Hydrogels Formed by Multiple Peptide Ligation Reactions To Fasten Corneal Transplants WathierMichel JohnsonC. Starck KimTerry GrinstaffMark W. 2006 A stable cross-linked hydrogel was formed under mild aqueous conditions using pseudoproline peptide ligation chemistry. A cysteine-terminated lysine dendron containing four cysteines and a PEG macromolecule modified with terminal ester aldehydes were prepared. Upon mixing, the two macromers gave a stable hydrogel. This hydrogel along with sutures was used to successfully secure a corneal transplant in vitro.