Fluorescence dynamics of gold nanoclusters (Au₉ and Au₂₅) are studied in the complex and crowded environment of a triblock co‐polymer (F127) hydrogel and inside cervical cancer cell, HeLa. In the hydrogel, spherical micelles of F127 remain immobilized with a hydrophobic core (PPO) and a hydrophilic corona (PEO) region. The fluorescence anisotropy decay suggests that the timescale of rotational relaxation in the hydrogel is similar to that in bulk water (viscosity ∼1 cP). From fluorescence correlation spectroscopy (FCS) it is inferred that the local viscosity in the hydrogel is 12 cP for Au₉ and 18 cP for Au₂₃. These results indicate that gold nanoclusters (AuNCs) localize in the corona region of the hydrogel. Evidently, frictions against rotation and translation are different inside the gel. It is suggested that rotation of the AuNCs senses the immediate water‐like “void” region while translation motion involves in‐and‐out movement of the AuNCs at the periphery of the gel. Finally, the gold nanoclusters are used for cell imaging and estimation of intracellular viscosity of HeLa cells.

中文翻译：

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使用荧光金纳米团簇研究共聚物水凝胶和HeLa细胞的粘度：荧光相关光谱和各向异性衰减。

研究了在三嵌段共聚物（F127）水凝胶和子宫颈癌细胞HeLa内部复杂且拥挤的环境中金纳米团簇（Au ₉和Au ₂₅）的荧光动力学。在水凝胶中，F127的球形胶束保持固定在疏水核（PPO）和亲水电晕（PEO）区域。荧光各向异性衰减表明，水凝胶中旋转弛豫的时间尺度与散装水中的旋转弛豫的时间尺度相似（粘度约为1 cP）。从荧光相关光谱法（FCS）推断，水凝胶中的局部粘度对于Au ₉为12 cP，对于Au ₂₃为18 cP。这些结果表明金纳米团簇（AuNCs）位于水凝胶的电晕区域。显然，凝胶内部旋转和平移的摩擦力是不同的。建议AuNCs的旋转感应到直接的水样“空隙”区域，而平移运动涉及AuNCs在凝胶外围的进出运动。最后，金纳米簇用于细胞成像和HeLa细胞的细胞内粘度估计。