Biological cell–substrate interactions with few-layered nanomaterials

Biology, fundamental to understanding life, remains a vitally important area of research. There is still much left for humankind to understand even after decades of research. This is clear now more than ever; as I write this, research has been disrupted for about 12 months due to various COVID-19 restrictions. Biology, therefore, is ripe for the fresh, new advances that result from interdisciplinary collaboration. Recent years have seen the exciting development of new few-layered materials, providing new possibilities in biology, as well as other areas. To this end, the work presented herein considers the interactions between different cell lines and various synthesised nanomaterial substrates. To distinguish effects due to the inherent biology of the cell and effects due to the nanomaterial substrate, well-defined substrates are crucial to interdisciplinary research. Thin films created by the Langmuir–Schaefer (L–S) deposition technique are a good candidate. This technique provides an easily controllable method of producing single-layer substrates. Here, a method resulting in improved understanding of the physical and chemical influences on L–S film formation is described. Surface pressure-surface coverage data can be normalised to nanosheet size to account for edge effects. This new approach allows the L–S film density to be determined from standard dispersion properties alone. In addition, this work produced the first demonstration of the production of single layer hexagonal boron nitride films using this method. To test nanomaterial–cellular interactions, various cell lines were seeded onto MoS2 L–S substrates. To the best of our knowledge, this study resulted in the first demonstration of the internalisation of MoS2 through mechanotransduction. The material showed localisation to the endoplasmic reticulum, which combined with the innate fluorescence or Raman signal of the MoS2 nanosheet, could lead to a new theranostic tool. This study was expanded to consider cell interactions with other transition metal dichalcogenide materials, WS2 and MoSe2, to investigate the difference between structure and chemistry seen by the cell. This work provides a step change to studying nanomaterial–cellular interactions, opening the door to new therapies and diagnostics.