Nope... ni siquiera agrendole el <?php ?> funciona :(
<?php $params = array(
"item_id" => $item_id,
"cat_id" => $cat_id,
"sub_cat_id" => $sub_cat_id,
);
$link = '<a href="%s">%s</a>';
echo sprintf( $link, "aportar_info.php?" . http_build_query( $params ), "<b>Aporta Informacion</b>" ); ?>