Introduction

Cancer ranks as the most severe public health threat because it constitutes a permanent medical condition. Cancer has become the second most common cause of death, which follows cardiovascular disease as the leading cause. Chemotherapy represents a fundamental cancer treatment method in which doctors prescribe one or multiple medications to treat cancer through complete cancer elimination or cancer cell growth suppression [1,2]. The main factor determining drug quality control is testing various substances. Doxorubicin (DOX) serves as an anthracycline-based chemotherapy drug to treat multiple types of cancers and sarcomas, which include lung, breast, bladder, leukaemia, liver, head and neck cancers. The drug exerts its therapeutic action by binding to the DNA helix, thereby blocking transcription and replication in cancer cells via its anthracycline component [3-5]. The drug interacts with dissolved oxygen to generate reactive oxygen species that damage mitochondria. DOX produces several common chemotherapy side effects, which include nausea and vomiting, hair loss and weakened immunity, despite its high treatment effectiveness. The total cumulative dosage of DOX that a patient receives determines whether the drug will induce dangerous cardiotoxic side effects [6-8]. The procedure requires establishing specific medication dosages by monitoring DOX excretion and tracking drug concentrations in biological samples.

The detection of DOX has been achieved using various methods, including UV-Vis spectrophotometry [9], capillary electrophoresis [10], Raman spectroscopy [11] and high-performance liquid chromatography [12]. However, most of these techniques have numerous disadvantages, including high costs, large sample volumes, the need for highly qualified staff, time-consuming procedures, and complex sample pretreatment, which restricts their use to lab settings.

Because of their high sensitivity, low instrumentation costs, comparatively short analysis times, and the elimination of laborious extraction procedures, electrochemical techniques have become increasingly popular for pharmaceutical, environmental, and biological samples in recent years [13-17]. Screen-printed electrodes (SPE) and interdigital electrodes are two examples of planar substrates used to fabricate sensors. Among them, SPEs are more disposable than other conventional electrodes due to their tiny size, low cost, and light weight. As a result, SPEs are increasingly being used in the creation of electrochemical sensors [18-21].

In electrochemical methods, a problem arises with the working electrodes (e.g. low sensitivity or a short linear range) during sensor device fabrication. The reactivity and selectivity of electrochemical processes may be enhanced and exploited if the physicochemical structure of the interface (between the electrode surface and the solution) is regulated through thoughtful, sensible design. Investigating this area of study, which focuses on the investigation, description, and use of modified electrodes, more especially, the method by which altering an electrode's surface with species possessing particular characteristics can enhance the intended interface, was therefore deemed pertinent [22-26].

Nanomaterials have great promise for use in analytical chemistry as working-electrode modifiers because they exhibit distinctive mechanical, electrical, electronic, optical, magnetic, surface, and biological properties not found in traditional bulk materials [27-30].

Metal-organic frameworks (MOFs) and other porous crystalline structures made of both organic and inorganic components have become popular in recent years. Depending on the intended use, MOFs may be designed as a range of networks with varying chemical and physical properties due to the wide diversity of metal nodes and bridging ligands. MOFs can be used in a variety of applications, including drug delivery, energy storage, gas storage, colorimetric sensors, semiconductors, and more, due to their topological diversity, high specific surface areas, aesthetically pleasing structures, high porosity, and excellent chemical and thermal stability [31-34].

MOFs have emerged as novel electrode materials for electrochemical applications because their porous structure enables precise control of metal-ion electrochemical behaviour. The direct use of MOFs as electrode materials is limited because their mechanical stability is poor and their electrical conductivity is low [35]. The study results show that MOF-based composites exhibit greater stability and electrochemical performance than pure samples across multiple research fields [36]. Researchers have utilized graphene oxide (GO) and other readily available carbon substrates to enhance the conductive performance of MOFs by developing solutions that address existing challenges. The incorporation of MOFs into these materials addresses the widespread issue of graphene nanosheet agglomeration and significantly improves the electrical conductivity of the composite [37-40].

The research team developed a modified screen-printed carbon electrode (SPCE) that enables DOX detection using Zn-Ni MOF nanosheets@GO nanocomposites. The Zn-Ni MOF NSs@GO/SPCE sensor, therefore, showed increased electrocatalytic activity towards DOX. The voltammetric response of DOX showed a linear relationship with concentration over the range 0.004 to 190.0 μM, yielding a detection limit of 0.001 μM. The researchers assessed the practical use of the Zn-Ni MOF NSs@GO/SPCE sensor by testing DOX in real samples, achieving successful results.