Как определить содержит ли строка специальные символы ?

static void Main(string[] args)
{
    string str = "Th!s $tri^g c@n$ist $pecial ch@rs";
    Match match = Regex.Match(str, "[^a-z0-9]",
            RegexOptions.IgnoreCase);
    while (match.Success)
    {
        string key = match.Value;
        Console.Write(key);
        match = match.NextMatch();
    }
    Console.ReadLine();
}

Shared Sub Main(ByVal args() As String)
    Dim str As String = "Th!s $tri^g c@n$ist $pecial ch@rs"
    Dim match As Match = Regex.Match(str, "[^a-z0-9]", _
RegexOptions.IgnoreCase)
    Do While match.Success
        Dim key As String = match.Value
        Console.Write(key)
        match = match.NextMatch()
    Loop
    Console.ReadLine()
End Sub