A Highly Sensitive Cu–Co MOF/MoSe₂‑Based Electrochemical Sensor for Real-Time Monitoring of Ofloxacin in Environmental Water Samples

Abstract

The development of fast, precise, and cost-effective monitoring devices is necessary to address the growing number of alarms arising from the persistence of antibiotics in aquatic environments. Molybdenum diselenide (MoSe₂) nanosheets and Cu–Co metal organic framework (MOF) were used in the present investigation to design a synergistic electrochemical sensing platform for ofloxacin determination. The Cu–Co MOF is combined with MoSe₂ to make a composite, namely, Cu–Co MOF/MoSe₂. The X-ray diffraction (XRD) analysis shows the planes and crystalline size of the prepared materials. The SEM analysis reveals the flower-like structure morphology of the composite material (MOF/MoSe₂). The electrochemical characterization of the synthesized material has been investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Compared to the single components, the redox reactions of the composite were significantly enhanced by CV and DPV. DPV was performed to determine the limit of detection (LOD) and sensitivity of the prepared materials. The resulting sensitivity of Cu–CO MOF/MoSe₂ is 74.251 μA/μM.cm² and the limit of detection is 1.74 pM (picomolar). The limit of quantification (LOQ) is 5.7973 pM, with a linear range of 0.5–10 μM. Besides its low detection limit and wide linear range, the sensor also demonstrated superior repeatability, reproducibility, and selectivity toward common interferents, including metal ions, glucose, and other antibiotics. Its environmental monitoring application for antibiotic pollutants was demonstrated by its favorable recovery in spiked water samples. The Cu–Co MOF/MoSe₂ hybrid material can be a potential electrochemical sensing material for the rapid and precise detection of ofloxacin in real samples.

1. Introduction

Electrochemical sensing has emerged as one of the most effective analytical approaches for chemical and biological detection. Various sensing techniques have been developed, including biosensing, electrochemical sensing, optical sensing, mass-sensitive (piezoelectric) sensing, and magnetic sensing. Among these, electrochemical sensing has gained significant attention, owing to its high sensitivity, portability, rapid response, and cost-effectiveness. Compared with optical, piezoelectric, and thermal transduction methods, electrochemical sensors utilize simple and low-cost potentiostats and provide near-instantaneous responses, even at trace analyte concentrations. In contrast, optical sensors often require bulky instrumentation and may suffer from turbidity or background fluorescence interference. Electrochemical platforms are particularly attractive for pharmaceutical and environmental monitoring, as they can handle microliter-scale samples and operate reliably in complex matrices, such as biological fluids and wastewater. Moreover, unlike optical or mass-sensitive sensors, which face scaling challenges, electrochemical sensors can be easily miniaturized and integrated into point-of-care devices. Owing to their simplicity, affordability, portability, and ultrasensitivity, electrochemical sensors are well-suited for routine monitoring of antibiotics such as ofloxacin.

Ofloxacin is a broad-spectrum antibiotic that belongs to the fluoroquinolone family of drugs. It exerts its antibacterial activity by inhibiting two essential enzymes, bacterial DNA gyrase and topoisomerase IV, which are responsible for DNA replication, transcription, and repair. Inhibiting these enzymes disrupts DNA supercoiling, ultimately leading to bacterial cell death. For that reason, ofloxacin can be used to treat a wide range of infections because it exhibits high bactericidal activity against both Gram-positive and Gram-negative bacteria. − Apart from the treatment of bacterial infections such as bronchitis, pneumonia, and gonorrhea, ofloxacin is employed for the treatment of skin, bladder, urinary tract, reproductive system, and prostate infections. , Due to the above reasons, ofloxacin in raw materials, formulations, and body fluids has been examined with a range of analytical methods such as spectrofluorometric, spectrophotometry, mass spectrometry, HPLC, capillary electrophoresis, and chemiluminescence. A synthetic antibacterial drug, ofloxacin, is applied to treat Gram-positive and Gram-negative bacteria. To enhance the operation of chemically modified electrodes (CMEs), different conducting or semiconducting materials are used as modifiers. The electromodifiers most commonly applied are ions, carbon nanomaterials (e.g., carbon nanotubes and graphene), , ionic liquid, nanoparticles, phthalocyanine and porphyrin complexes, polymers, and others. Ofloxacin, a potent, broad-spectrum antibiotic prescribed for bacterial infections, is a member of the fluoroquinolone class. Ofloxacin is one of the most frequently utilized fluoroquinolone antibiotics. One of the features that distinguishes ofloxacin from other broad-spectrum antibacterial drugs is the fact that ofloxacin can be administered both orally and intravenously.

