An improved barrier or drug delivery system which is highly adherent to the surface to which it is applied is disclosed, along with methods for making the barrier. The barrier can be prepared by staining tissue with a photoinitiator, applying a solution containing a polymerizable barrier material solution and a photoinitiator to the tissue, and polymerizing the polymer solution on exposure to light. The resulting polymer adheres strongly to the tissue surface, and also forms a gel in the rest of the applied volume. The polymerizable barrier materials are highly useful for sealing tissue surfaces and junctions against leaks of fluids. The method can be used to adhere preformed barriers to tissue or other surfaces, or to adhere tissue surfaces to each other. Tissue surfaces can be adhered to each other to repair wounds. In addition to photochemical initiators, non-photochemical initiators and combinations of chemical initiators and photochemical initiators can be used.