Green synthesis of graphene quantum dot- and its electrochemical, antioxidant and antimicrobial activities

The present work reports the synthesis of graphene quantum dots with a green approach. Graphene quantum dots (ssGQDs) were synthesized via Sarcopoterium spinosum (L.) Spach. fruit powder extract. The prepared ssGQDs were characterized by UV-Vis Spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and Malvern Zeta Sizer. The electrochemical activity of ssGQDs was investigated by cyclic voltammetry (CV) and differential puls voltammetry (DPV) methods. The synthesized ssGQDs were used to prepare electrosensor and tested for the electrochemical determination of dopamine. DPV studies showed a low detection limit of 0.107 μM over a wide linear concentration range of 10–800 μM. Antibacterial and antioxidant activities of synthesized ssGQDs were also investigated. The results showed that ssGQDs exhibited different antibacterial activity on Gram (+), Gram (-) bacterial strains and antifungal activity against fungal strains. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) hydrogen peroxide (H2O2) scavenging methods were used to examine the antioxidant activity of ssGQDs and were found to be effective.