Development of bio-hybrid piezoresistive nanocomposites using silk-elastin protein copolymers

Abstract

Recombinant silk-elastin-like protein (SELP)/carbon nanotubes (CNTs) nanocomposite films with different amounts of CNTs (1, 3 and 6 wt%) were prepared by solvent casting. The produced films were stabilized by exposure to methanol that induces an increase of the β-structure content. The CNTs were homogeneously distributed into the SELP matrix and did not induce significant alterations into its chemical structure. The incorporation of CNTs also increased the thermal stability of the films. Further, the incorporation of 1 wt% of CNTs greatly improved the mechanical properties of the SELP matrix leading to a 6-fold increase in strain-to-failure and to increase the ultimate tensile strength with minor differences in modulus of elasticity. The nanocomposites exhibited a good linearity between deformation and electrical resistance variation with electrical conductivity increasing with the nanofiller content up to 0.8 S m −1. Finally, the produced nanocomposites were non-cytotoxic indicating their suitability for biomedical applications.

Challenges in engineering conductive protein fibres: Disentangling the knowledge

“…In this case, the percolation threshold corresponds to the lowest allowable concentration of fibres in the network, below which the hydrogel conductivity drops significantly. [115] Percolation representation is independent of the predominant conduction mechanism, and rather indicates film conduction as a function of fibre length and density of filament junctions. [115] For conductivity measurements on films of purified pili from G. sulfurreducens, deviations from the percolation model can be attributed to fibre junction resistance.…”

“…[115] Percolation representation is independent of the predominant conduction mechanism, and rather indicates film conduction as a function of fibre length and density of filament junctions. [115] For conductivity measurements on films of purified pili from G. sulfurreducens, deviations from the percolation model can be attributed to fibre junction resistance. [31] Higher occurrence of capacitance effect is to be expected for a random network of filaments.…”

Environmentally Friendly and Biodegradable Ultrasensitive Piezoresistive Sensors for Wearable Electronics Applications

“…However, because PLA is brittle and has a high elastic modulus (around 50 MPa), 15 it is not suitable for highly deformable strain sensors. Biodegradable proteins like recombinant silk-elastinlike protein 16 is also brittle and has a high elastic modulus that limits its applications where high deformations are required, for example, to conform to the bending of the human finger, knee or human skin.…”

Recent Progress in Natural Biopolymers Conductive Hydrogels for Flexible Wearable Sensors and Energy Devices: Materials, Structures, and Performance

“…Although the silk fibroin based wearable sensors show excellent mechanical properties, they are still below the requirements of wearable sensors in practical applications, thus, it is necessary that diverse reinforcing strategies are proffered . For example, carbon materials such as graphene, carbon fiber, carbon aerogels, amorphous carbon, carbon black, carbon nanotubes (CNTs), and their hybrids have been extensively reported silk fibroin based sensor. − Among them, the recently studies have pointed that the wearable sensor composed of silk fibroin and graphene-based nanomaterials (GBNs) supply a facile approach to achieve conspicuous improvements both in the conductive properties and the mechanical properties for biomedical applications. − For example, tough silk fibroin/graphene oxide nanocomposite hydrogels were prepared via virtue of photocatalysis to trigger the covalent cross-linking of amorphous structures and tyrosine residues in silk fibroin and achieve chemically cross-linked silk fibroin/graphene oxide composites . Compared to the noncovalent interactions between graphene oxide and silk fibroin, the covalent bonding of tyrosine residues and amorphous structures in silk fibroin could further reinforce the mechanical properties of the hydrogel .…”