I had performed nanoparticles cytotoxicity on these cell lines. I want to know if these cells are dead then how do they look like. Answers will be appreciable.
Take an image every 15 seconds for 10 - 20 minutes. Then play them back in a sequential player. If they are alive parts of the cells will move significantly.
That is certainly not how HT1080 cells look. Your cells appear very unhealthy. The cell line is very aggressive and I suggest you passage them at regular intervals keeping in view that they are not growing to be over confluent.
This is how they traditionally appear under healthy conditions: http://www.atcc.org/~/media/Attachments/9/C/8/B/25818.ashx
What you have shown is cells are adherent to a support. But mine images are cells independent to enchoragement forming sarcospheres. I might be wrong i am not sure.