Sensitive Voltammetric Detection of Melatonin in Pharmaceutical Products by Highly Conductive Porous Graphene-Gold Composites

Abstract

This work presents a novel melatonin sensor based on unfunctionalized macroporous graphene networks decorated with gold nanoparticles for the differential pulse voltammetric detection of melatonin in pharmaceutical products. Highly porous graphene structures were prepared by metallic template-assisted chemical vapor deposition, and their active surface area and electrocatalytic activity were improved by electrochemical deposition of gold nanoparticles (50−250 nm) on their struts. The graphene-gold electrodes present a highly sensitive performance toward electro-oxidation of melatonin with a wide linear range of 0.05−50 μM, a low detection limit of 0.0082 μM (3σ/m), and a significant sensitivity of 16.219 μA μM −1 cm −2 . Therefore, the performance of the sensor regarding the obtained figures of merit is better than many other electrodes utilized for melatonin detection. The electrochemical active surface area of the glassy carbon electrode was multiplied by 18, and the high conductivity of gold-graphene composites and their synergistic catalytic effect lowered electron transport resistance by 87%. Moreover, long-term signal stability for about 14 days, acceptable reproducibility (relative standard deviation (RSD) of 4.70%), repeatability (RSD of 0.14%), and selectivity of the electrodes with various interfering materials are demonstrated. The valid potential application of the sensors for the determination of melatonin in pharmaceutical samples is shown.

Ultrafast Graphitization and Reduction of Spongy Graphene Oxide by Low-Energy Electromagnetic Radiation to Boost the Performance and Stability of Carbon-Based Supercapacitors

“…25 Ruoff et al 31 have reported that during microwave irradiation at 1100 W for 40 s, overlapped and crumpled RGO sheets are formed. Similar to CVD-grown GFs, 1,32 vertically standing graphene nanoflakes with sharp edges are observed (Figure 1e). It is noteworthy that thermal annealing at 800 °C for 4 h does not significantly change the interlinked structure of the TrGO (TA-GF) (Figure 1d,h).…”

A graphene-based electrochemical flow analysis device for simultaneous determination of dopamine, 5-hydroxytryptamine, and melatonin

“…Based on eqn (1), the electroactive surface area of AuNPs@Gr (0.49 cm 2 ) was found to be increased by 48.5% compared to Gr (0.33 cm 2 ), which was similar to the results of previous studies. 20 The results suggested that the improvement in the detection of DA, 5-HT, and MEL was the consequence of the increment in the catalytically active sites of the AuNPs@Gr electrode.…”

“…† Among them, the coarser particles are mainly formed in high-energy regions, such as edges or wrinkles of the graphene sheets, which have higher driving forces to promote the formation of gold nanoparticles. 20 EDS tests were performed to evaluate the detailed elemental composition of the modified electrode. The distribution of carbon and gold within the modified electrode can be observed in element mapping images (see Fig.…”

“…19 The healthy MEL level range in the human body is found from 0.01 µg L −1 in light to 0.20 µg L −1 in darkness. 20 Deviating from the healthy range of MEL levels may cause disordered sleep and circadian rhythms, which are the prominent features of MDD. 21 MEL is also an important target for the treatment of MDD.…”

A Sensitive Electrochemical Sensor Based on Sonogel-Carbon Material Enriched with Gold Nanoparticles for Melatonin Determination

“…The affordable cost and eco-friendly preparation of the SNGCE material support its investigation as a sensing element in the development of an electrochemical sensor for melatonin. The tailoring and design of the proposed electrochemical sensor was achieved by exploring the well-known properties of gold nanoparticles for electrochemical sensing applications [ 30 , 31 ]. The prepared sensing materials were further investigated in terms of their electrochemical and electroanalytical properties and performance toward melatonin determination.…”