One-pot synthesis of gold nanoclusters with bright red fluorescence and good biorecognition abilities for visualization fluorescence enhancement detection of E. coli.

A facile one-pot strategy was developed for the synthesis of lysozyme functionalized fluorescence gold nanoclusters (AuNCs). The lysozymes added to reduce Au(3+) ions and stabilize the AuNCs during the synthesis were coated on the AuNCs surface and retained their specific recognition ability for bacteria such as Escherichia coli (E. coli). Based on such ability, these AuNCs were specifically attached onto the surface of E. coli, which resulted in great red fluorescence enhancement. Nevertheless, the bovine serum albumin (BSA) stabilized AuNCs could not recognize E. coli and no fluorescence enhancement was observed. Upon the addition of E. coli, the red fluorescence intensity of lysozyme-AuNCs was enhanced linearly over the range of 2.4×10(4) -6.0×10(6) CFU/mL of E. coli with high sensitivity (LOD=2.0×10(4) CFU/mL, S/N=3). The visualization fluorescence evolution may enable the rapid and real-time detection of bacteria. This study may be extended to other functional proteins such as antibody, enzyme, and peptide functionalized nanoclusters while retaining the bioactivity of coating proteins and find wide applications in the fields of biochemistry and biomedicine.