Spectrofluorometric determination of berberine using a novel Au nanocluster with large Stokes shift

Berberine hydrochloride (BHC), a natural isoquinoline alkaloid, is widely applied as a an agent in traditional Chinese medicine. Almost all the traditional methods for BHC detection require complicated preprocessing steps or expensive instruments. In this article, we report a simple, rapid, sensitive, and selective method for BHC detection using fluorescent gold nanoclusters (F-AuNCs) as the fluorescent probe with a large Stokes shift of 237 nm. The F-AuNCs prepared with citrate-stabilized stannous chloride and hydrogen tetrachloroaurate(III) as raw materials in an aqueous medium display strong and stable fluorescence at 566 nm. When F-AuNCs are mixed with BHC, the fluorescence of F-AuNCs is effectively quenched. Under optimized conditions, this method allows sensitive and selective measurements of BHC in a concentration ranging from 1.0 x 10(-6) to 1.0 x 10(-4) mol L-1 with a detection limit of 7.5 x 10(-8) mol L-1, which is relatively low among reported spectral methods. This method provides excellent selectivity for the detection of BHC against inorganic anions and natural amino acids. In addition, the BHC content in two different types of berberine tablets was successfully determined by this method and the results showed high accuracy.