Hello!
I am facing some problems regarding my current research project, which involves the bioprinting of Alginate and Gelatin for a cartilage scaffold. Basically, after optimising the printing process I would like to sterilise my powder to perform some initial tests on the hydrogel itself, but I have no clue on how to do it. I read online that the best way to sterilise this powder is by lyophilisation, dissolving the powder into water, filter the solution, freezing the solution, and lyophilise it. The problem is, how do I keep the sterilisation during the freeze-drying process? Is there a way to allow the water to flow out, while keeping the bacterias to contaminate my powder? I literally have no clue ahah.
Thank you very much for you help!
Giovanni
Make alginate solution and try with low sterilization temperature (e.g. 110 Celsius) for 10min. Always use clean dishes and water (better sterilized water). If You have automated autoclave, there is a program for specific (therm-sensitive) compounds (e.g. milk). You can try with UV sterilization of alginate powder. https://www.researchgate.net/post/What_is_the_best_method_to_sterilize_sodium_alginate_powder_or_solution_2_w_v
Autoclave the alginate solution at 121 °C for 20 minutes (sterilization). Estimated bench time: 15 minutes Estimated total time: 15 hours Purpose: This solution is used for creating the beads after the alginate droplets with bacteria are made. Dissolve 1.1098 g CaCl2 in 100 ml MiliQ. http://2015.igem.org/wiki/images/4/4c/TU_Eindhoven_Protocols_Alginate_beads.pdf
Check https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7114164/
We usually perform sterilizing filtration (0.22 microms) of alginate solution before using it. Isn't it possible for you?
Giovanni Gonnella, You probably should think about some radiation. As I think, one can combine freeze-drying with e.g. microwave heating. However, the freeze dryer would have to be redesigned.
First, thank you all for your replies! Chinaza Godswill Awuchi what you suggest seems like autoclaving, which is not good for the powder since it has already been proven to make the solution way more liquid by reducing the molecular weight of the powder. Same for gamma irradiation Mirosław Grzesik
Edorta Santos Vizcaíno I was thinking about this actually. At the moment I filtered 1% alginate in DI water and frozen it in a falcon tube. Now, the solution itself is filtered and sterile, but how do I ensure that during the lyophilisation process the sterility will be maintained? What do you usually use as a solution container? I read online that stopper caps can be used to close the vial with the frozen solution, but do these caps prevent bacteria/fungi contamination?
Again, thank you very much for all your replies!
Giovanni Gonnella, When writing about radiation, I did not mean gamme radiation, but microwave radiation. But this requires a specially designed lyophilizer, such as a microwave reactor, and control of the microwave intensity to heat the hydrocolloid rather than overheat. Will the freeze dryer ensure sufficient sterility, I do not know
how does protonation occur in sodium alginate, and how amorphicity facilitates protonation..........if possible could u explain this.........
You can use uv sterilised but not too long otherwise it will affect the chemical composition of the alginate.
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