Sustainable synthesis of multi-functional carbon dots as optical nanoprobe for selective sensing of heavy metal ions

Background

Carbon dots (CDs) are zero-dimensional fluorescent materials that attract attention due to their unique optical properties and size. This study utilizes Coccinia grandis (ivy gourd) for synthesizing CDs, focusing on detecting Fe³⁺ ions due to environmental and health concerns linked to iron levels. Iron imbalances can cause health issues like anemia and Alzheimer's disease, emphasizing the need for monitoring iron levels in water.

Methods

Coccinia grandis was utilized to synthesize CDs via one-step hydrothermal carbonization. Coccinia grandis fruits were carbonized through a hydrothermal process, resulting in the production of CG-CDs that were subsequently isolated and dehydrated to obtain a powdered form suitable for further analysis and application.

Significant findings

Characterization revealed CG-CDs with small (∼4 nm) and uniformly distributed particles, moderately graphitized. CG-CDs exhibited strong fluorescence without passivation agents, achieving a quantum yield of 17.5 % at 350 nm excitation. The CG-CDs were effective in sensing Fe³⁺ ions (limit of detection = 0.53 μM) in water, validated by a Stern-Volmer plot (R² = 0.997). This work demonstrates the potential of eco-friendly biomass like Coccinia grandis for producing efficient fluorescent sensors, aiding in Fe³⁺ ions detection for environmental and health applications.