Variable not recognised

558fe5180e0e8fc922d31c23ef84d240

From the below, how can I make the variable $new_status recognisable within those brackets?

$sendData = '{ "messages" : [ { "content" : "Your order is $new_status.", } ] }';

Problem: The above sends out text message successfully on status update, but the variable $new_status does not get updated.

I think within the those brackets php is not recognising the $new_status as a variable. I notice that if i insert one apostrophe (') just before $new_statusn like this '$new_status the variable turns green meaning it is recognised, however i get error in php that says Unexpeted T Variable