Recently, nanoparticles like Ag, CeO2, MnO2, ZnO,… with antioxidant activity have emerged as candidates for decreasing an oxidative stress as they do not only exhibit targeting ability but also because their lifespan in the kidneys is much longer than that of lower molecular weight organic compounds. However, their stability in vivo and the release of metal cations pose some safety concerns and could lead to high toxicity. Hence, the development of biocompatible nanoparticles exhibiting antioxidant properties remains a topical issue. Carbon quantum dots (CQDs) are zero-dimensional nanoparticles with sizes below 10 nm composed of arrangements of sp2/sp3/sp2-sp3 hybridized carbonaceous clusters exhibiting edge effects, defects and their electronic structures are influenced by the quantum confinement effect [1]. The carbon core of CQDs is substituted at the edge by carboxyl, carbonyl, hydroxyl and amino groups which allows these nanoparticles to be easily dispersed in aqueous media and functionalized. CQDs have recently gained high interest due to their low cost, high stability and photostability, biocompatibility and tunable photoluminescence (PL) from the UV to the near-infrared and have found many applications in optoelectronic devices [2]. Their favourable optical properties like high PL quantum yield (QY) and long PL lifetime have also led to their use in applications such as bio-imaging and sensing. This work presents the facile and single-step hydrothermal synthesis of CQDs using the Dichrostachys glomerata extract as raw material. CQDs with the highest photoluminescence (PL) were obtained after heating the extract in 4M NaOH at 200°C for 7 h. The obtained CQDs exhibit an average size of ca. 4.7 nm, a green-yellow PL emission independent on the excitation wavelength with contributions located at 478 and 562 nm, a monoexponential decay of their PL lifetime and a PL quantum yield of 18%. These results indicate that the surface functionalization of sp2 clusters in CQDs is uniform. The antioxidant properties of CQDs were also investigated. CQDs can effectively reduce free radicals like superoxide or oxidants like KMnO4. Moreover, CQDs show a high Cu2+ chelating activity, which is attributed to the abundant carboxylate functions on their surface and may therefore be of high interest in therapeutic applications related to Cu2+ ions overload. References [1] X. Kou, S. Jiang, S.-J. Park, L.-Y. Meng, Dalton Trans. 2020, 49, 6915-6938. [2] T. Yuan, T. Meng, P. He, Y. Shi, Y. Li, X. Li, L. Fan, S. Yang, J. Mater. Chem. C 2019, 7, 6820-6835.