Ultrasmall gold nanoclusters (NCs) have been engineered as a new kind of functional material due to their excellent photoluminescence properties. However, the synthesis of highly luminescent water-soluble nanoclusters with near-infrared (NIR) emission remains limited. Herein, we developed a pH-regulated strategy to facilitate the construction of self-assemblies with enhanced luminescence based on aggregation-induced emission (AIE) strategy. Using 2-mercaptobenzoic acid (MBA) as reductant and stabilizer, the original weakly luminescent AuNCs exhibited intense emission by adjusting pH controllably. The formation of compact organized nanostructures could effectively restrict the rotation and vibration of capping ligands by non-covalent interactions, which reduced the nonradiative relaxation from excited states and finally improved the emission properties of AuNCs. Moreover, the assemblies possess many intriguing features including bright NIR luminescence and excellent biocompatibility, which could be used as luminous probes in biological molecules sensing (tyrosinase (TYR) and dopamine (DA)) and promising candidates for cell imaging. This study provides a simple and feasible strategy for developing metal NCs-based smart optical materials in the field of bioscience.

超小型金纳米团簇 (NCs) 因其优异的光致发光特性而被设计为一种新型功能材料。然而，具有近红外（NIR）发射的高发光水溶性纳米团簇的合成仍然有限。在此，我们开发了一种 pH 调节策略，以促进基于聚集诱导发光 (AIE) 策略的增强发光自组装的构建。使用 2-巯基苯甲酸 (MBA) 作为还原剂和稳定剂，原始的弱发光 AuNCs 通过可控调节 pH 值表现出强烈的发光。紧密有序的纳米结构的形成可以通过非共价相互作用有效地限制封端配体的旋转和振动，这减少了激发态的非辐射弛豫，最终改善了 AuNC 的发射特性。此外，该组件具有许多有趣的特性，包括明亮的 NIR 发光和出色的生物相容性，可用作生物分子传感（酪氨酸酶 (TYR) 和多巴胺 (DA)）中的发光探针，并有望用于细胞成像。该研究为在生物科学领域开发基于金属 NCs 的智能光学材料提供了一种简单可行的策略。