You would need to use Milton tablets or a steriliser bag or unit as they do not have the removable bottom part.
We have one of these for water and I chuck it in the microwave and never had an issue. I put about an ounce of cold water in the bottle and stack it like the photo but not screwed and lid loose. Personally I don’t like Milton sterilisers. Pop a cup in then drink a tea from it 🤮
These can but not just as the bottle. You’d have to buy sterilising bags or a sterilising pot for the microwave. Only the ones with the bottom can be self sterilising units as it were.