Self-healable flexible luminescent films based on silk fibroin and graphene quantum dots

Abstract

In this paper, thermally-stable, biocompatible and flexible luminescent films with self-healing capability were prepared by combining graphene quantum dots (GQDs) and silk fibroin (SF). Two methods were carried out to combine GQDs and SF: one is to feed silkworms with a GQDs diet and collect their cocoons; the other is to mix GQDs with SF solution directly. Then feeding GQDs/SF composite film and GQDs/SF mixing films of different mass ratios were prepared by natural air drying. The morphology, structure and performance of the SF films were characterized in detail. Results showed that the mixing composite films are flexible, luminescent and thermally stable. The more GQDs in the film, the stronger the luminescence is, in our case. The mixing films exhibit different light color under different excitations, the same with GQDs. However, fed GQDs in the silkworm seem to be playing a quenching effect on SF. It also showed that no new chemical bonds were formed between GQDs and SF, and the two were physically mixed, either by feeding or direct solution mixing. In addition, this fluorescent film also has the particular ability of self-healing by a drop of water. This new biocompatible film may have broad applications in fields of flexible display, biosensing, drug delivery and tissue engineering.

Photoluminescence properties of silk–carbon quantum dots composites

“…This suggests that the secondary structure of our silk contains both disordered structural elements, together with β-sheets. No changes are detected by increasing the CQDs content, indicating that no chemical bonds are formed between SF and CQDs during the sol-gel transition, and the particles are only physically mixed with the matrix, as already reported for similar composites with lower particles loading [12,25].…”

“…Since the environmental and biomedical application of hydrophilic polymers is affected by water stability, we also investigated the effect of methanol treatment on the PL and its degradability in terms of mass loss. Similar composites were recently reported by combining SF with graphene QDs [25], however, no studies of the crosslinking effect of the methanol treatment and the water stability of the nanocomposites were previously conducted.…”

Recent Progress in Self-Healable Hydrogel-Based Electroluminescent Devices: A Comprehensive Review

“…In general, the following statements can be made: Tough materials such cellulose nanocrystals could be incorporated in order to improve the mechanical stability of silk fibroin hydrogels [ 100 ]; To improve the stretchability and compressibility of hydrogels, polymers such as polyacrylamide, graphene oxide and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) could be mixed with silk fibroin [ 99 ]; Silk fibroin could be chemically modified using photo-cross-linking with glycidyl methacrylate to improve the tensile properties and environmental stability [ 98 ]; To improve the rheological and ion-conductive properties of silk fibroin, silk fibroin can be injected with xanthan gum with the help of cross-linkers [ 97 ]; Hydrogels for EL applications from silk fibroin are eco-friendly [ 102 ]; To obtain real-time self-healing hydrogels, silk fibroin has been combined with tannic acid [ 103 ]; To enhance electrical conductivity, silk fibroin can be combined with highly conductive materials, such as graphene [ 104 , 105 ], to obtain efficient EL devices; and Among the list of hydrogels for electroluminescence materials, hydrogels based on silk fibroin is one of the most researched one. …”

“…To enhance electrical conductivity, silk fibroin can be combined with highly conductive materials, such as graphene [ 104 , 105 ], to obtain efficient EL devices; and…”