What a unique symbol to use to explode?

I connect to a string data I need using the delimiter ";"
$getJson = sprintf("%s;%s, $var, $var2);

Then get:
explode(';', $getJson);

And there is a problem that in $var2 can be any text and if found the symbol ";" , break wrong.
What you can come up with such a unique character (or character set) that just will not use in the text? Or how to solve this?