Helix-Rich Silk Fibroin Films Incorporating Carbon Nanotubes and Microwave irradiation

Helix-Rich Silk Fibroin Films Incorporating Carbon Nanotubes and Microwave irradiation


In this paper we work with a very
interesting material, silk based materials These are natural fibers that humans
have been using for thousands of years because of their unique properties
their unique luster and lightweight and pleasant feel. It’s been used for
textiles for a long time but there’s a lot more to silk fibers than their use for textiles. More recently we started to recognize the unique bio-compatibility and bio-degradable properties of these materials and that
opened the door for many biomedical applications but the issue is that if we
want to use the silk materials for biomedical applications we don’t want it
to be in the form of fibers but rather in the forms of films that exhibit
interesting optical, mechanical and electrical properties so in this paper
we work on developing regenerated silk fibroin films which are
optically transparent mechanically flexible based on processing of these
natural fibers along with carbon nanotubes where we leverage the
interactions between the carbon nanotubes and the silk fibroins combined
with microwave heating and solvent annealing in order to tune their
properties Silk fibroin is mainly composed of kind of two kinds of amino acid: glycine, alanine up to 75% and the high content of these two amino acids results in a highly conserved protein sequence such as glycine, alanine, glycine, alanine like this and this conserved protein sequence prefers to form a beta sheet structure by hydrogen bonding between the protein molecules and this beta sheet structure leads to the exceptional mechanical properties of natural silke fibers.
However during the regeneration process the beta sheet structure turns into the amorphous stage
so it is very important to control the secondary structure of the regenerated silk fibroin such as alpha helix or beta sheet structures inorder to control the properties of regenerated silk fibroin.
After the silk regeneration process the resulting films are amorphous and highly
transparent in water this is why we need post-processing methods to induce the
formation of secondary structures such as alpha helix and beta sheets which
usually exhibit better mechanical and degradation properties. These methods include exposing the silk fibroin to solvents in vapor or liquid form which induce the
secondary structures in a process known as solvent annealing, alternatively we can use heating to induce the secondary structures in a process known as thermal annealing. We
can also use additives such as glycerol which has been shown to induce alpha rich structures in the silk matrix. We add surface functionalized Carbon Nanotubes to the silk fibroin matrix during the regeneration process and
after preparation of the composite film we use microwave heating irradiation for the local heating of
silk molecules nearby CNTs using the differences in electric conductivity between the CNT and the silk fibroin. And we confirm that the local heating of
silk molecules leads to local crystallization so we further investigated the effect of local crystallization on the mechanical properties of regenerated silk composite films. Our films exhibited enhanced water degradation and tunable mechanical properties. The film’s also exhibited enhanced
mechanical properties like 90% increase in mechanical strength and and an 80% increase in elongation owing to the synergetic CNT
reinforcement effects and the ductile properties of the alpha helix rich structure. The mechanical
and optical properties of our films are comparable to synthetic polymers such as PET with the added advantage of better sustainability and bio-compatibility as well. Our work enables a high degree of tunability of the structural properties of the regenerated silk fibroin films
and we’re excited about taking this further in the future and developing both
the science and technology aspects of creating these functional materials so
there is from a scientific perspective there is a lot more to do
in order to understand the interactions between the nanotubes, the
functionalisation of the nanotubes surfaces with the protein molecules and
from a technological perspective or an engineering perspective we want to
develop the process the manufacturing process for taking these cocoons of
natural silk fibers and transform them into a functional thin transparent and
flexible materials that are useful for many application such as flexible
electronics including sensors and memory devices you

Leave a Reply