Hello Victor,

Greetings from Colombia

You should try sterilize in a ultrasonic cleaner that kills the cells by membrane disruption. 

I hope i have been helpful.

Good luck

u can use alcohol then rinse the sample with PBS, hope this will help, good luck.

ETO sterilization is one of the good method. you can rinse in PBS before use

You may want to check the following paper:

Article Influence of sterilisation on a sodium carboxymethylcellulose gel