PEGSSDA® allows researchers to quickly and gently dissolve HyStem® hydrogels non-enzymatically, thereby easily recovering cells or spheroids either grown on top or within the hydrogel. PEGSSDA contains two internal disulfide bonds which are rapidly reduced with small amounts of reducing agent (such as N-acetyl cysteine or glutathione), causing gel liquefaction. PEGSSDA is a pentablock PEGDA molecule composed of four PEG molecules (MW 2000 Da) and two interdigitated disulfide bonds. Only the external PEG molecules are acrylated. The final molecular weight is approximately 8500 Da1. Like PEGDA, PEGSSDA is a thiol-reactive crosslinker that covalently reacts with the thiol groups in Glycosil®, HyStem, Heprasil®, and Gelin-S® to form viscoelastic hydrogels. PEGSSDA is lyophilized in water.

Gelation
PEGSSDA is used to chemically crosslink Glycosil, HyStem, Heprasil, and Gelin-S. The gelation time ranges from as short as 5 minutes to as long as a couple of hours, depending upon the amount of PEGSSDA used and the concentration/dilution of the Glycosil, HyStem, Gelin-S and /or Heprasil. While we use thiol chemistry to crosslink our hydrogels, other researchers have used photoinitiators such as Darocur 1173. This process adds an extra level of complexity, as many photoinitiators are toxic to cells and the UV light used to crosslink the hydrogel can damage cells.