Emissive bovine serum albumin-templated osmium nanoclusters: synthesis and optical characterization

Synthesis of new nanomaterials with unique optical properties is of great importance in different fields such as energy, material science, and biomedicine. Here, for the first time, we report the synthesis of the emissive osmium nanoclusters (OsNCs) using bovine serum albumin (BSA) as template and sodium borohydride as strong reducing agent. The as-synthesized emissive OsNCs had only 31 atoms, with deep-blue color emission with an emission maximum at 415 nm and a photoluminescence quantum yield (PLQY) of 2.5 %. The fluorescence emission of OsNCs could be attributed to the smaller number of atoms (31) in the as-synthesized OsNCs in this work. The optical characterization of the emissive OsNCs revealed that the fluorescence intensity was more sensitive to pH than with temperature of the solution. When pH was increased from 1-12, there was 6-fold increase in the emission intensity. We believe that the presented synthesis route as well as the results of this work could open new avenues to further investigate the OsNCs as new emissive nanomaterials and their potential applications in biomedical and energy fields.