The optical properties of regenerated silk fibroin films obtained from different sources

Perotto, Giovanni; Zhang, Yuji; Naskar, Deboki; Patel, Nereus; Kaplan, David L.; Kundu, Subhas C.; Omenetto, Fiorenzo G.

doi:10.1063/1.4998950

Cited by 50 publications

(54 citation statements)

References 29 publications

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“…Finally, changes in amino acid composition of proteins may result in small but significant differences of refractive indices . However, refractive indices showed no significant changes in response to increasing degumming time (Figure B), in line with recently published results and potentially due to the fact that the contribution of repetitive elements of SF heavy chain dominate refractive index. This finding contributes to the conclusion that degradation primarily affected non‐repetitive regions of SF.…”

Section: Discussionsupporting

confidence: 92%

Effects of Silk Degumming Process on Physicochemical, Tensile, and Optical Properties of Regenerated Silk Fibroin

Nultsch

Bast

Näf

et al. 2018

Macro Materials & Eng

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Sericin removal from silk (degumming) affects material characteristics of silk fibroin (SF). Sodium carbonate is most commonly used for degumming, but numerous alternative methods are available. Herein, a systematic comparison of degumming methods is provided. Sodium carbonate, sodium oleate, trypsin, and ionic liquid are used, and materials are characterized regarding mass loss, SF content, molecular integrity of SF, refractive index, and tensile properties. Complete degumming is achieved within 30 min of using sodium carbonate, but results in significant reduction of molecular weight, shift toward less acidic charge variants, and reduction of yield‐ and rupture force. Sodium oleate and trypsin are inefficient and negatively affect tensile properties, while ionic liquid shows good efficiency and marginal degradation of SF but also reduced yield‐ and rupture force. Refractive index is not affected by degumming. These results allow rational selection of the degumming method and tuning of SF properties for biomedical applications.

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Section: Discussionsupporting

confidence: 92%

Effects of Silk Degumming Process on Physicochemical, Tensile, and Optical Properties of Regenerated Silk Fibroin

Nultsch

Bast

Näf

et al. 2018

Macro Materials & Eng

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“…It also displayed form birefringence 49 ( Supplementary Fig. 23b), owing to the refractive index difference between silk fibroin (n = 1.54) 50 and air as a result of the mesoporous feature, along with the orientational arrangement of silk nanofibrils 20 induced by the shear-force during the printing process.…”

Section: Resultsmentioning

confidence: 99%

Polypeptide templating for designer hierarchical materials

Sun

Marelli

2020

Nat Commun

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Despite advances in directing the assembly of biomacromolecules into well-defined nanostructures, leveraging pathway complexity of molecular disorder to order transition while bridging materials fabrication from nano-to macroscale remains a challenge. Here, we present templated crystallization of structural proteins to nanofabricate hierarchically structured materials up to centimeter scale, using silk fibroin as an example. The process involves the use of ordered peptide supramolecular assemblies as templates to direct the folding and assembly of silk fibroin into nanofibrillar structures. Silk polymorphs can be engineered by varying the peptide seeds used. Modulation of the relative concentration between silk fibroin and peptide seeds, silk fibroin molecular weight and pH allows control over nanofibrils morphologies and mechanical properties. Finally, facile integration of the bottom-up templated crystallization with emerging top-down techniques enables the generation of macroscopic nanostructured materials with potential applications in information storage/encryption, surface functionalization, and printable three-dimensional constructs of customized architecture and controlled anisotropy.

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“…We obtained regenerated silk fibroin from cocoons made by the domestic silk moth, Bombyx mori (Supplementary Information Section 7) 31 . By chemically removing sericin, regenerated fibroin offers substantially reduced absorption in the visible and near-infrared part of the solar spectrum 32 , while providing absorption properties similar to those of natural silk fibers in the mid-infrared region. Researchers have demonstrated that fibers extruded through wet spinning from a solution of regenerated fibroin can have a greater tensile strength than do natural Bombyx mori fibers 33 .…”

Section: Resultsmentioning

confidence: 99%

Nanostructured fibers as a versatile photonic platform: radiative cooling and waveguiding through transverse Anderson localization

et al. 2018

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Broadband high reflectance in nature is often the result of randomly, three-dimensionally structured materials. This study explores unique optical properties associated with one-dimensional nanostructures discovered in silk cocoon fibers of the comet moth, Argema mittrei. The fibers are populated with a high density of air voids randomly distributed across the fiber cross-section but are invariant along the fiber. These filamentary air voids strongly scatter light in the solar spectrum. A single silk fiber measuring ~50 μm thick can reflect 66% of incoming solar radiation, and this, together with the fibers’ high emissivity of 0.88 in the mid-infrared range, allows the cocoon to act as an efficient radiative-cooling device. Drawing inspiration from these natural radiative-cooling fibers, biomimetic nanostructured fibers based on both regenerated silk fibroin and polyvinylidene difluoride are fabricated through wet spinning. Optical characterization shows that these fibers exhibit exceptional optical properties for radiative-cooling applications: nanostructured regenerated silk fibers provide a solar reflectivity of 0.73 and a thermal emissivity of 0.90, and nanostructured polyvinylidene difluoride fibers provide a solar reflectivity of 0.93 and a thermal emissivity of 0.91. The filamentary air voids lead to highly directional scattering, giving the fibers a highly reflective sheen, but more interestingly, they enable guided optical modes to propagate along the fibers through transverse Anderson localization. This discovery opens up the possibility of using wild silkmoth fibers as a biocompatible and bioresorbable material for optical signal and image transport.

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The optical properties of regenerated silk fibroin films obtained from different sources

Cited by 50 publications

References 29 publications

Effects of Silk Degumming Process on Physicochemical, Tensile, and Optical Properties of Regenerated Silk Fibroin

Effects of Silk Degumming Process on Physicochemical, Tensile, and Optical Properties of Regenerated Silk Fibroin

Polypeptide templating for designer hierarchical materials

Nanostructured fibers as a versatile photonic platform: radiative cooling and waveguiding through transverse Anderson localization

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