pH Nanosensor Using Electronic Spins in Diamond
pH Nanosensor Using Electronic Spins in Diamond
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DOI：
10.1021/acsnano.9b05342
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发表时间：
2019-10-01
期刊：
影响因子：
17.1
通讯作者：
Igarashi, Ryuji
中科院分区：
文献类型：
--
作者：
Fujisaku, Takahiro;Tanabe, Ryotaro;Igarashi, Ryuji
纳米尺度的测量提供了对纳米世界的洞察。例如，细胞内pH的纳米时空分布受多种生物过程的调控。然而，目前还没有一种通用的方法来制备纳米级的pH传感器。在这里，为了赋予pH敏感功能，我们通过在含有氮空位中心(NV中心)的荧光纳米钻石(FND)上涂覆一层离子化学层来定制FND的表面性质。经表面羧基修饰的纳米金刚石中NV中心电子自旋的纵向弛豫时间T-1在pH 3~7之间与环境pH有关，而在pH 7~11之间与环境pH无关。因此，单个羧化纳米钻石颗粒在显微图像中作为纳米pH计工作，直接测量纳米局部pH环境。此外，通过在FND表面覆盖一层多半胱氨酸层，改变了FND的pH依赖性，聚半胱氨酸层含有大量具有较高pK(A)的硫醇基团。聚半胱氨酸包裹的纳米钻石在pH 7-11之间具有pH依赖性。在重水(D2O)缓冲液中也观察到了FND的pH依赖性。这表明pH依赖不是由H-1核自旋涨落引起的磁噪声引起的，而是由离子交换引起的电噪声引起的。通过我们的方法，通过根据目标生物现象适当地改变离子层，可以潜在地控制纳米金刚石pH传感器的敏感pH范围。
Nanoscale measurements provide insight into the nano world. For instance, nanometric spatiotemporal distribution of intracellular pH is regulated by and regulates a variety of biological processes. However, there is no general method to fabricate nanoscale pH sensors. Here, we, to endow pH-sensing functions, tailor the surface properties of a fluorescent nanodiamond (FND) containing nitrogen-vacancy centers (NV centers) by coating the FND with an ionic chemical layer. The longitudinal relaxation time T-1 of the electron spins in the NV centers inside a nanodiamond modified by carboxyl groups on the particle surface was found to depend on ambient pH between pH 3 and pH 7, but not between pH 7 and pH 11. Therefore, a single particle of the carboxylated nanodiamond works as a nanometer-sized pH meter within a microscopic image and directly measures the nanometric local pH environment. Moreover, the pH dependence of an FND was changed by coating it with a polycysteine layer, which contains a multitude of thiol groups with higher pK(a). The polycysteine-coated nanodiamond obtained a pH dependence between pH 7 and pH 11. The pH dependence of the FND was also observed in heavy water (D2O) buffers. This indicates that the pH dependence is not caused by magnetic noise induced by H-1 nuclear spin fluctuations, but by electric noise induced by ion exchanges. Via our method, the sensitive pH range of the nanodiamond pH sensor can potentially be controlled by changing the ionic layer appropriately according to the target biological phenomena.