As one of the most promising two-dimensional transitional metal dichalcogenide (TMD) materials, molybdenum diselenide has sparked considerable interest over the past few years for electrochemical sensing applications, including the detection of antibiotics such as ofloxacin. MoSe₂ offers an immense number of catalytically active sites, accelerating electron transfer across the electrode interface due to its unique layered structure, high electrical conductivity, and high specific surface area. It is perfect for enhancing the redox response of electroactive analytes like ofloxacin due to such characteristics. Having a moderate band gap of around 1.1–1.5 eV, MoSe₂’s semiconducting character supports efficient movement of charge carriers, and its chemical stability ensures long-term operational reliability. Ofloxacin molecules are adsorbed on the surface of MoSe₂ in the sensing process via hydrogen bonding and π–π stacking interactions, and subsequent electro-oxidation takes place at the active centers of Mo. The interaction of MoSe₂ with conducting or porous materials, such as Cu–Co metal organic frameworks (MOFs), enhances this process immensely by reducing the charge transfer resistance and providing increased catalytic sites. Despite these advantages, pure MoSe₂ has limitations, such as poor selectivity in complex matrices, a tendency to cluster, and relatively moderate inherent sensitivity. Strategies such as surface functionalization, defect engineering, or hybridization with the conducting species can effectively counter these limitations. , For example, the combination of Cu–Co MOF with MoSe₂ enhances electrochemical performance in the composite by merging MOF’s surface area and bimetallic catalysis with better electron transfer abilities of MoSe₂. Enhanced responsiveness to current, reduced R _ct value, and enhanced sensitivity toward ofloxacin detection are the results of such synergistic interactions. Overall, MoSe₂-based electrochemical sensors are a safe and efficient tool for monitoring antibiotics, and they present a rapid, cost-effective, and sensitive solution for biomedical and environmental monitoring.

The electrochemical sensing of antibiotics, such as ofloxacin, using bimetallic Cu–Co MOFs has been highly promising because of their large surface area, tunable porosity, and the synergistic redox activity of the two metal centers. , When Cu²⁺ and Co²⁺ ions are present together, electron transfer and catalytic activity toward the oxidation of ofloxacin molecules are amplified, permitting lower detection limits and better sensitivity compared to monometallic MOFs. The crystalline pore structure of Cu–Co MOFs further facilitates better diffusion and adsorption of ofloxacin at active sites, enhancing the voltammetric response. Cu–Co MOF’s electrocatalytic performance is also improved with their deposition on conductive substrates, such as glassy carbon electrodes or hybrid nanocomposites, leading to enhanced conductivity and stability. Cu–Co MOF-based materials have the potential to produce a reliable and selective electrochemical sensor for detecting environmental antibiotics and monitoring therapeutic drugs due to their specific characteristics.

