Dear all,
I am experiencing stability issues in my alginate microparticles which are produced in a microfluidic device through internal gelation.
My dispersed phase consists of Ca-EDTA (0.1-0.2 M) in 1-2wt.% alginate, while the continuous phase is mineral oil (once with and once without 1 vol.% acetic acid) containing 3 wt.% Span 80. Previously, I successfully produced alginate microparticles with a similar setup, using CaCO3 nanoparticles instead of Ca-EDTA. However, replacing Ca-EDTA with CaCO3 again has not led to any noticeable improvement.
Currently, my microparticles have uneven surfaces, and I observe debris in the continuous phase, which I suspect is due to incomplete gelation (see attached file). The literature presents a wide range of concentrations for alginate, Ca sources and acid, making it difficult to pinpoint why this instability is occurring now when it was not an issue before.
Has anyone encountered a similar problem and how did you solve it?
Thank you for your help
Instability in internally gelated alginate microparticles may stem from incomplete gelation due to ineffective calcium ion release or insufficient alginate cross-linking. Optimizing alginate concentration, calcium source, and acid levels can help stabilize the microparticles and improve their structural integrity.
Did you monitor de pH of your solutions ? maybe this can help : https://www.elveflow.com/microfluidic-applications/how-to-monodisperse-alginate-droplets-beads-production-microfluidics/
Thank you Abdelhak & Louise for your proposals. I was able to resolve the instability issue by reducing the acetic acid concentration down to 0.15 vol.%.
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