Noble Metal Composite Porous Silk Fibroin Aerogel Fibers.

Alexander Mitropoulos,J Wickiser,R Sims,Madeline Ryu,F Burpo,Chi Nguyen,Kamil Woronowicz,Enoch Nagelli,Jenny Wang

doi:10.3390/ma12060894

Abstract

Nobel metal composite aerogel fibers made from flexible and porous biopolymers offer a wide range of applications, such as in catalysis and sensing, by functionalizing the nanostructure. However, producing these composite aerogels in a defined shape is challenging for many protein-based biopolymers, especially ones that are not fibrous proteins. Here, we present the synthesis of silk fibroin composite aerogel fibers up to 2 cm in length and a diameter of ~300 μm decorated with noble metal nanoparticles. Lyophilized silk fibroin dissolved in hexafluoro-2-propanol (HFIP) was cast in silicon tubes and physically crosslinked with ethanol to produce porous silk gels. Composite silk aerogel fibers with noble metals were created by equilibrating the gels in noble metal salt solutions reduced with sodium borohydride, followed by supercritical drying. These porous aerogel fibers provide a platform for incorporating noble metals into silk fibroin materials, while also providing a new method to produce porous silk fibers. Noble metal silk aerogel fibers can be used for biological sensing and energy storage applications.

Highlights

Biopolymers provide unique applications in advanced technology where degradation combined with natural materials are required
We have shown that HFIP–silk fibroin aerogel fibers can be utilized as a platform to anchor noble metal nanoparticles onto the surface of silk nanofibrils
Weare have shownofthat aerogel fibers canare bebased utilized as a on platform to nobility, not the concentration. This changes the mass percentage, porosity, surface area, and pore anchor noble metal nanoparticles onto the surface of silk nanofibrils

Summary

Introduction

Biopolymers provide unique applications in advanced technology where degradation combined with natural materials are required. Biopolymers take several forms, such as films, fibers, gels, and sponges, which are optimized for their required applications [1,2]. Producing the equivalent forms with the desired qualities in regenerated biopolymers has been challenging, especially making fibers with controlled diameters and porosity [2]. Working with regenerated biopolymer solutions can enhance properties such as the tensile strength and porosity [3]. Regenerated biopolymer solutions can be used as a structural network that can be combined with other materials to synthesize composites not found in nature [4,5]. Starting with biopolymers dissolved in polar solvents, such as water or alcohols, can be useful in providing varied biopolymer conformational folding to enhance the desired properties

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