Bimetallic Cu–Co MOF hybridization with two-dimensional transition metal dichalcogenides, such as MoSe₂, has emerged as a powerful antibiotic sensing method in recent times. MoSe₂ provides outstanding conductivity and a high density of catalytically active edge sites, while Cu–Co MOFs provide porous architecture and a high density of redox-active sites, which facilitate the adsorption of antibiotic molecules. Compared to that of pure MOFs or MoSe₂ alone, the MOF/MoSe₂ hybrid synergistic action enhances electron transfer, enhances current response, and stabilizes the framework against agglomeration, resulting in enhanced sensitivity and reduced detection limits. π–π interactions between the aromatic rings and the MOF framework and coordination of functional groups to Cu–Co centers enhance firm binding and efficient electrochemical reactions in the case of fluoroquinolone antibiotics, such as ofloxacin. Thus, such composites have potential as electrode modifiers in the sensitive, fast, and selective detection of antibiotics in biomedical and environmental samples. The selectivity and sensitivity of electrochemical detection of ofloxacin are constrained by a series of inherent limitations. , Owing to the low intrinsic redox ability of the molecule, electrochemical responses on a bare electrode are weak and ill-defined. High overpotentials are usually required for its oxidation, which reduces sensitivity and increases the chances of interferents from other electroactive species present in real samples. Additionally, ofloxacin often demonstrates poor adsorption onto conventional electrode surfaces, leading to unpredictable and unstable responses. The analytical signal is also suppressed by matrix effects, including electrode fouling caused by proteins, salts, or organic matter in biological and environmental samples. , These challenges indicate that to overcome the limitations of ofloxacin sensing, the electrode surface should be modified with advanced nanostructured materials. Very recently, Chen et al. synthesized the Fe-MOF-NH₂/CNTs-NH₂/MXene composite material, with an LOD of 13.2 nM and a LOQ of 43.33 nM. Taherizadeh et al. synthesized a dual-functional terbium-doped copper oxide with an LOD of 1.2 nM and an LOQ of 4.0 nM. Phung et al. synthesized Cu₂MoS₄ (CMS) with a sensitivity of 0.743 μA μM^–1 cm^–2 and an LOD of 0.058 μM. Vu Thi Huong Mai et al. synthesized the ZnO/ZnCo₂O₄/SPE composite material, with a sensitivity of 1.97 mA mM^–1 cm^–2 and an LOD of 52 nM. Abdelfatah et al. synthesized Zn-MOF@f-MWCNTs/CPE with an LOD of 0.5 × 10^–8 M and an LOQ of 1.7 × 10^–7 Dan Liu et al. synthesized a Trp-Ce–Ti₃C₂ quantum dot material, with an LOD of 0.07 μM. In electrochemical applications such as antibiotic sensing, the combination of a metal–organic framework (MOF) and molybdenum diselenide (MoSe₂) has attracted significant interest due to its large surface area, tunable porosity, and high density of redox-active sites.

In this work, a Cu–Co MOF/MoSe₂ composite electrode is developed for highly sensitive electrochemical detection of ofloxacin. The synergistic integration of the Cu–Co MOF and MoSe₂ results in a high sensitivity of 74.251 μA/μM.cm², an ultralow detection limit of 1.74 pM, an LOQ of 1.74 pM, and excellent analyte performance at neutral pH. These results demonstrate the strong potential of the proposed composite as an efficient, cost-effective, and sensitive electrochemical sensor for monitoring ofloxacin in environmental and pharmaceutical samples. The prepared composite material has high sensitivity and a lower detection limit.

2. Experimental Section

2.1. Materials

The following chemicals were purchased from Merck: copper­(II) nitrate trihydrate [Cu (NO₃)₂·3H₂O], cobalt nitrate hexahydrate [Co­(NO₃)₂·6H₂O ≥ 99% purity], 2-methylimidazole ≥ 98% purity, methanol, ethanol ≥ 99.9% purity, selenium (Se) ≥ 99.9%, hydrazine hydrate (N₂H₄·H₂O) ≥ 99–100%, sodium molybdate dehydrate (Na₂MoO₄·2H₂O) 99%, and distilled water. All of the chemicals were used without any further purification.

2.2. Preparation of Cu–Co MOF

Typically, 4 g of 2-methylimidazole was dissolved in 240 mL of methanol (CH₃OH). The solution was stirred with a magnetic stirrer for 20 min at 50 °C. At the same time, 3.5 g of cobalt nitrate hexahydrate [Co (NO₃)₂·6H₂O] was dissolved in 240 mL of ethanol (CH₃CH₂OH), and 4.5 g of copper­(II) nitrate trihydrate [Cu (NO₃)₂·3H₂O] was dissolved in 240 mL of methanol (CH₃OH) in separate beakers. These solutions were stirred with a magnetic stirrer for 15 min. Afterward, the prepared solutions were added to the 2-methylimidazole solution dropwise. The final solution was stirred for 2 h at 50 °C. Then, it was washed several times with methanol and DI water to remove unwanted particles. It was dried in a vacuum oven at 80 °C overnight. Finally, the obtained material was named Cu–Co MOF. The product yield is 5.08 g. −

