Entacapone detection by a GOQDs-molecularly imprinted silica fluorescent chemical nanosensor

A sensitive fluorescent chemical nanosensor for the detection of entacapone (EN) in pharmaceutical samples is introduced. EN is a nitrocatechol drug that functions as a selective and reversible inhibitor of catechol-O-methyl transferase and is widely prescribed in the treatment of Parkinson disease. Molecularly imprinting technology and graphene oxide quantum dots (GOQDs) were employed in designing the EN fluorescent nanosensor. GOQDs were embedded into an inorganic polymer while the imprinting process occurred. The synthesized GOQDs-embedded silica molecularly imprinting polymer (SMIP) showed strong fluorescent emission at 450 nm by exciting at 360 nm. The fluorescence intensity of GOQDs-embedded SMIP was quenched effectively by adsorption of EN as a template molecule. The quenching corresponded to EN concentration in a linear range of at least 0.40-6.00 M with a limit of detection of 0.31 M. The designed chemical nanosensor was successfully applied to the analysis of entacapone in some pharmaceutical tablets also containing carbidopa and levodopa (RSD 3.8%).