Methods and apparatus of forming in situ tissue adherent barriers are provided using a sprayer capable of applying two or more viscous crosslinkable components to tissue. The sprayer comprises separate spray nozzles for each of two or more crosslinkable solutions, with each nozzle surrounded by an annular gas flow outlet. Crosslinkable solutions are stored in separate compartments and communicated under pressure to the spray nozzles. In the presence of gas flow through the annular gas flow outlets, the crosslinkable solutions are atomized and mixed in the gas flow to form a spray. Multi-component hydrogel systems suitable for use with the inventive methods and apparatus are also described.