“…Out of the two, PVD typically requires high processing temperature and is not suitable for coating complex structures [ 20 ]. There have been many advances in PVD techniques, such as ion-beam assisted deposition (IBAD) [ 21 , 22 ] and RF sputtering [ 23 ], to allow lower deposition temperatures, but these usually involve the use of high energy sources which might damage the collagen structure [ 24 , 25 ]. In fact, IBAD of MgO has also been reported at room temperature on glass(SiO 2 ) substrates [ 22 ], however due to the well-documented damage ion beams can have on organic matter, it was not considered suitable.…”