SpiderMAEn: recombinant spider silk-based hybrid materials for advanced energy technology

Abstract

A growing energy demand requires new and preferably renewable energy sources. The infinite availability of solar radiation makes its conversion into storable and transportable energy forms attractive for research as well as for the industry. One promising example of a transportable fuel is hydrogen (H2), making research into eco-friendly hydrogen production meaningful. Here, a hybrid system was developed using newly designed recombinant spider silk protein variants as a template for mineralization with inorganic titanium dioxide and gold. These bioinspired organic/inorganic hybrid materials allow for hydrogen production upon light irradiation. To begin with, recombinant spider silk proteins bearing titanium dioxide and gold-binding moieties were created and processed into structured films. These films were modified with gold and titanium dioxide in order to produce a photocatalyst. Subsequent testing revealed hydrogen production as a result of light-induced hydrolysis of water. Therefore, the novel setup presented here provides access to a new principle of generating advanced hybrid materials for sustainable hydrogen production and depicts a promising platform for further studies on photocatalytic production of hydrogen, the most promising future fuel.

The Power of Silk Technology for Energy Applications

“…Upon particle immobilization, Au and TiO 2 nanoparticles were perfectly aligned along the stripes, and the interface in between was found to successfully be able to catalyze the photoinitiated splitting of water producing hydrogen under the exposure of light at the visible wavelength providing a basis for further development of recyclable hybrid materials for water splitting photocatalysis. [52] The result of Herold et al is of particular interest for several reasons. First, the specific binding of nanoparticles was accomplished through explicit genetic modification of the protein, that is, protein engineering.…”

“…This includes the changing of the residual electric charge of the protein, [47,48] the introduction of protein sequences that fluoresce, [49] show affinity for specific cells types, [50,51] and bind specific chemical species. [52,53] The introduction of artificial binding sites on the proteins permits the formation of composites and hybrids which change the property of silk well beyond mere aesthetics as had been done with dyes for millennia. [54,55] This is highly relevant as an interest in organic-inorganic hybrids is growing in recent years due to the potential of combining the various functionalities of inorganic materials with the useful properties of silk such as good processability, excellent mechanical properties, being light weight, and biocompatibility.…”

“…In addition, as demonstrated by Shi et al, combining these conductive fillers with other proteins only enhances their compatibility with silk. With recent advances in fabrication of conductive nanocomposite silk films, [70] the specificity of silk binding motifs [52] and myriad of different types of spider silks, insect silks, and crustacean silks to choose from, there is a large number of untapped potential of silk materials for future flexible electronics.…”

“…[18,80] Recombinantly produced silk proteins also offer potential functionality and tunability. These tailorable protein sequences could add specific binding motifs, [52] or add antibacterial properties [81] to name a couple of examples. Regardless of which direction electronic textiles develop in the future, silk will play a role in its development.…”

“…In a paper by Herold et al recombinant spider silk was successfully modified with respective binding motifs to selectively interact with Au and TiO 2 nanoparticles, designated ntag cys eADF4(κ16) and eADF4(C16)-TiO 2 -bp, respectively. [52] Using a facile technique of film casting and capillary force-based patterning, the proteins were processed into patterned films with a base of Au-binding ntag cys eADF4(κ16) and stripes of TiO 2 -binding eADF4(C16)-TiO 2 -bp (Figure 7). Upon particle immobilization, Au and TiO 2 nanoparticles were perfectly aligned along the stripes, and the interface in between was found to successfully be able to catalyze the photoinitiated splitting of water producing hydrogen under the exposure of light at the visible wavelength providing a basis for further development of recyclable hybrid materials for water splitting photocatalysis.…”