Comparative Analysis of Silk Fibroin Membranes across Cross-Linking Methods: Processing and Characterization.

Area of Science:

• Biomaterials Science
• Ophthalmic Engineering
• Polymer Chemistry

Background:

• Silk fibroin (SF) membranes are suitable for ophthalmic applications due to their transparency and physical properties.
• Varied fabrication and characterization methods hinder direct comparison of SF membrane properties across studies.

Purpose of the Study:

• To fabricate and comprehensively characterize diverse silk fibroin membranes using physical cross-linking.
• To establish correlations between different physical and chemical properties of SF membranes.
• To provide a data compilation for informed selection of SF-based materials for specific applications.

Main Methods:

• Fabrication of 10 families of physically cross-linked SF membranes and one non-cross-linked control.
• Evaluation of transparency (84.5-95.3%), enzyme stability (24h-200 days), decomposition temperature (280-290°C), water uptake (40-60%), Young's modulus (8-30 MPa), and surface roughness (1.6-22.7 nm).
• Analysis of FTIR spectra for protein secondary structure and correlation with degradation rates.

Main Results:

• Transparency ranged from 84.5 to 95.3%.
• Enzyme stability varied significantly (24h to 200 days), correlating with protein secondary structure.
• A negative correlation was observed between water uptake and Young's modulus.
• Polyethylene glycol cross-linking resulted in higher roughness and faster degradation compared to alcohol cross-linking (methanol, ethanol, isopropanol).

Conclusions:

• The study provides extensive data on SF membrane properties, aiding material selection for ophthalmic applications.
• Cross-linking agents significantly influence SF membrane characteristics, including mechanical properties, stability, and degradation.
• Understanding structure-property relationships is crucial for tailoring SF membranes for specific biomedical needs.