You can control the swelling ratio of gelatin hydrogels by controlling the cross-linking degree. The higher the cross-linking degree the tighter the polymeric network the lower the swelling capacity. You can calculate the number of reactive functional groups of gelatin, and try to use an equi molar amount of the functional groups from the cross-linker counterpart. The more balanced the stoichiometric ratio of the reaction, the higher the conversion degree and the higher the cross-linking  density.

I hope this could help you,

Regards,

Irini Gerges,Ph.D

Dear Dr. Irini,

Thank you for the suggestion. Do you have any other idea apart from crosslinking. Since my objective is to control swelling ratio as well as to increase the hyrophobicity of the gels

An idea to increase the hydrophobicity can be chemical modification of gelatin by hydrophobic biodegradable polymers, such as PLGA. You may be inspired by the chemichal approach illustrated in the paper linked below.

Bests,

Irini G.

http://onlinelibrary.wiley.com/doi/10.1002/jbm.b.31394/abstract;jsessionid=4FD4D492FB8BD2DEB7545343DFC33569.f02t02?userIsAuthenticated=false&deniedAccessCustomisedMessage=

Dear Dr.Irini,

Thank you very much. I will go into them an find the possible solution