Can i use arduino uno for Asic ?
ASIC = application-specific integrated circuit
this is usually an integrated circuit chip customized for a particular use, rather than intended for general-purpose use...
Your UNO is more general purpose... so does not meet the definition in my opinion.
If the question is Can you run custom code on your UNO? then the answer is yes.
Do you mean Can i use arduino uno AS an Asic ? The answer is that you can make what looks to the outside world an ASIC using an Arduino along with your own code.