I too accept with Amin Shavandi answer, In addition to it check the molecular weight of the precursor. If it is very less, even when you increase the concentration gradient you will be resulted with beads.
I think it can be due to low viscosity of solution...
And we ran this experiment with 2 ratio of CS/Gelatin (gelatin ratio is higher than CS)...
Dr. Arun, I would like to know which molecular weight of CS or Gelatin is more suitable for electrospining this blend. And which of them is more effective.
And how the molecular weight can influence on bead formation?(by influencing on viscosity?!)