Dear Shuaiqi,

There are several methods that you can exploit, but you have to considere the different impact of each methods on the physiochemical properties of you alginate solution and therefore on its printability:

Method 1 - UV sterilization: I Guess you have a biological Hood with a bactericidal UV lamp. Therefore you can put your alginate powder under the UV lamp and sterilize for 1h. Then add the sterile medium (PBS, DMEM,..) that you usually use for encapsulating cells. This method does not impact at all on the properties of your bioink but has the lowest sterilization efficiency.

Method 2 - Sterile Filtering: Prepare your alginate solution and then pass It through a sterile 0.22 micron filter obtaining a sterile solution. Be aware that depending on the molecular weight of your alginate this process could be really difficult (the higher the MW the higher the pressure needed), moreover, the finale concentration of the sterile solution could be slightly lower impacting on your printing process.

Method 3 - Autoclave: Prepare your alginate solution and sterilize It by autoclave. Personally i never tried this option but i know It can be performed. I Guess It cannot be applied if you dissolve the alginate in Cell culture medium but only in PBS. Furthermore, also this approach has an high impact (maybe the highest among the different methods) on the printability of your bioink because of the reduction of MW of alginate during autoclaving.

I sincerely hope that these indications can help you somehow!!

UV exposure for alginate powders