A green strategy for fabrication of biobased reduced nanographene oxide (r-nGO) was developed. Cellulose derived nanographene oxide (nGO) type carbon nanodots were reduced by microwave assisted hydrothermal treatment with superheated water alone or in the presence of caffeic acid (CA), a green reducing agent. The carbon nanodots, r-nGO and r-nGO-CA, obtained through the two different reaction routes without or with the added reducing agent, were characterized by multiple analytical techniques including FTIR, XPS, Raman, XRD, TGA, TEM, AFM, UV–vis, and DLS to confirm and evaluate the efficiency of the reduction reactions. A significant decrease in oxygen content accompanied by increased number of sp² hybridized functional groups was confirmed in both cases. The synergistic effect of superheated water and reducing agent resulted in the highest C/O ratio and thermal stability, which also supported a more efficient reduction. Interesting optical properties were detected by fluorescence spectroscopy where nGO, r-nGO, and r-nGO-CA all displayed excitation dependent fluorescence behavior. r-nGO-CA and its precursor nGO were evaluated toward osteoblastic cells MG-63 and exhibited nontoxic behavior up to 200 μg mL^–1, which gives promise for utilization in biomedical applications.

中文翻译：

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通过微波辅助转化纤维素减少纳米氧化石墨烯的绿色策略

开发了一种用于制造生物基还原纳米氧化石墨烯（r-nGO）的绿色策略。单独使用过热水或在绿色还原剂咖啡酸（CA）的存在下，通过微波辅助水热处理对纤维素衍生的纳米氧化石墨烯（nGO）型碳纳米点进行还原。通过两种不同的反应途径获得的碳纳米点r-nGO和r-nGO-CA，无论是否添加还原剂，都通过多种分析技术进行了表征，包括FTIR，XPS，拉曼，XRD，TGA，TEM，AFM，用UV-vis和DLS确认并评估还原反应的效率。氧含量显着下降，同时sp ²数量增加在这两种情况下均证实了杂化的官能团。过热水和还原剂的协同作用导致最高的C / O比和热稳定性，这也支持更有效的还原。通过荧光光谱法检测到有趣的光学性质，其中nGO，r-nGO和r-nGO-CA均显示出与激发有关的荧光行为。对成骨细胞MG-63评估了r-nGO-CA及其前体nGO，它们显示出高达200μgmL ^–1的无毒行为，这为在生物医学应用中使用提供了希望。