 
  
  $str = '$temp["items"][0]["title"][0]'$temp = json_decode($json, true);$str = '$temp["items"][0]["title"][0]';
$temp = json_decode($json, true);
$prepared_string = explode('[', $str, 2)[1];
$result = $temp;
foreach (explode('][', $prepared_str) as $part) {
    $result = $result[trim($part, '"]');
}
var_dump($result);