Department of Chemistry, Beijing Normal University, Beijing, 100875, China.
Nanoscale. 2015 Jul 21;7(27):11727-33. doi: 10.1039/c5nr02007g. Epub 2015 Jun 23.
Smart functional nanomaterials colorimetrically responsive to all-pH and a wide temperature range are urgently needed due to their widespread applications in biotechnology, drug delivery, diagnosis and optical sensing. Although graphene quantum dots possess remarkable advantages in biological applications, they are only stable in neutral or weak acidic solutions, and strong acidic or alkaline conditions invariably suppress or diminish the fluorescence intensity. Herein, we report a new type of water-soluble, multicolor fluorescent graphene quantum dot which is responsive to all-pH from 1 to 14 with the naked eye. The synthesis was accomplished by electrolysis of the graphite rod, followed by refluxing in a concentrated nitric and sulfuric acid mixed solution. We demonstrate the novel red fluorescence of quinone structures transformed from the lactone structures under strong alkaline conditions. The fluorescence of the resulting graphene quantum dots was also found to be responsive to the temperature changes, demonstrating their great potential as a dual probe of pH and temperature in complicated environments such as biological media.
由于其在生物技术、药物输送、诊断和光学传感等领域的广泛应用，急需对所有 pH 值和宽温度范围都具有响应的智能功能纳米材料进行比色检测。尽管石墨烯量子点在生物应用中具有显著的优势，但它们仅在中性或弱酸性溶液中稳定，而强酸性或碱性条件总是会抑制或减弱荧光强度。在此，我们报告了一种新型的水溶性、多色荧光石墨烯量子点，其对 pH 值从 1 到 14 具有肉眼可见的响应。该合成通过石墨棒的电解，然后在浓硝酸和硫酸混合溶液中回流来完成。我们证明了在强碱性条件下，醌结构从内酯结构转化而来的新型红色荧光。还发现所得石墨烯量子点的荧光对温度变化有响应，表明它们在生物介质等复杂环境中作为 pH 和温度的双探针具有很大的潜力。
