preg_replace how

[eluser]basty_dread[/eluser]
is there a way to do this?
on preg_replace

$find = "web design services";
$string = "This is linked to Web design services . Find out more.";

the output should be:

This is linked to Web$design$services . Find out more.

and also preg replace to revert it back to

This is linked to Web design services

Please help on my problem

[eluser]basty_dread[/eluser]
this is my code for preg replace but i dont know how to put the $ symbol between the spaces of match string

Code:

$finalstring = preg_replace('/('.$find.')\b/iU', '<a href="asdf.com">\1</a>', $string,-1,$i);