From intermediate capture to functional cluster construction: Synthesis of silver clusters and their Br−/I− sensing applications

Developing advanced fluorescent materials with near-infrared emission and long Stokes shifts is crucial for modern biosensing and environmental monitoring. Silver sulfide nanoclusters, with their unique optical properties and biocompatibility, have emerged as a promising candidate in this field. A research team led by Prof. Huayan Yang from Shenzhen University, China, has recently reported a significant advance in the synthesis and application of silver sulfide nanoclusters for ion sensing. The researchers successfully synthesized highly stable Ag₅₆ nanoclusters using 4-vinylbenzoic acid (p-VBA) and tert-butyl mercaptan as ligands. This synthesis method, which involves precise control of reaction parameters such as temperature and solvent, not only achieved high-yield production but also allowed the capture of key intermediates Ag₂₀, Ag₃₁, Ag₃₂, Ag₃₀-bpbenz and Ag₃₁-bpe. These nanoclusters exhibit a unique fluorescence aggregation redshift phenomenon due to π–π interactions in the ligands, making them ideal for sensing applications.

The team also developed a fluorescence-enhanced sensor based on Ag₅₆ nanoclusters capable of detecting trace amounts of bromide (Br⁻) and iodide (I⁻) ions in water samples with detection limits as low as 85 and 105 nM, respectively. Operating in the near-infrared range, this sensor offers advantages such as low background interference and high tissue penetration, which are beneficial for bio-detection and in vivo diagnostics.

The team published their research article in the journal Polyoxometalates on February 25, 2025.

Prof. Huayan Yang, who works at the Shenzhen Key Laboratory of Nano-Biosensing Technology, Shenzhen University, highlighted the significance of this work: "Our study provides new insights into the controlled synthesis of silver sulfide nanoclusters and their potential applications in ion sensing. The ability to capture reaction intermediates and manipulate their optical properties through ligand engineering opens up new possibilities for the development of highly sensitive and selective sensors."

The Ag₅₆ nanoclusters, with their long Stokes shift and near-infrared emission, represent a significant step forward in the field of fluorescent sensing. The research team expects that these findings will inspire further exploration into the design and application of silver sulfide nanoclusters for various sensing technologies.

Other contributors to this work include Zhixun Zhang, Juefei Dai, Cheng-Cheng Feng, Chuanhua Shi, Lebing Zhou, Xianyong Yu, Chao Yang, and Xueji Zhang from Shenzhen University and Hunan University of Science and Technology. This work was supported by the Shenzhen Science and Technology Program (No. KQTD20221101093605019), Medical-Engineering Interdisciplinary Research Foundation of Shenzhen University (No. 2023YG001), Shenzhen Science and Technology Innovation Commission (No. JCYJ20220531101202005), and Shenzhen Key Laboratory of Nano-Biosensing Technology (No. ZDSYS20210112161400001).

About the Authors

Zhixun Zhang (co-first author), a master's degree candidate at Shenzhen University, focuses his research on the synthesis, structure, and properties of silver sulfide nanoclusters and their assembled materials.

Juefei Dai (co-first author), research assistant at Shenzhen University. He got his bachelor degree (2021) and master degree (2024) from Hunan University of Science and Technology. His research interesting focuses on the synthesis, structure, and properties of metal nanoclusters.

About Polyoxometalates

Polyoxometalates (POM) is a peer-reviewed, open-access and interdisciplinary journal, published quarterly by Tsinghua University Press, released exclusively on SciOpen. POM publishes original high-quality research papers and significant review articles that focus on cutting-edge advancements in polyoxometalates, and clusters of metals, metal oxides and chalcogenides. It is dedicated to exploring all topical areas, ranging from basic aspects of the science of polyoxometalates, and clusters of metals, metal oxides and chalcogenides to practical applications of such materials. The journal is indexed by Scoups and DOAJ.

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