2.3. Preparation of the MOF/MoSe₂ Composite

8 mmol of selenium (Se) was dissolved in 5 mL of hydrazine hydrate (N₂H₄·H₂O). 4 mmol of sodium molybdate dehydrate (Na₂MoO₄·2H₂O) was dissolved in 50 mL of distilled water to create a transparent solution (B). Then, solution A was added to solution B drop by drop under continuous stirring for 0.5 h. The solution was transferred into the 100 mL Teflon liner stainless steel autoclave, and then it was sealed and kept in a hot air oven at 200 °C for 24 h. The obtained substance was rinsed with ethanol and distilled water several times. The sample was dried in a vacuum oven at 80 °C for 12 h. The obtained sample is MoSe₂.The yield of the product is 0.667 g. The same procedure was followed for the Cu–Co MOF/MoSe₂ composite, with 0.5 g of the Cu–Co MOF precursor. The yield of the composite material is 0.876 g. −

2.4. Material Characterization

The crystalline properties and phase structure of Cu–Co MOF/MoSe₂ are observed by X-ray diffraction (XRD) (9 kW, RIKAGU, JAPAN) with Cu-Kα, radiation at a wavelength (λ) of 1.54178 Å. Data was collected in the angular range (2θ) from 10 to 70°. The morphology and element features of Cu–Co MOF/MoSe₂ were determined by scanning electron microscopy (SEM) (FESEM, Supra-55, Carl Zeiss, Germany). A Palm Sens 4 electrochemical analyzer was used for all electrochemical experiments, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS).

2.5. Electrode Fabrication for Sensing

A three-electrode setup is used for the electrochemical analysis. In the electrode fabrication, alumina powder was used to polish the GCE. The electrode was then cleaned with distilled water. 1 mL of ethanol containing 4 mg of Cu–Co MOF/MoSe₂ was sonicated for 2 h. The sonicated materials, drop by drop (10 μL), are applied to the GC electrode surface, and then, they are allowed to dry. Sodium phosphate dibasic (Na₂H₂PO₄), sodium phosphate monobasic (NaH₂PO₄), and sodium chloride (NaCl) are the ingredients of phosphate-buffered saline (PBS), an electrolyte solution. The electrolyte solution, which contains 5 mM [Fe (CN)₆]^3–/4– in a three-electrode setup, has a pH of 7.0. Platinum serves as the counter electrode, Ag/AgCl as the reference electrode, and Cu–Co MOF/MoSe₂ as the working electrode. Figure shows the synthesis part of Cu–Co MOF/MoSe₂. For Figure , all of the images were taken from CAMIT LAB, VIT Chennai.

2.

XRD for Cu–Co MOF, MoSe₂, and MOF/MoSe₂.

1.

Schematic diagram of the prepared material Cu–Co/MoSe₂.

3. Results and Discussion

3.1. Structural and Morphology Studies

3.1.1. X-ray Diffraction (XRD) Analysis

The structure, phase, and crystallinity of Cu–Co MOF/MoSe₂, Cu–Co MOF, and MoSe₂, depicted in Figure , were analyzed using XRD data. The Cu–Co MOF exhibits the Co MOF displaying prominent diffraction peaks at 12.8, 22.7, 33.3, 58.2, and 59.9, corresponding to (222), (022), (220), (3̅11), and (035) planes, respectively, CCDC (Cambridge Crystallographic Data Center) Card No. 905134. The Cu MOF displays diffraction peaks at 35.6, 36.8, and 42.4, corresponding to (212), (773), and (1̅33) planes, respectively. The standard data from CCDC Card No. 112954 were compared with the patterns that were obtained. The (002), (004), (100), and (110) crystallographic planes were represented by the peaks at 13.5°, 27.8°, 33.9°, and 54.8° in the hexagonal MoSe₂ XRD pattern, respectively. With its hexagonal configuration, JCPDS Card No. 29-0914 matches these diffraction peaks. The MoSe₂ peaks are very broad, but the only peak at 33.9 is sharp. The MOF/MoSe₂ XRD plot exhibited peaks at 16.2, 28.3, 31.1, 32.9, 36.8, 47.0, and 55.8 corresponding to (422), (044), (220), (212), (773), (105), and (110) planes, respectively. Due to the low degree of crystallinity and surface coverage of the MOF on MoSe₂, along with the relatively low MOF content in the composite, the diffraction intensities corresponding to the (220), (212), and (110) planes are inherently weak. Moreover, the strong diffraction peak of the MoSe₂ phase dominates the XRD pattern.

