Toxicological Effectsof Metal‐Doped Carbon Quantum Dots

Multi‐domain biological and environmental research highlights the efficacy of carbon quantum dots (CQDs) as asafer alternative to toxic metal‐based quantum dots (QDs) and expensive conventional organic dyes, particularly in biomedical applications. CQDs are often functionalized by metal heteroatoms to improve their electron‐donating properties and modify charge density, thereby enhancingtheir physicochemical characteristics. However, metal doping may re‐introduce toxicity concerns as in traditional QDs and further increase environmental risks.Thus, detailed ecotoxicology studies are necessary to understand the environmental impact of these CQDs indifferent organisms. To address this, we synthesized metal‐doped CQDs (Mn, Fe, Cu and Ag) usingmicrowave‐assisted technique and conducted in‐vitro experimentson diverse biological models belonging to different trophic levels, including bacteria (E. coli andB. subtilis), plants(Vignaradiata) and mammalian cells (mouse myoblast cells‐ C2C12).Results revealedthat among all the CQDs explored, Ag‐CQDs exhibited highest toxicity causing ~85% bacterial and 100% mammalian cell death even at 10 μg mL‐1 and ~60%radicle growth inhibition after 5 days of exposure at 50 μgmL‐1, whereas Mn‐CQD showed the least toxicity. These findings contribute significantly to the critical need for determining optimal concentration ranges for metal‐doped CQDs and enhance our understanding of their environmental implications.