Luminescent, bimetallic AuAg alloy quantum clusters in protein templatesElectronic supplementary information (ESI) available: XPS, SEM EDAX, UV-Vis, PL and FTIR measurements. See DOI: 10.1039/c2nr30729d

• Main Authors: Mohanty, Jyoti Sarita, Xavier, P. Lourdu, Chaudhari, Kamalesh, Bootharaju, M. S, Goswami, N, Pal, S. K, Pradeep, T
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c2nr30729d

We report the synthesis of luminescent AuAg alloy quantum clusters (QCs) in bovine serum albumin (BSA), for the first time, with experimentally determined atomic composition. Mixing of the as-synthesized protein-protected Au and Ag clusters resulted in the formation of alloy AuAg clusters within the BSA. Mass spectrometric analysis of the product of a 1 : 1 molar ratio reaction mixture of Au QC @BSA and Ag QC @BSA suggested that the alloy clusters could be Au 38− x Ag x @BSA. Further analyses by standard techniques revealed that the alloy cluster core of ∼1.2 nm diameter is composed of nearly zero valent Au and Ag atoms that exhibit distinctly different steady state and time resolved excited state luminescence profiles compared to the parent clusters. Tuning of the alloy composition was achieved by varying the molar ratio of the parent species in the reaction mixture and compositional changes were observed by mass spectrometry. In another approach, mixing of Au 3+ ions with the as-synthesized Ag QC @BSA also resulted in the formation of alloy clusters through galvanic exchange reactions. We believe that alloy clusters with the combined properties of the constituents in versatile protein templates would have potential applications in the future. The work presents interesting aspects of the reactivity of the protein-protected clusters. Luminescent AuAg alloy quantum clusters (QCs) were synthesized through QC-QC interaction and galvanic exchange, revealing interesting reactivity of protein-protected clusters.