How to use binding {{}} instead of ng-bind?

I want to add a link with the binding in a grid-item like this:
`<a ng-href="book/{{item.id}}"/>` 
but the binding doesn't work. How can I do this? I get empty value. This works well:
`<span ng-bind="item.id">`
But I want an 'a' not  a span. How can I achieve this?
