Well the best solvent would be HFIP. For all the other parameter a quick search on google will give you an exhaustive list of process parameter. 

Hi Ankur.

thank you for your answer but when we use HFIP as a solvent for collagen and we want to reach electrospun collagen mat, the collagen degrade to gelatin. 

yes that is one of the most annoying thing about using collagen. HFIP does destroy its secondary and tertiary structure. I dont remember alternate solvent but i would suggest you to browse through the paper of gary wenck from case western. 

thank you

we use acidic solvent to solve collagen. did you think it is a good way? 

Solve collagen with acidic solvent  in freezer.

when we solve collagen in acidic solvent we always see a milky color of solution, is it good or bad?

 milky color is because of agitation or the high content of fat

Thank's God

Thank's Junjie