Functionalized carbon quantum dots with tunable optical properties widely used in sensor applications. In this study, carbon quantum dots were synthesized from Zelkova serrata leaves (ZCQDs) in an aqueous medium via a single-step hydrothermal reaction with essential reactive functional groups. As-synthesized ZCQDs (average size, 3–7 nm) were characterized and confirmed to contain hydroxyl/amine and carboxylic acid functional groups. Photoluminescence spectral analysis revealed that the fluorescence intensity of ZCQDs drastically decreased after the addition of different concentrations of normetanephrine (NM) in deionized water and geriatric plasma samples. Our developed strategy could detect NM with a limit of detection of 7.96 and 86.2 nM in deionized water and geriatric plasma samples, respectively. Interestingly, Fourier transform infrared spectroscopy revealed a new peak at 1660 cm⁻¹, confirming the formation of the keto (C=O) group in NM. In addition, significant peak shifts were observed in the C 1s, and O 1s deconvoluted X-ray photoelectron spectra. Bandgap calculations also revealed significant interactions between NM and ZCQDs. Antibacterial activities of ZCQDs were investigated in Escherichia coli and Staphylococcus aureus, and potent activities were observed in Staphylococcus aureus at a half-maximal inhibitory concentration of 32 μg/mL via the generation of intracellular reactive oxygen species. By enabling specific therapies and improving our understanding of intricate biological processes at the nanoscale, these materials have the potential to completely transform the biomedical field. Our findings suggest the involvement of a working mechanism in transferring electrons between the conductance band of ZCQDs and the acidic protons of N, to produce the oxidized form NM for photoluminescence quenching of ZCQDs.

具有可调光学特性的功能化碳量子点广泛应用于传感器应用。在这项研究中，碳量子点是在水介质中通过与必要的反应性官能团的一步水热反应由锯叶榉叶（ZCQD）合成的。对合成的 ZCQD（平均尺寸，3-7 nm）进行了表征并确认其含有羟基/胺和羧酸官能团。光致发光光谱分析表明，在去离子水和老年人血浆样品中添加不同浓度的去甲肾上腺素（NM）后，ZCQD 的荧光强度急剧下降。我们开发的策略可以在去离子水和老年人血浆样本中检测 NM，检测限分别为 7.96 和 86.2 nM。有趣的是，傅里叶变换红外光谱在1660 cm ^-1处发现了一个新峰，证实了NM中酮基(C=O)基团的形成。此外，在 C 1s 和 O 1s 解卷积 X 射线光电子能谱中观察到显着的峰位移。带隙计算还揭示了 NM 和 ZCQD 之间的显着相互作用。研究了 ZCQD 在大肠杆菌和金黄色葡萄球菌中的抗菌活性，并在 32 μg/mL 的半数最大抑制浓度下通过产生细胞内活性氧在金黄色葡萄球菌中观察到了有效活性。通过实现特定的疗法并提高我们对纳米尺度复杂生物过程的理解，这些材料有可能彻底改变生物医学领域。我们的研究结果表明，ZCQD 的导带和 N 的酸质子之间的电子转移涉及一种工作机制，以产生用于 ZCQD 光致发光猝灭的氧化形式 NM。