Save Array in Persistent

I write an app on version 1.3 and now upgrade to 2.0.5. I use persistent for store setting(condition) like status and search term:

            $this->persistent->parameters['search'] = $this->request->getQuery('search','string');
            $this->persistent->parameters['status'] = $this->request->getQuery('status','int');
            $parameters = $this->persistent->parameters;
            $parameters // return NULL

but $parameters give me NULL

how I can save Array in persistent???

$parameters = array();
$parameters['search'] = $this->request->getQuery('search','string');
$parameters['status'] = $this->request->getQuery('status','int');
$this->persistent->parameters = $parameters;