Dear Dr. Hussain,

Thank you very much for the suggestion. So, you are suggesting to sterilize the lyophilized GelMA power and then to prepare the GelMA solution. Is it possible to sterilize the final solution of GelMA. Because, my concern is I may introduce any contamination during the mixing process.

Dear Muhammad,

GelMA solutions can be sterile filtered with a 0.2 um pore size filter, however, the filter membrane needs to be made of Polyethersulfone (PES). As you already pointed out, conventional filters typically clog. Nevertheless, it needs to be considered that sterile filtration may have an impact on your final polymer concentration, particularly for high molecular weight biopolymers. 

For better control of final GelMA concentration, I recommend sterile filtration before lyophilization. For more info, please refer to our recently published protocol (link attached).

Regards,

Christoph

Dear Christopher,

Thank you very much for the useful information. However, I can not see the attached link. Would you please re-post the link.

Best regards,

Noman

Sorry, please find the link below.

http://www.nature.com/nprot/journal/v11/n4/full/nprot.2016.037.html

Dear Christopher,

Thanks for the published protocol! it is very helpful, but how you keep the gelatin sterile after you weight it?

Dear Man, 

First, I weigh an empty (sterile) falcon tube on an analytical balance and note its weight (I do this 3 times and calculate the average weight obtained), then I transfer it into a biological safety cabinet and add sterile GelMA to it using sterile forceps and scalpel, then weigh it again 3x. I subtract the average weight of the empty tube from the average weight of the same tube with GelMA in it to obtain the dry weight of the macromere. 

Hope that helps.

Regards,

Christoph

Dear Christoph,

Thanks, it is very helpful !!!

Mandy.