Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University , Dongchuan Road 500, Shanghai 200241, China.
Key Laboratory for Advanced Materials, Centre or computational Chemistry and Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology , 130 Meilong Road, Shanghai 200237, China.
ACS Appl Mater Interfaces. 2017 Oct 25;9(42):36596-36605. doi: 10.1021/acsami.7b11028. Epub 2017 Oct 13.
With a burst development of new nanomaterials for plasmon-free surface-enhanced Raman scattering (SERS), the understanding of chemical mechanism (CM) and further applications have become more and more attractive. Herein, a novel SERS platform was specially designed through electrochemical deposition of graphene onto TiO nanoarrays (EG-TiO). The developed EG-TiO nanocomposite SERS platform possessed remarkable Raman activity using copper phthalocyanine (CuPc) as a probe molecule. X-ray photoelectron spectroscopy measurement revealed that the chemical bond Ti-O-C was formed at the interface between graphene and TiO in EG-TiO nanocomposites. Both experimental and theoretical results demonstrated that the obvious Raman enhancement was attributed to TiO-induced Fermi level shift of graphene, resulting in effective charge transfer between EG-TiO nanocomposites and molecules. Taking advantage of a marked Raman response of the CuPc molecule on the EG-TiO nanocomposite surface as well as specific recognition of CuPc toward multiple telomeric G-quadruplex, EG-TiO nanocomposites were tactfully employed as the SERS substrate for selective and ultrasensitive determination of telomerase activity, with a low detection limit down to 2.07 × 10 IU. Interestingly, the self-cleaning characteristic of EG-TiO nanocomposites under visible light irradiation successfully provided a recycling ability for this plasmon-free EG-TiO substrate. The present SERS biosensor with high analytical performance, such as high selectivity and sensitivity, has been further explored to determine telomerase activity in stem cells as well as to count the cell numbers. More importantly, using this useful tool, it was discovered that telomerase activity plays an important role in the proliferation and differentiation from human mesenchymal stem cells to neural stem cells. This work has not only established an approach for gaining fundamental insights into the chemical mechanism (CM) of Raman enhancement but also has opened a new way in the investigation of long-term dynamics of stem cell differentiation and clinical drug screening.
随着用于无等离子体表面增强拉曼散射（SERS）的新型纳米材料的爆发式发展，对化学机制（CM）的理解和进一步的应用变得越来越有吸引力。在此，通过将石墨烯电化学沉积到 TiO 纳米阵列上（EG-TiO），专门设计了一种新型的 SERS 平台。使用铜酞菁（CuPc）作为探针分子，开发的 EG-TiO 纳米复合材料 SERS 平台具有显著的拉曼活性。X 射线光电子能谱测量表明，在 EG-TiO 纳米复合材料中，石墨烯和 TiO 之间形成了化学键 Ti-O-C。实验和理论结果均表明，明显的拉曼增强归因于 TiO 引起的石墨烯费米能级移动，从而导致 EG-TiO 纳米复合材料与分子之间的有效电荷转移。利用 CuPc 分子在 EG-TiO 纳米复合材料表面的明显拉曼响应以及 CuPc 对多种端粒 G-四链体的特异性识别，巧妙地将 EG-TiO 纳米复合材料用作 SERS 基底，用于端粒酶活性的选择性和超灵敏测定，检测限低至 2.07×10 IU。有趣的是，EG-TiO 纳米复合材料在可见光照射下的自清洁特性成功地为这种无等离子体 EG-TiO 基底提供了可回收能力。这种具有高分析性能的 SERS 生物传感器，如高选择性和灵敏度，已进一步用于测定干细胞中端粒酶的活性以及计数细胞数量。更重要的是，使用这种有用的工具，发现端粒酶活性在人骨髓间充质干细胞向神经干细胞的增殖和分化中起着重要作用。这项工作不仅建立了一种方法来深入了解拉曼增强的化学机制（CM），而且还为研究干细胞分化的长期动力学和临床药物筛选开辟了新途径。
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