$$D=\frac{0.9\lambda }{\beta \cos \theta }$$ 1

Using the Debye–Scherrer equation, the average size of the crystalline domains for the intensity peak in the MOF/MoSe₂ composite was determined to be approximately 18.52 nm. Here, β = full width at half-maximum, i.e., FWHM, λ = 1.540 Å (Cu-Kα wavelength), and θ = the diffraction angle of the diffraction peak. Therefore, the acquired X-ray diffraction (XRD) pattern signifies the successful synthesis of MOF/MoSe₂. Table shows the crystalline size of the intensity peak for the proposed materials.

1. Crystalline Size of the Intensity Peak for the Proposed Materials.

materials	FWHM	λ (Cu Kα) (nm)	2θ	K	D (crystalline size) (nm)
Cu–Co MOF	0.4120	0.15406	12.6	0.9	19.75
MoSe2	3.5167	0.15406	33.8	0.9	2.36
MOF/MoSe2	0.4413	0.15406	28.2	0.9	18.52

3.1.2. Scanning Electron Microscopy (SEM)

Figure shows the SEM image of the composite material. According to the SEM image in Figure a, the material consists of densely packed, irregularly shaped, flower-like nanostructures. The aggregated nanoparticles’ surface is rough and porous, as if they are linked together. The presence of some large cluster particles also indicates partial stacking of nanosheets or secondary growth during the synthesis process. The interaction between the MOF and MoSe₂ is inferred by the near which indicates strong interfacial interaction between the MOF and MoSe₂, promoting efficient charge transfer across the heterointerface. The interface distance is very short between the MOF and MoSe₂. A high surface-to-volume ratio is exposed by the finer details, which is pivotal in enhancing catalytic reactions and charge transfer. Good crystallinity and assembly of the hybrid constituents are demonstrated by the relatively smooth interface between the nanoparticles. The SEM image shown in Figure b provides a broader picture of the surface morphology of the MOF/MoSe₂ composite. At this scale, the structure appears to be densely packed, interlinked aggregates of randomly shaped nanoparticles that form large aggregates. The porous, rough surface these aggregates create is beneficial in that it makes a large surface area and enhances interaction with analytes in electrochemical detection. The contrast in the 2 μm image also highlights variations in particle density, illustrating that while the particles assemble into dense clusters, their malleable boundaries might enhance charge transfer and penetration of the electrolyte.

3.

SEM with EDX images of various scale ranges. (a) 200 nm. (b) 2 μM, (c) The elements of Cu–Co MOF/MoSe₂. (d) Elemental mapping.

Figure c shows that the high-resolution SEM (200 nm) is concerned with surface appearance; such mapping discloses the distribution of different elements in the material. Good incorporation of MoSe₂ in Cu–Co MOF is assured by the color-mixed image, in which Mo, Se, Cu, and Co are evenly dispersed without any apparent aggregation or segregation. This uniformity is critical because MO and Se offer high electrical conductivity and rapid electron transport. Several redox-active positions are provided by Cu and Co, enhancing catalytic and electrochemical activity. Mo, Se, Cu, and Co are all homogeneously distributed in the structure, as evidenced by the clear elemental mappings. This shows the composite’s formation and verifies that the synthesis yielded a multielement material with excellent integration. Figure d illustrates that the chemical composition of the composite is identified by the clear peaks in the EDS spectrum for Mo, Se, Cu, Co, C, and O. The occurrence of Mo, Cu, and Co establishes the anticipated mixed-metal MOF/MoSe₂ hybrid structure, with the presence of the intense Se peak as evidence of successful selenium. The relatively weak Mo signal and the strong Se peak observed in the EDS spectrum can be attributed to several intrinsic factors of EDS analysis. Selenium has a higher atomic number and a larger X-ray fluorescence yield than molybdenum, resulting in stronger characteristic X-ray emission under identical measurement conditions. The interaction volume of the electron beam during EDS measurement is dominated by the surface and near-surface regions, since MoSe₂ is composed of Se-terminated layers; thus, selenium atoms are preferentially detected, while Mo atoms are partially shielded. Residual solvent or surface oxidation is likely the source of oxygen.

