De novo design of a photoluminescent sensor for baicalin detection via regulating molecule-like charge transfer of gold nanocluster

Selective and sensitive detection of bioflavonoid glycosides remains a great challenge because the coexistence of their analogues in real samples will produce serious interference. Herein, baicalin was selected as an example to demonstrate that precise control of the molecule-like photoinduced charge transfer (PCT) behavior of gold nanoclusters (AuNCs) can be served as a new and efficient way to develop high-performance sensors for bioflavonoid glycosides detection. After a rational design was made using the prediction of a classical charge transfer theory, an AuNC-based photoluminescent sensor was constructed for baicalin determination. Such a sensor not only displayed high specificity toward baicalin in the presence of baicalein and other analogues of baicalin, but also could be applied in the analysis of baicalin content in the extract of Scutellaria baicalensis. Notably, the baicalin-involved PCT process was solidly revealed by steady and transient spectroscopic measurements for the first time. This study will inspire further work on sensors for the discrimination and screening of biomolecules from their analogues employing PCT techniques.