Pattern recognition of melatonin using stochastic sensors

Abstract

Two stochastic sensors based on reduced graphene oxide (rGO) decorated with TiO₂ (rGO-TiO₂) and graphene decorated with TiO₂ and gold nanoparticle (rGO-TiO₂–Au) pastes were designed, and characterized for the pattern recognition of melatonin in pharmaceutical and biological samples. The pastes were modified with a solution of a complex of protoporphyrin IX with cobalt. The best sensitivity (8.95 × 10⁴ s⁻¹ μg⁻¹ mL⁻¹) was obtained when the sensor based on rGO-TiO₂–Au was used. The same limit of determination (2.32 × 10⁻⁹ μg mL⁻¹) was determined for both stochastic sensors. The proposed method was reliably used for the pattern recognition and quantitative determination of melatonin in biological fluids, such as breast milk and whole blood, infant milk formulas, and pharmaceutical products. Recoveries higher than 99.00% were recorded for both stochastic sensors when used for pattern recognition and quantitative assay of melatonin in biological (breast milk and whole blood samples), food (infant milk formulas) and pharmaceutical samples.