using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string text = "Testing (ttro) and [TTRO] and {TtRo}";

Regex regex = new Regex(@"[\(\[\{][Tt][Tt][Rr][Oo][\)\]\}]");

​

MatchCollection matches = regex.Matches(text);

foreach (Match match in matches)

{

    Console.WriteLine(match.Value);

}

​

    }

}