If you see the basic structure of collagen (from several references available online) you too can understand that citric acid is ideal for electrospinning of collagen. To explain this here, there will be paucity of space as it involves a lot of basic biochemistry.

Well, I found a very nice article, which is using acetic acid " Engineering of a Stable Collagen Nanofibrous Scaffold with Tunable Fiber Diameter, Alignment, and Mechanical Properties". I think that the idea to use citric acid is very good as it is a non toxic solvent.  Good luck 

Dear sir Jai Ghosh, if possible could you please put some references or titles that could strengthen my understandings of the logic for possibility of electrospinning of collagen. Looking forward to have some more feedback.thanks

Go to PubMed and you will find all the reference you want. I really appreciate Gloria's answer which is a glimpse of what you can read further.