In Vitro-In Vivo Correlation for the Degradation of Tetra-PEG Hydrogel Microspheres with Tunable β-Eliminative Crosslink Cleavage Rates

Figure 3

Formation of Tetra-PEG hydrogels with cleavable crosslinks connected to the α- or ε-amine of a lysine residue that forms part of the crosslink. The R groups in hydrogels 7 and 8 show the position where a cleavable linker can be attached to tether a releasable drug or, in the case of this work, where fluorescein has been attached to facilitate detection of gel components by fluorescence upon gel degradation.