Abstract
Antibacterial agent based on modification of Macaranga tanarius (M. tanarius) extract into CQDs@M. tanarius has been successfully synthesized and applied against Escherichia coli and Staphylococcus aureus. Macaranga tanarius plants were obtained from Buton Island, Southeast Sulawesi-Indonesia, and used as precursors for Carbon Quantum Dots (CQDs). In the synthesis, the dried leaves of M. tanarius were macerated, and then the filtrate was modified hydrothermally in a Teflon-lined stainless steel autoclave. The modification results produce nano-sized CQDs@M. tanarius particles. The PSA test confirmed this, which described the CQDs@M. tanarius particle size as 57.0 nm. The results of UV-Vis spectroscopy tests illustrate that the CQDs@M. tanarius molecules experience π → π* and n → π* electronic transitions at a wavelength of 367 nm. Meanwhile, in the FTIR spectroscopy test, stretching vibrations from the functional groups -OH, C-H, C=O, C-O, and the benzene ring were observed at wave numbers 3415.93 cm(-1), 2976.16 cm(-1), 1641.42 cm(-1), 1274.95 cm(-1), and 692.44 cm(-1), respectively. Based on the antibacterial activity test, it is known that CQDs@M. tanarius has high inhibitory activity against E. coli and S. aureus. The resulting inhibition diameters are 15.82 mm and 11.24 mm, respectively. This high inhibitory diameter further illustrates the potential of CQDs@M. tanarius for its further application as an antibacterial material in the future.