synthetic polymers, or collagen, are normally used. scientists are also exploring the use of silk. these are cartilage generating cells growing on a scaffold made of spider silk. this is a sample of a scaffold made from the silk of dr. han's silkworms. because it's also fluorescent, it would be easy to monitor the scaffold and actually see the cells growing. >> dr. han and his team have spent three years working out how to integrate color into the core of silk filament, called the fibroin, so it doesn't wash away. this is the silkworm's normal feed, a thick green paste of mulberry powder and water, to which the researchers added a special chemical dye. then they fed it to the worms, the larvae of the silk moth, which changed color within several hours. the incorporation of dye molecules while the silk was being synthesized in the worm's silk glands ensured that the dye in the silk would combine at a molecular level when the silkworm began to spin its cocoon. >> in the future, it's hoped the silk used to make these scaffolds will have not just color incorporated into it, but propert