Enhanced Exfoliation of Biocompatible MoS2 Nanosheets by Wool Keratin

The unique properties of thin-layer transition metal dichalcogenides (TMDs) materials have been extensively investigated for both fundamental studies and practical applications in recent years. To develop the TMDs for medical engineering and bioelectronics in practical applications, the exfoliation and stabilization of TMDs using naturally biocompatible protein agents are in high demand. However, such strategies are far from being thoroughly studied. In this article, we present that wool keratin can assist exfoliation of MoS2 in aqueous solutions under sonication. And the wool keratin exfoliation of 2D material is systematically verified by molecular dynamics calculations and a series of experimental data observations. Moreover, compared with the traditionally used naturally biocompatible BSA under the same experimental conditions, wool keratin has been deemed to have an obvious better performance in exfoliating bulk MoS2. Relevant theoretical analysis indicates that high sulfur-containing functional groups on wool keratin molecules could provide sufficient possibility for the effective adsorption at the edges of MoS2 nanosheets. This discovery ensures that wool keratin biomolecules can provide superior colloidal stability for high concentration dispersion. The related investigations indicated that the biocompatibility of wool keratin (WK)-MoS2 films can also be demonstrated well on the basis of cell proliferation and viability assays. We also proved that wool keratin has a universal property for exfoliation of other types of two-dimensional materials. This discovery offers some new ways and opportunities for exfoliation of MoS2 and its biological applications.