reu1 highlight 8.09 img a Posted on October 1, 2015October 1, 2015 by Felice Macera Next → Worm gels are composed of, co-block polymer worms, 20-40 nm diameter, embedded in a polyacrylamide (PA) hydrogel. The worms mechanically mimic collagen fibers, and the PA holds water like the ground substance in articular cartilage.