Impact of water-soluble 2D CdSe/CdS nanoplatelets on seed germination and early growth in Vigna radiata

Abstract

Cadmium chalcogenides nanoplatelets are two-dimensional semiconductor nanocrystals exhibiting high spectral brightness and unique size-dependent properties. CdSe/CdS nanoplatelets (NPLs) display potential as promising candidates for the light emission diode (LED), sensors, photovoltaics, and bioimaging. However, the environmental fate of the nanoplatelets raises a potential threat to living systems. To address the concern, we have synthesized the CdSe/CdS NPLs using the colloidal atomic layer deposition (cALD) method followed by surface modification with 2-mercaptoethanol to introduce water solubility. The TEM and XRD analysis confirmed a zinc blend crystal structure at the nanometer scale. The nanoplatelets negatively affected various germination parameters, plant height, and weight in Vigna radiata. The nanoplatelets instigated the phytotoxicity in root and shoot tissues in early plant growth. It also severely devastated the stress tolerance capabilities in the plant system. The damages incurred by the nanoplatelets were also confirmed by estimating the levels of plant antioxidant enzymes. The catalase enzyme activity was upshot in response to excessive levels of reactive oxygen species level triggered by nanoplatelets and cadmium exposure. Surprisingly, the peroxidases enzyme activities were substantially reduced due to toxicity induced by the nanomaterials and cadmium. The nanoplatelets, despite the confinement of cadmium and selenium in the nanostructure, could negatively impact plant growth and development. Our results showed that unique shape, small size, and oxidative nature of the nanomaterial enabled manifold destructions in the Vigna radiata. Therefore, we urge a proper regulation for the large-scale synthesis and utilization of the CdSe/CdS NPL.