Serialize DependencyObject : it's easy !

public class MyDependencyObject : DependencyObject
{
public static readonly DependencyProperty MyDependencyPropertyProperty =
  DependencyProperty.Register("MyDependencyProperty", typeof(String), typeof(MyDependencyObject));
 
  public String MyDependencyProperty
  {
    get { return (String)GetValue(MyDependencyObject.MyDependencyPropertyProperty); }
    set { SetValue(MyDependencyObject.MyDependencyPropertyProperty, value); }
  }
 
}
 
...
 
MyDependencyObject obj = new MyDependencyObject();
obj.MyDependencyProperty = "One love";
String serializedString = XamlWriter.Save(obj);
Console.WriteLine(serializedString);