Capturing functional two-dimensional nanosheets from sandwich-structure vermiculite for cancer theranostics

Clay-based nanomaterials, especially 2:1 aluminosilicates such as vermiculite, biotite, and illite, have demonstrated great potential in various fields. However, their characteristic sandwiched structures and the lack of effective methods to exfoliate two-dimensional (2D) functional core layers (FCLs) greatly limit their future applications. Herein, we present a universal wet-chemical exfoliation method based on alkali etching that can intelligently "capture" the ultrathin and biocompatible FCLs (MgO and Fe2O3) sandwiched between two identical tetrahedral layers (SiO2 and Al2O3) from vermiculite. Without the sandwich structures that shielded their active sites, the obtained FCL nanosheets (NSs) exhibit a tunable and appropriate electron band structure (with the bandgap decreased from 2.0eV to 1.4eV), a conductive band that increased from -0.4eV to -0.6eV, and excellent light response characteristics. The great properties of 2D FCL NSs endow them with exciting potential in diverse applications including energy, photocatalysis, and biomedical engineering. This study specifically highlights their application in cancer theranostics as an example, potentially serving as a prelude to future extensive studies of 2D FCL NSs. Clay-based nanomaterials are of wide interest but problems extracting the 2D functional core layers have limited potential applications. Here, the authors report on the wet exfoliation of vermiculite by alkali etching to obtain the core layers and explore the application of the materials in cancer theranostics.