Protein papers from microfibrillated silk for biomedical membrane applications

Microfibrillated silk (MFS) is an emerging class of silk materials produced by directly exfoliating silk fibres, offering a top-down alternative to traditional regenerated silk processing methods. They have the potential to be used as biomaterials, particularly in tissue engineering and regenerative medicine. This study used a unique tuneable top-down approach to produce different MFS suspensions. These were then fabricated into protein papers using two scalable methods, casting and vacuum filtration, to examine how processing and fabrication together influenced the final material properties and associated cellular responses. MFS suspensions were prepared under three processing levels using mechanical processing alone or combined with acid pre-treatment with each level yielding increasingly finer fibrils. The level of fibrillation significantly affected fibre morphology and mechanical strength, while the fabrication method mainly influenced surface roughness and bilayer characteristics. Papers made with mechanical processing alone had the highest strength. Cast papers revealed a surface difference, with a rough top surface and smooth bottom surface, while vacuum-filtered papers had uniform roughness on both sides. These surface differences, along with the degree of fibrillation, impacted cell attachment and organization, with cast papers from acid-pretreated and shear-homogenised MFS showing the best biological outcomes. Controlling MFS processing and assembly techniques to form papers enables the design of silk-based materials tailored for various biomedical applications.