Metal infiltration into biomaterials by ALD and CVD: a comparative study.

Atomic layer deposition (ALD) is a subset of chemical vapor deposition (CVD) and both use very similar chemistry. Recently, it has been reported that ALD has the potential to realize a new design paradigm of bioinorganic materials through metal infiltration, which in nature has been employed as a hardening strategy for many tissues in diverse biological organisms. Herein, using a spider dragline silk and a collagen membrane as targets, we have performed a comparative study to elucidate the difference of the metal infiltration effect by ALD and CVD. From the comparison of mechanical properties, concentration of the infiltrated metal, and structural changes induced by the infiltrated metal, it has been proven that the metal can effectively infiltrate biomaterials by ALD and the infiltrated metal leads to highly improved mechanical properties accompanied by substantial changes in the protein structures, whereas CVD is less effective.