Investigating the Effect of Silver Nanoparticles on the Fluorescence Intensity of Bambuterol and its Active Metabolite Terbutaline Using FRET.

Silver nanoparticles (AgNPs) were found to significantly quench the fluorescence of bambuterol hydrochloride (BAM) and its active metabolite terbutaline sulfate (TER). The intrinsic fluorescence intensity of each of BAM (at 264/292 nm) and TER (at 276/306 nm) decreased by the gradual addition of AgNPs. Quenching of the steady state fluorescence of BAM and TER probably resulted from the energy transfer to the photo-excited state of AgNPs. The estimated Stern-Volmer quenching constant at several temperature settings proved that the quenching mechanism of the two drugs was dynamic quenching in case of BAM while it was static quenching in case of TER. The number of binding sites, binding constants, and corresponding thermodynamic parameters depending on the interaction system were estimated at 293, 313, and 333 °K and the results obtained were interpreted.