Surface Modifications and Hydrophilic Transformations of Hydrophobic InSe 2D Materials for Biological Applications

Nanosheets are solid, layered two-dimensional nanostructures having properties unique and different from their bulk precursors, due to which they find potential applications in various fields. Our material of interest is InSe due to its many advantages, especially because it is an emerging material for electronic applications and is a direct bandgap semiconductor with high photoresponsivity. Usage of InSe and other 2D materials is expected to increase exponentially in the next decade. However, their unique morphology and ability to produce reactive oxygen species (ROS) can be detrimental to the environment. To address this environmental concern, our studies aim to understand the impact of surface chemistry modifications on the stability and interactions of these 2D materials with model membranes and bacterial organisms relevant to human health and the environment. Initially hydrophobic InSe nanosheets are synthesized by a facile kinetically controlled semi-bottom-up approach and are subsequently made hydrophilic and suitable for biological studies by surface modifications with different molecular ligands having varying toxicity via physisorption or chemisorption. A comparative study of the toxicity profiles of the differently modified hydrophilic InSe nanosheets is performed on <i>Shewanella oneidensis</i> MR-1, an environmentally relevant gram-negative bacterium. The goal is to understand the post-use fate of these materials on their disposal to the natural aqueous environment and design surface modification strategies to make them safer and sustainable for extensive environmental use. From a fundamental science perspective, this study should increase the molecular-level understanding of the interactions between hydrophobic 2D materials and their hydrophilic adsorbates.