fluorometric determination of lamotrigine using folic acid functionalized nitrogen and sulfur graphene quantum dots and silver nanoparticles coated with glycine and cysteine

Abstract: lamotrigine (ltg) is an antiepileptic drug that has been successfully applied in the treatment of epilepsy in adults and children over two years old as well as bipolar disorder. however, over-dose consumption of lamotrigine may result in the side effects such as the enhancement of suicide risk, a decrease in red blood cells, and an increase in allergic reactions. thus, significant demand has been raised for the development of new and rapid methods for the quantification of ltg in biological samples [1]. for monitoring drugs, metal nanoparticles and graphene quantum dots have been recognized as effective fluorescent nanoprobe [2, 3]. thus, in this study, a sensitive fluorometric method for the determination of lamotrigine has been developed using folic acid functionalized with sulfur and nitrogen graphene quantum dots (fa-s, n-gqds) and silver nanoparticles coated with cysteine and glycine. the fluorescence emission of fa-s, n-gqds at 493 nm decreases in the presence of the silver nanoparticles coated with cysteine and glycine due to forrester's resonant energy transfer mechanism (fret), however, the addition of lamotrigine to this system resulted in the retrieval of the fluorescence emission. this phenomenon can be related to the formation of the hydrogen bond between the functional group of drug and glycine and cysteine groups of silver nanoparticles followed by the release of fa- s, n-gqds surface. under optimal conditions, a linear relationship was obtained between the analytical signal and the concentration of lamotrigine in the range of 0.01-3.0 μm with a detection limit of 0.002 μm for the lamotrigine. the intra- and inter-day relative standard deviations at the 0.5 μm level of lamotrigine (n = 5) were 2.1 and 3.4%, respectively. the method was successfully utilized for the determination of lamotrigine in urine and serum samples.