Can someone suggest to me a way to sterilize my nanomaterial formulation? I have already tried the following strategies listed below:

1. Autoclaved the formulation twice.

2. Exposure to UV sterilization for more than 24h

None of the strategies were able to remove contamination. Media is not contaminated as it has been checked for contamination separately.

Can't go for syringe filtration as it is reducing the concentration of the formulation drastically.

So, is there any other method that can be adapted?