Pyrene-Functionalized Graphene Oxide for Fluorescent Detection of Berberine

A ternary system (GOB-SDS) was established for the ratiometric fluorescent detection of Berberine in an aqueous solution. In this ternary system (GOB-SDS), the fluorescence reporter B was grafted onto the edges of graphene oxide (GO) through the amido bond (C(═O)NH). In the absence of sodium dodecyl sulfate (SDS), the fluorescence of B could be quenched via fluorescence resonance energy transfer (FRET) due to the strong π–π stacking interaction between B and GO. With the addition of SDS, the formation of a B-SDS micelle weakened the interaction between GO and B, leading to the recovery of B's fluorescence. Then, Berberine was added. The easy formation of Berberine-SDS instead of B-SDS was due to the strong electrostatic interaction between Berberine and SDS, and B's fluorescence emission at 393 nm was again quenched by GO. Meanwhile, the AIE behavior of Berberine (fluorescence emission at 536 nm) was enhanced. Thus, a ratiometric fluorescent sensor (F536 nm/F393 nm) was achieved to realize the sensitive detection of Berberine. The characteristics of the obtained GOB-SDS and the detection mechanism of Berberine were fully studied using various methods. In addition, the high stability, selectivity, sensitivity, anti-interference, and sustainability of the ternary system toward Berberine were also demonstrated; the ratiometric fluorescent Berberine sensor showed a good linear range from 0 to 8.90 μM (0 to 3.00 μg/mL) with a detection limit of 23.4 nM (8.17 ng/mL). Furthermore, this system could be used to detect Berberine in real drugs with a low background, and a combination of this system with a smartphone could be applied for on-site analysis of Berberine.