How to validate if text box have only special character?

i want to validate the text box.this is text box contain item number availability check .if the user enters only special character like( !@#$%^&+)(**)_)":}{?> )throw the alert message.
What I have tried:

i use

Regex r = new Regex(@"[~`!@#$%^&*()+=|\\{}':;.,<>/?[\]""_-]");
if (r.IsMatch(tbxspirno.Text.ToString().Trim()))
{
Master.ShowMessage("Enter valid item number", MessageHelper.MessageType.Information);
}