I am submitting form contents to my database with an array in Code Igniter. Here is the relevant code...

```
$sql= array (   
    'currency'=>$this->input->post('currency'),
    'total'=>$this->input->post('total'),
    'expenses'=>$this->input->post('expenses'),
        );
$ins = $this->db->insert('donations',$sql);

```

How do I escape £ signs in the currency field as it's written to the DB? I know I need to use a `str_replace()` with `&pound;` but can't get my head around the PHP.