Is it possible Set ActionBar Title to Bold in Android?

I have got a NavigationRenderer like so:

[assembly: ExportRenderer(typeof(NavigationPage), typeof(MyApp.Droid.CustomRenderers.CustomNavigationPageRenderer))]  
namespace FieldStrikeMove.Droid.CustomRenderers
{
    public class CustomNavigationPageRenderer : NavigationRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<NavigationPage> e)
        {
            base.OnElementChanged(e);

            var actionBar = ((Activity)Context).ActionBar;
            //actionBar.TitleFormatted = ....
        }

    }
}

But how do I set the Title font to Bold. I can't work out how to use the TitleFormatted property?