Bifunctional carbon dots have shown a large amount of potential in bioimaging and antioxidation applications. However, the hydrothermal method for the preparation of bifunctional carbon dots requires a high energy input and an expensive setup. Moreover, this method breaks down sensitive compounds in the raw materials and could decrease the antioxidation ability of the resulting carbon dots. Here, phenolic extracts of coffee bean shells were used to prepare carbon dots via a cheap, energy-saving, mild molecular aggregation method. The as-prepared carbon dots were characterized by TEM, HPLC, XPS and Raman spectroscopy. The carbon dots had a diameter ranging from 1 to 5 nm and mainly contained three kinds of phenolic compounds including 3,4,5-trihydroxybenzoic acid, 3,4-dihydroxybenzaldehyde and 3,4-dihydroxybenzoic acid. The carbon dots demonstrated a strong antioxidation capacity, which was comparable to the commercially available butylated hydroxytoluene. The EC₅₀ of the carbon dots was 110 μg mL⁻¹. The carbon dots had a pH-/excitation-dependent fluorescence. The as-prepared carbon dots also showed anti-bleaching fluorescence, which was better than that of the commercially available 4′,6-diamidino-2-phenylindole. Based on this finding, the excellent biocompatibility of carbon dots enabled them to be successfully used for banana storage and imaging both cancer cell nuclei and tumors in vivo.

中文翻译：

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从生物质材料中寻求价值：通过分子聚集法制备咖啡豆壳衍生的荧光碳点，以用于抗氧化和生物成像应用†

在生物成像和抗氧化应用中，双功能碳点已显示出大量潜力。然而，用于制备双功能碳点的水热法需要高能量输入和昂贵的装置。而且，该方法分解了原料中的敏感化合物，并可能降低所得碳点的抗氧化能力。在这里，咖啡豆壳的酚类提取物用于通过碳纳米管制备碳点。一种廉价，节能，温和的分子聚集方法。所制备的碳点通过TEM，HPLC，XPS和拉曼光谱法表征。碳点的直径为1至5nm，并且主要包含三种酚类化合物，包括3,4,5-三羟基苯甲酸，3,4-二羟基苯甲醛和3,4-二羟基苯甲酸。碳点具有很强的抗氧化能力，可与市售的丁基化羟基甲苯媲美。碳点的EC ₅₀为110μgmL ^-1。碳点具有pH /激发相关的荧光。所制备的碳点还显示出抗漂白荧光，其比市售的4'，6-二mid基-2-苯基吲哚更好。基于这一发现，碳点的出色生物相容性使它们能够成功用于香蕉存储以及体内癌细胞核和肿瘤的成像。