A new "turn-on" fluorescent sensor based on gold quantum dots and silver nanoparticles for lamotrigine detection in plasma.

A simple and rapid method for the quantification of lamotrigine (LTG) was developed using 4-aminothiophenol-stabilized gold quantum dots (4-ATP-AuQDs) and amidosulfonic acid-capped silver nanoparticles (ASA-AgNPs) as a new fluorescence resonance energy transfer (FRET) probe. 4-ATP-AuQDs and ASA-AgNPs were synthesized and characterized by UV-Vis and fluorescence spectroscopy, and transmission electron microscopy. Since the emission spectra of 4-ATP-AuQDs have good overlaps with the absorption spectra of ASA-AgNPs, the fluorescence of the AuQDs was significantly quenched in the presence of AgNPs as a result of FRET. However, when LTG was added, a significant fluorescence enhancement was observed owing to the remarkable aggregation of ASA-AgNPs, which could take ASA-AgNPs away from 4-ATP-AuQDs. This method could selectively detect LTG with a detection limit of 4.0ngmL-1 in standard aqueous solution and good linearity was obtained over the range 0.02-0.5µgmL-1 (R=0.9989). The proposed method was successfully applied for the determination of LTG in spiked human plasma samples with a limit of detection of 0.3µgmL-1 and a linear range of 0.5-6.0µgmL-1. The method was also successfully applied to quantify LTG in real plasma samples from epileptic patients receiving LTG.