Dear Mohammad,

The best methods to sterilize sodium alginate solutions are:

1-Using Ethylene Oxide

2-Gamma Radiation

3-UV radiation may be also sufficient.

For more on the first two methods, please read the publication contained in the following link:

http://pubs.acs.org/doi/pdf/10.1021/bp00001a008

Alternatively, you can purchase a sterile sodium alginate solution (PRONOVA Sterile Alginates).

http://www.novamatrix.biz/Products/PRONOVASterileAlginates/tabid/4458/List/1/CategoryID/2/Level/1/Default.aspx?SortField=ProductName,ProductName

Hoping this will be helpful,

Rafik

dear rafik thanks for your helpful guidance.

Dear Mohammad,

As I know, sterilization using Gamma irradiation in the presence of water may significantly decrease the molecular weight of the alginate. Under gamma irradiation, water will form radicals that can attack the alginate compound and degrade it.

Have you tried filtration using 0.45 micrometer filter? I use this filter to filtrate polymer with molecular weight about 120 kDa and it works.