t-PA was loaded into the gels durin

t-PA was loaded into the gels during gel formation. The loading and release of t-PA were quantified using radiolabeled t-PA. Freshly prepared hydrogels were thoroughly washed to remove loosely bound t-PA prior to loading measurements. The loading data are shown in Fig. S5 (ESI†). It is seen that t-PA loading increasedwithincreasingDCL.Loadingalsoincreasedmarkedly with increasing concentration of t-PA in the hydrogel preparation, and in this case loading increased more strongly with increasing DCL. These phenomena may be due to the fact that the hydrogels of high crosslinking degree have smaller pores and a tighter network and thus may retain more t-PA following washing.