What is the difference between Biosilk and Biosilk 521?

Biosilk 521 is Biosilk functionalized with Biolaminin 521. Biolaminin 521 (human recombinant laminin 521) is a key cell adhesion protein of the natural stem cell niche, providing the Biosilk 521 material with unique, functional properties that are ideal for integration, proliferation, and subsequent lineage-specific differentiation of human pluripotent stem cells in a 3D format.