Biomass-derived coriander carbon quantum dots for oxidative stress mitigation and nanoscale imaging in plants

Biomass-derived nanomaterials have attracted attention as sustainable, biocompatible platforms for cross-kingdom applications in biology and agriculture. Among them, carbon quantum dots represent a promising class of nanomaterials with low toxicity and the ability to serve as fluorescent probes, biosensors, and theranostic agents. Here, we report a facile one-pot solvothermal method for synthesizing coriander-based carbon quantum dots (CCDs) from the bioactive ethyl acetate fraction of coriander seeds ( Coriandrum sativum L.) without the addition of surface passivating agents. Structural characterization via Fourier-transform infrared spectroscopy (FTIR) confirmed their surface functionalities, and high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS) confirmed the formation of uniform nanoparticles (<5 nm). The resulting biomass-derived CCDs exhibited a quantum yield of ∼25 %, durable fluorescence, high aqueous stability, and negligible cytotoxicity. We first validated the CCDs using in vitro cellular models and demonstrated that they are efficiently internalized by senescent human chondrocytes, with selective accumulation in the endoplasmic reticulum (ER). Confocal imaging and functional assays demonstrated their ability to mitigate oxidative stress, decrease reactive oxygen species, and restore ER network structures disrupted by senescence. Treatment also upregulated collagen type I expression, indicating a rejuvenative effect on stressed cells. Furthermore, we evaluated their potential as nanoscale imaging probes using Japanese brown rice ( Oryza sativa L.) grains as a model. Fluorescence imaging verified the absorption and distribution of CCDs within rice tissues, underscoring their utility as in situ probes for monitoring plant physiology. Our proof-of-concept study validates coriander-derived CCDs as versatile nanomaterials with cross-kingdom functionality, offering potential in both cellular rejuvenation and agricultural nanobiotechnology.