- preg_replace: documentation ( source)
<?php
$text = 'Título ú Nota ó !¡ ! ';
$text = preg_replace('/[^áéíóúña-zA-Z0-9\', ]/i','',$text);
echo $text;
$mystring = 'Título ú Nota ó !¡ ! áéíóúñ )()&*%#$DR GT^(%(%(*&_{|}{jjkg cde d"';
$find = array ( '#[^a-z0-99áéíóúñ\\s]#is', '#\\s#' );
$replace = array ( '', ' ' );
$mystring = preg_replace ( $find, $replace, $mystring );
echo $mystring;