Ratiometric fluorescence sensing of p-nitrophenol using dual-emission carbon dots-functionalized bovine serum albumin-templated Au nanoclusters

In this study, novel dual-emission Au nanoclusters (BSA@CDs-BSA-AuNCs) were developed via a two-step in-situ synthesis strategy. Step one, bovine serum albumin (BSA) doped carbon dots (BSA@CDs) covalently bound to BSA under the coupling effect of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to obtain BSA@CDs-functionalized BSA (BSA@CDs-BSA); step two, in-situ synthesis of Au nanoclusters using BSA@CDs-BSA as template was conducted and BSA@CDs-BSA-AuNCs with a size of 30 nm and two characteristic emission peaks at 450 and 675 nm confirmed to be attributed to BSA@CDs and BSA-templated AuNCs (BSA-AuNCs) respectively were fabricated, presenting an emission separation of 225 nm. The prepared nanoclusters were fully characterized. Notably, the two characteristic emission peaks both have been redshifted compared to the original BSA@CDs and BSA-AuNCs respectively, due to possible charge transfer occurred between BSA ligand and the above two fluorophores. Further, it has been applied to establish an original ratiometric fluorescence sensor for p-nitrophenol (p-NP) detection with excellent performance, which has not been reported in literatures.