Single-Ligand Modulated Size-Dependent Multi-Color Au/Os Nanoclusters for Multi-Analyte Detection

The development of nanoclusters (NCs) capable of multicolor emissions for simultaneous detection of multiple analytes has aroused tremendous interest. However, the current methods for synthesizing NCs with multicolor emissions mainly depend on a multiple ligand strategy, which not only compromises the stability of the NCs but also alters their physicochemical properties. Herein, we propose a novel strategy for designing single-ligand capped bimetallic Au/Os NCs with multicolor fluorescence by adjusting the size of the NCs. This size-controlled, single-ligand encapsulation strategy not only enhances their stability and compatibility but also ensures uniformity in their physicochemical properties, thereby overcoming limitations inherent in multiligand systems. By meticulously modulating the reaction parameters, we achieved precise tuning of the NCs size, resulting in the synthesis of multicolor fluorescent NCs displaying blue (465 nm), green (507 nm), and yellow (560 nm) emissions. These multicolor Au/Os NCs were then incorporated into an array system for the differentiation of tetracyclines (TCs) by virtue of their interaction with TCs through the inner filter effect (IFE). Finally, each TC elicited a unique fluorescent response, which was subsequently analyzed by principal component analysis. The sensor array has been successfully employed for detection of TCs in milk, urine, and water, demonstrating its practical application potential. The strategy developed in this work holds great promise for the development of multicolor NCs.