Dopamine and tyrosine are essential biomolecules which play a key role in human metabolism. Tyrosine is an important precursor of thyroid hormones, dopamine, adrenaline, and other hormones that are used to establish and maintain a proper balance in humans . Hypothyroidism, hypochondria, and dementia are all caused by a lack of tyrosine. Dopamine belongs to the catecholamine family and is formed in the brain by dopaminergic neurons . Dopamine is a key signal-transmission component between neurons because it is linked to the majority of important human body functions like motor control, reward, motivation, and cognition [3–6]. Low levels of dopamine and tyrosine in the blood, as well as the death of dopaminergic neurons in the brain, have been linked to a range of significant neurological illnesses, including Parkinson's disease, psychosis, and attention deficit hyperactivity disorder (ADHD) drug addiction [6, 7]. To solve this problem, several studies have described novel approaches for detecting dopamine and tyrosine in a highly sensitive and selective manner, which might be utilized to identify dopamine and tyrosine-related neurological illnesses promptly [8–10].
Because of its short detection time and cost efficiency, the electrochemical sensing approach is recognized as one of the most effective approaches for dopamine and tyrosine detection among the different existing methods such as ELISA, colorimetric methods, Raman, and HPLC. [11–14]. Dopamine and tyrosine are redox-active chemicals that may be reduced or oxidized at different potentials, and their electrical characteristics can be used to detect their presence in a sample (usually human blood). The use of an electrochemical dopamine and tyrosine detection approach is challenging due to signal interference from other biological molecules (e.g., uric acid (UA), ascorbic acid (AA), and catecholamine molecules). Signal interference might greatly limit the sensitivity of dopamine detection since the reduction and oxidation potentials of these biological substances allegedly coincide with those of dopamine [15–17]. Furthermore, the electrochemical sensitivity of dopamine is still lower than that of other traditional techniques like HPLC and ELISA, which is a substantial hurdle to overcome before this approach can be utilized to detect accurate levels of dopamine . By functionalizing electrode surfaces or introducing other types of conductive materials, several attempts have been made to overcome the issues of selectivity and sensitivity.
Graphene, a two-dimensional (2D) honeycomb structure made up of pure carbon molecules, has been widely exploited in different scientific fields, including batteries, display panels, solar cells, and even biological applications [19–22]. Furthermore, graphene derivatives have been shown to exhibit notable dopamine-detection properties , which are principally owing to – and electrostatic interactions between the graphene oxides' surfaces. Various graphene-derivative-modified electrodes have been created to increase the performance of dopamine biosensors, including graphene/glassy carbon electrode (GCE), graphene–gold nanoparticles/GCE, TiO2–graphene/GCE, and GO/GCE electrodes [24–27]. One of the most intriguing carbonaceous compounds is graphene, a one-layer thick sheet with exceptional optical, thermal, and electrical characteristics. The discovery of porous graphene oxide (PGO), a type of graphene-oxide sheet with numerous hydroxyl groups and a porous surface , has the potential to improve the electrostatic interaction between the PGO and the analytes while also facilitating electron transfer between the molecules and the underlying electrode substrates .
Among the various binary compounds of tin chalcogenides, tin sulphides are well studied or explored owing to adaptable chemical nature and can be fabricated into hybrids, composites, non-toxic nature etc. hence they are widely used in energy storage devices, solar cells and optoelectronic devices. Despite this, the electrochemical procedure produces substantial capacity fading in tin sulphides due to the high-volume change. [14–16]. Because these matrices can greatly promote electron/ion transfer and effectively accommodate cycle-induced stress/strain of SnS, the electrochemical performance of tin sulphide has recently been improved by grafting nanosized tin sulphide into various types of carbon matrices (e.g., carbon spheres, amorphous carbon, macroporous carbon, carbon nanotubes, or graphene) [17–23]. Despite considerable gains in gravimetric capacity and cycle performance, the nanostructure of these composites, in combination with the low tap density of carbon matrix, can restrict volumetric capacity [24, 25]. Furthermore, the creation of these composites typically involves severe conditions or sophisticated synthesis, both of which are costly to industry. As a result, achieving a simple, scalable synthesis of tin sulphide-based graphene materials with superior volumetric storage remains a major challenge.
We used a facile hydrothermal method to create a novel graphene Oxide/ SnS2 (GO-SnS2) composite. SnS2 quantum dots are tightly supported on porous graphene oxide (PGO) in the composite, forming a primary microstructure and then assembling into a secondary nanostructure. The tap density of the nanostructured SnS2 and PGO hybrid is very high. The combination of SnS2 quantum dots and PGO nanosheets inside nanosized building blocks can not only improve overall electron/ion transport, but also efficiently insert SnS2 volume change and provide strong structural stability to the composite. As a result, the tightly compacted GO-SnS2 quantum dots show high, fast, and stable dopamine electrochemical detection. Thus, the prepared GO-SnS2 quantum dots were found to be exhibiting superior electrochemical performance, combined with its simple scalable synthesis, makes it a promising candidate for practical application.