Yes, Paul made use of amanuenses. We see this in Galatians 6:11, where Paul says, "See with what large letters I am writing to you in my own hand!" You should be clear about what an amanuensis actually is. It is a person who acts as a secretary taking dictation. With that in mind, the letters remain Paul's, not the secretary's. Paul says he is using large letters. Some scholars think this indicates Paul had poor eyesight and that he was using an amanuensis to help write the bulk of the letter, leaving the closing for himself.