Materials for use in controlled release of water sol. macromol. drugs, such as proteins and polysaccharides, were developed, i.e. (1) a material that would be phase compatible with the water sol. drug; (2) a material that would induce a reduced inflammatory reaction by comparison with conventional materials; and (3) a material that could be formed in situ by a rapid light-induced crosslinking. The requirement for in situ polymn. mandates that the precursor be applied either neat or as an aq. soln., and that the precursor not cause undue cytotoxicity. For this reason, water-sol. precursors were developed which upon exposure to light in the presence of a suitable photoinitiator would crosslink to form a hydrogel. Polymn. in situ has some conceptual advantages over the use of preformed objects, in that (1) a conformal coating can be applied to an irregularly shaped tissue, and (2) a large object can be delivered, as a liq., through a very small port and assembled in situ. [on SciFinder (R)]