Green synthesis of carbon dots from the defensive secretion of Luprops tristis for biomedical applications

We have developed a straightforward and eco-friendly one-step hydrothermal synthesis method (100 °C for 5 min) to produce Carbon Dots (CDs) derived from a common beetle species Luprops tristis (L. tristis), a novel source among various green sources of CDs. These CDs exhibit robust fluorescence, making them suitable for bioimaging, biosensors, and antibacterial treatments. They demonstrate high stability without the need for surface passivation additives, and their versatile surface groups enable compatibility with bioanalytical techniques and solubility in hydrophilic solvents. The UV-Vis spectrum shows an absorption peak at 225 nm, corresponding to π-π* transitions of the C = C bond. FTIR spectra highlight functional groups involved in the formation and reduction of these CDs, while Raman spectroscopy confirms the D and G band of CDs. TEM analysis also revealed that the prepared CDs were uniformly distributed with an average particle size of 3.9 nm. XRD analysis revealed a broad diffraction peak around 23°, confirming the amorphous graphitic nature of the biosynthesized CDs derived from L. tristis. These characteristics position CDs as promising biomedical tools for monitoring human health. Furthermore, the synthesized CDs have demonstrated effective antibacterial properties against both Gram-positive and Gram-negative bacteria, antioxidant properties, and anticancer properties towards DLA cells. Overall, the attributes of these environmentally friendly CDs suggest they can be readily scaled up for large-scale production without harmful chemicals, highlighting their potential in sustainable biomedical applications. Although CDs have been synthesized from various green sources documented in the literature, deriving CDs from insect secretions has not been recorded. This study presents a novel and innovative approach by synthesizing CDs from L. tristis secretions, revealing significant potential for biomedical applications.