Nanobionic enhancement of plant growth via copper nanoclusters in Raphanus sativus

Abstract Copper-based nanobionics offer a promising route to enhance photosynthetic efficiency and crop productivity. In this study the application of two photoluminescent copper nanomaterials, cysteine-stabilized copper nanoclusters (Cu-Cys) and copper-doped carbon nanoassemblies (Cu-CNAs) were used in studies of Raphanus sativus (radish), evaluating their uptake, physiological impact, and metabolomic response. Direct application of the optimal Cu-CNA concentration (250 mg·L⁻ 1 ) with seed priming resulted in a 63% increase in radish dry mass and a 31% increase in foliar dry mass, accompanied by a statistically significant 23% rise in chlorophyll absorbance (p* < 0.005) and a 67% increase in vitamin C concentration. ICP-MS confirmed up to 225% copper enrichment in foliage compared to the control, while CT imaging revealed a 49 Hounsfield Unit reduction in tissue density, indicative of accelerated cell expansion and increased porosity. MRI T₂ relaxometry showed stable hydration profiles, suggesting no adverse impact on water distribution. Untargeted metabolomics revealed upregulation of nicotinic acid, glycerophosphocholine, and stress-related amino acids such as alanine and pyroglutamyl-isoleucine. These metabolic shifts indicate a mild stress-induced reprogramming that coincides with the enhanced growth and structural improvements observed during both greenhouse trials. These findings demonstrate that Cu-CNAs can synergistically improve nutrient delivery and the crop growth rate, offering a sustainable and scalable strategy for photosynthetic enhancement.