In Vitro Cancer Cell Imaging, Free Radical Scavenging, and Fe3+ Sensing Activity of Green Synthesized Carbon Dots from Leaves of Piper longum.

The development of carbon dots via a green synthesis approach from natural products is one of the most researched areas nowadays. Herein, we present the synthesis of Piper longum leaves-derived aqueous carbon dots (PLACDs) via the simplest ecofriendly hydrothermal carbonization method. The PLACDs exhibited excitation-dependent emission behavior with maximum emission at 450 nm at an excitation wavelength of 365 nm. The High-Resolution Transmission Electron Microscopy results showed a quasi-spherical shape with an average size of 4.121 nm. The sharp diffractions of X-ray diffraction revealed its nanocrystalline property. The Energy Dispersive X-ray spectra reflected the presence of carbon, nitrogen, and oxygen. The Fourier-Transform Infrared Spectroscopy disclosed the existence of –OH, –C=C, –C=O, and –C–O–C groups. The PLACDs presented excellent biocompatibility against B16F10 (melanoma) and SiHa (cervical carcinoma) cells lines with concentration-dependent in vitro bioimaging results. It also exhibited antiradical activity with the IC50 value of 0.499 mg/mL and 0.051 mg/mL against DPPH and ABTS.+, respectively. It showed Fe3+ sensing with a lower limit of detection of 0.673 μM. Further, the PLACDs displayed excellent bacterial biocompatibility, pH-dependent fluorescence property, fluorescent ink property, photostability, physical, chemical, and thermal stability. [ABSTRACT FROM AUTHOR]