Monday, April 27, 2009

Science v324, Issue 24

Some Solid-state 27Al MAS NMR can be found in the supporting information.

Science 24 April 2009:Vol. 324. no. 5926, pp. 488 - 492DOI: 10.1126/science.1168162

Greatly Increased Toughness of Infiltrated Spider Silk

Seung-Mo Lee,1,* Eckhard Pippel,1 Ulrich
Gösele,1 Christian Dresbach,2 Yong Qin,1 C. Vinod Chandran,3 Thomas Bräuniger,3 Gerd Hause,4 Mato Knez1,*

In nature, tiny amounts of inorganic impurities, such as metals, are incorporated in the protein structures of some biomaterials and lead to unusual mechanical properties of those materials. A desire to produce these biomimicking new materials has stimulated materials scientists, and diverse approaches have been attempted. In contrast, research to improve the mechanical properties of biomaterials themselves by direct metal incorporation into inner protein structures has rarely been tried because of the difficulty of developing a method that can infiltrate metals into biomaterials, resulting in a metal-incorporated protein matrix. We demonstrated that metals can be intentionally infiltrated into inner protein structures of biomaterials through multiple pulsed vapor-phase infiltration performed with equipment conventionally used for atomic layer deposition (ALD). We infiltrated zinc (Zn), titanium (Ti), or aluminum (Al), combined with water from corresponding ALD precursors, into spider dragline silks and observed greatly improved toughness of the resulting silks. The presence of the infiltrated metals such as Al or Ti was verified by energy-dispersive x-ray (EDX) and nuclear magnetic resonance spectra measured inside the treated silks. This result of enhanced toughness of spider silk could potentially serve as a model for a more general approach to enhance the strength and toughness of other biomaterials.

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