Yasmeen Akhtar We need far more information about the nature of the material, its concentration, and its mode of preparation in order to even begin to address your question. The concentration of phosphate in PBS is high and could be destabilizing the system - this is one of many possibilities.

And what about water? Are your particles stable in water?

Completely agree with you Alan F Rawle .

Furthermore, what type of stability is important to the application? Are we looking to prevent aggregation, retain shape, electroactivity, bioactivity, etc.

I have also found that people use the term PBS to describe very different buffers.