[development] Is it possible to serialize the output of a custom block and unserialize the value in a page.tpl.php ?

Hello, I am trying to serialize the output of a block, which is received in a page.tpl with the $content variable. It seems it does not work, but I don't know why, because I can output the serialized string (using $content) in a page.tpl.php file but if I try to unserialize it and afterwards try to print_r the result, it shows nothing. Does anybody have any clue? It seems quite weird to me...