-ray diffraction (XRD), optical profilometry, and microindentation testing. Cytocompatibility was assessed using MTT and Live/Dead assays with human dermal fibroblasts.

RESULTS

Alkaline degumming treatments achieved sericin removal efficiencies greater than 90%, promoting increased β-sheet exposure and higher crystallinity compared with surfactant-based treatments alone. Electrospun membranes exhibited fiber diameters ranging from 0.37 to 1.38 µm and crystallinity values of up to 38%. Biological assays demonstrated a concentration-dependent response. Membranes derived from Na₂CO₃-treated fibroin maintained cell viabilities above 80%, whereas membranes obtained from surfactant-only treatments showed a significant reduction in cellular metabolic activity. Membranes E5, E6, and E13 preserved the characteristic elongated fibroblast morphology, with E5 showing the most favorable combination of surface roughness, intermediate mechanical properties, and cytocompatibility. No intrinsic antibacterial activity was observed against Staphylococcus aureus or Pseudomonas aeruginosa.

CONCLUSIONS

Degumming is a critical process parameter that regulates the structural organization and biological performance of electrospun silk fibroin membranes. Alkaline treatments promote efficient sericin removal, increase crystallinity, and enhance the early cellular response. Among the evaluated materials, membrane E5 exhibited the most favorable structural, mechanical, and biological characteristics, making it a promising candidate for the development of scaffolds for tissue engineering and regenerative medicine applications. These findings highlight the importance of degumming as a structure-controlling strategy for the design of reproducible and biologically safe silk-based biomaterials.