two font sizes in chart title

I currently have this string in my macro script.

With Worksheets("Graphs").ChartObjects(1).Chart
        .HasTitle = True
        .ChartTitle.Text = "Sample Text" & Chr(10) & "Text Sample2"
    End With

But i would like the first part in size 18 font and the second part in size 14 font.
Is this possible?

thanks in advance