In Situ Raman Spectroscopic Study of Al-Infiltrated Spider Dragline Silk under Tensile Deformation

Abstract

Natural materials consisting of protein structures impregnated with a tiny amount of metals often exhibit impressive mechanical behavior, which represents a new design paradigm for the development of biomimetic materials. Here, we produced Al-infiltrated silks by applying a modified Al2O3 atomic layer deposition process to the dragline silk of the Nephila pilipes spider, which showed unusual mechanical properties. The deformation behavior of the molecular structure of the Al-infiltrated silk was investigated by performing in situ Raman spectroscopy, where Raman shifts were measured concurrently with macroscopic mechanical deformations. For identifying the role of the infiltrated Al atoms, the study was performed in parallel with untreated silk, and the results were compared. Our experimental results revealed that superior mechanical properties of the Al-infiltrated silk are likely to be caused by the alterations of the sizes of the β-sheet crystals and their distribution.

Photoluminescence Mechanism and Photocatalytic Activity of Organic–Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration

“…14 Carbonyl (CO) containing polymers such as polyamides, 15,16 polyesters, 14,17 polyacrylates, 18,19 cellulose, 20 silk, 10,21 and biopolymers 22 have been infiltrated with common organometallic ALD precursors such as trimethylaluminum (TMA), 14 titanium tetrachloride, 10 and diethylzinc 20,23 for various applications. An important distinction between an SVI process and an ALD process is the sequence of precursor exposure.…”

Hybrid Spider Silk with Inorganic Nanomaterials

“…Additionally, peptides of hydrolyzed spider silk, which contain nucleophilic hydroxyls of cysteine, aspartic acid, and amines of histidine, can bind, for example, zinc oxide (ZnO) nanoparticles and bio-assist in the crystal growth of ZnO particles through the aggregation-driven mineralization [ 87 ]. Improvement in mechanical characteristics for potential applications in biomaterials were observed via in situ growth of TiO 2 , Al 2 O 3 in the spider silk via atomic layer deposition (ALD) infiltration [ 29 , 88 ]. More detailed discussion of the influence of oxides on the properties of spider silk is provided in the book of Cohen and Moussian [ 89 ].…”

Polymeric platform for the growth of chemically anchored ZnO nanostructures by ALD

“…27 The ability to control the reaction between the ALD precursors and polymers opens new opportunities in materials processing. 28,29 For instance, the exibility, transparency, lightness, and low costs typical of the plastic substrates can suitably encounter the photocatalytic, optical, and electronic functions of the metal oxides. Nevertheless, due to the severe chemical and physical differences between polymeric and inorganic components, the design of the ALD synthesis of a hybrid organic/inorganic material represents a signicant challenge.…”

“…On polymers such as PVA or cellulose where there is a large density of reactive groups, the ALD reaction can be limited to the top surface of the polymer. 19,29 In the case of the unreactive polymers towards the ALD reagents, no growth of the inorganic layer is observed for short times of depositions (few ALD cycles). The formation of the inorganic phase occurs, instead, for higher times of deposition with the precursors that can diffuse into the polymer and react within the lm, resulting in an inorganic phase embedded in the organic bulk.…”