Utilizing dynamic html-attributes for the content is possible, as demonstrated here:
JSBin: http://jsbin.com/sepino/edit?html,css,js,output
<!DOCTYPE html>
<html ng-app="test">
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.0/angular.min.js"></script>
<script language="JavaScript">
angular.module('test',[]).controller('testController',function(){
this.textbefore = 'left ';
this.textafter = ' right';
});
</script>
<style>
.bar:before {
content: attr(data-textbefore);
height: 20px;
}
.bar:after {
content: attr(data-textafter);
height: 20px;
}
</style>
<meta charset="utf-8">
<title>JS Bin</title>
</head>
<body ng-controller="testController as myCtrl">
<div class="bar" data-textbefore="{{myCtrl.textbefore}}" data-textafter="{{myCtrl.textafter}}">inside</div>
</body>
</html>