From phytotoxicity to growth stimulation: Contrasting effects of Ti3C2T MXene and MoAlB@MBene on higher plants

Novel 2D nanomaterials offer the potential in addressing environmental challenges such as pollution and waste management, water scarcity, and agricultural limitations. While their catalytic and oxidative properties aid pollutant degradation, carbon sequestration, water treatment, and crop improvement, thorough phytotoxicity evaluation is necessary before application. In our study, we developed Ti 3 C 2 T x MXene and MoAlB@MBene, each showcasing unique structures and chemistries. DLS, zeta potential, and EDS analyses elucidated their size distribution, stability, and elemental composition. XRD confirmed efficient MAX into MXene transformation and MBene’s single-phase nature, while FT-IR suggested relatively pure surface chemistries. UV-Vis spectroscopy revealed plasmonic peaks for MXene, and UV absorption edge for MBene. To assess biological impact, we conducted a phytotoxicity evaluation based on germination efficiency, root and shoot elongation, biomass accumulation, and chlorophyll quantitative and qualitative studies. Ecotoxicity assessments on higher plants revealed MXene's concentration-dependent phytotoxicity, in contrast to growth-promoting MBene. Microscopic observations detailed MXene-induced root meristem disruptions, while MBene stimulated lateral root growth. Mass analyses demonstrated MXene-induced dry mass increases, even by 22% at 1000 mg dm -3 , relative to the control, contrasting with MBene’s vitality preservation and the carbon cycle. Chlorophyll and its fluorescence studies revealed MXene-induced stress, whereas MBene exhibited positive or neutral. Crucially, XRF analysis suggested limited nanomaterial uptake by plants. Altogether, our study introduces a novel approach to evaluating 2D nanomaterials' phytotoxicity, emphasizing the need to understand potential risks before application. While these materials offer environmental benefits, our findings show that careful evaluation is key to ensuring safe and sustainable use in real-world scenario. Our study on 2D nanomaterials reveals MXene’s phytotoxicity and MBene’s biocompatibility, highlighting their distinct impacts on plant growth and offering insights into future agricultural and ecological applications. • Assessed phytotoxicity of Ti3C2Tx MXene and MoAlB@MBene on higher plant species • Ti3C2Tx MXene inhibited root growth and altered chlorophyll fluorescence in plants • MoAlB@MBene promoted lateral root formation and biomass accumulation • Microscopy showed Ti3C2Tx MXene disrupted root meristem structure • MXene triggered stress responses, while MBene maintained chlorophyll stability