Betaine-Modified\nGreen Carbon Dot for Cr(VI) Sensing,\nin Vivo Cr(VI) Imaging, and Growth Promotion in the Rice Plant

Hexavalent chromium is a toxic environmental\npollutant\nthat damages\nplants due to disruption of nutrient uptake, photosynthesis metabolism,\nand oxidative stress, which suppresses the growth and development\nof the plant. In this work, we have developed a betaine-modified carbon\ndot (BT@CD) sensor for monitoring Cr(VI) in water and plants. Fluorescent\ncarbon dots have been synthesized using jamun juice (Syzygium cumini) as the carbon source subjected to\nsurface modification with betaine (BT@JCD). This BT@JCD exhibits strong\nblue fluorescence, which significantly decreases in the presence of\nCr(VI) due to the inner filter effect in a range of 5–450 nM\nwith a detection limit of 0.033 μM. Due to its easy translocation\nin the vascular bundles, these fluorescence nanosensors can be applied\nto detect Cr(VI) in rice plants Oryza sativa) through fluorescence confocal imaging. The treatment of rice plants\nwith BT@JCDs in the concentration range of 0.2 to 1g/mL not only triggered\nphotophysical parameters such as carbohydrates, chlorophyll, and carotenoids\nbut also enhanced the antioxidant enzyme activity promoting plant\ngrowth.