how to search Unicode value Linq

Question

i have page search thread with keyword support unicode 

example:keyword hung will display result hùng and  hung

my code in linq:

from thread in db.thread .Where(o => (!String.IsNullOrEmpty(key)) ? thread.content.Contains(

key) : true)

i have try add method removeunicode

from thread in db.thread .Where(o => (!String.IsNullOrEmpty(key)) ? removeunicode(thread.content).Contains(

key) : true)

 but it's error linq to entities does not recognize the method

Please help me,thanks very much!