3.1.3. Brunauer–Emmett–Teller (BET) Analysis

The surface area porosity of the Cu–Co MOF/MoSe₂ composite material was evaluated using the BET nitrogen adsorption–desorption isotherm, as shown in Figure . The relative pressure (P/P ₀) is presented on the X-axis, while the volume of nitrogen adsorbed is shown on the Y-axis. The adsorption branch exhibits a continuous increase with increasing pressure, indicating the strong adsorption capacity of the material and signifying a high surface area of 24.123 m²/g, and the pore volume is 0.168 cm³/g. Furthermore, the presence of a distinct hysteresis loop between the adsorption and desorption branches confirms the mesoporous nature of the material, with a pore diameter of 3.403 nm. This mesoporous structure provides abundant active sites and facilitates efficient mass transport within the framework. Consequently, the high surface area and well-developed porosity significantly enhance the electrochemical performance by promoting effective analyte adsorption and improving electron transfer kinetics, thereby contributing to improved sensing efficiency.

4.

BET analysis of the Cu–Co MOF/MoSe₂ composite.

3.2. Electrochemical Studies

This experiment employed different catalyst loadings, such as 2, 4, 6, 8, and 10 μL, in the working electrode in an electrochemical workstation, as shown in Figure a. It was done using a three-electrode system: a reference electrode, a counter electrode, and a working electrode. Platinum serves as the counter electrode, Ag/AgCl as the reference electrode, and Cu–Co MOF/MoSe₂ as the working electrode. Sodium phosphate dibasic (Na₂H₂PO₄), sodium phosphate monobasic (NaH₂PO₄), and sodium chloride (NaCl) are the ingredients of phosphate-buffered saline (PBS), an electrolyte solution. The electrolyte solution, which contains 5 mM [Fe­(CN)₆]^3–/4– in a three-electrode setup. This CV is done at 50 mV/s. At 2 μL loading, there is a small current response because there is not enough catalyst material, resulting in fewer active sites and lower electron transfer. In the 4 and 6 μL loading, the current increases as more catalyst is present. They have more active surface sites, which improve redox activity. The loading of 8 μL leads to the highest current. This is the optimal loading, where there is a balance between active sites and conductivity. At 10 μL, the current decreases compared to that at 8 μL. Likely due to excessive catalyst film thickness, which hinders electron transfer and causes agglomeration or blocks in conductive pathways. Figure b shows the three-dimensional (3D) bar summary of the results from Figure a. It clearly shows a nonlinear trend, with current increasing steadily from 2 to 8 μL, followed by a sudden drop at 10 μL. The CV curve and 3D plot indicate that the 8 μL catalyst loading yields the maximum current response, while lower or higher loadings are less effective due to underutilization or overloading of the electrode surface. Figure c shows the cyclic voltammetry results of different electrodes and a bar comparison of their current response. The bare electrode shows a low current, so there is limited electrochemical activity. The Cu–Co MOF shows a slightly higher current than the bare electrode, but still relatively low. The MOF still has poor conductivity. MoSe₂ has higher anodic and cathodic peaks than MOF, indicating better conductivity and electron transfer. MOF/MoSe₂ exhibits the highest current response among all. It shows the strong synergistic effect between MOF (high surface area) and MoSe₂ (good conductivity). The composite significantly enhances charge transfer and redox activity, demonstrating superior electrochemical performance compared to individual components. All electrochemical measurements were conducted in 0.1 M PBS with 5 mM [Fe­(CN)₆]^3–/4–, ensuring consistent electrolyte conditions across all electrodes. pH 7 is maintained for the electrolyte solution. Figure d shows a bar diagram that summarizes the peak currents extracted from the CV curves. It clearly shows the increase in the peak current of the composite for both the anode and the cathode. Therefore, the MOF/MoSe₂-modified electrode is the most effective, making it highly suitable for applications like electrochemical sensing, catalysis, and energy storage.

$$\mathrm{Cu}{({\mathrm{NO}}_3)}_2.3{\mathrm{H}}_2\mathrm{O}\to {\mathrm{Cu}}^{2+}+2{{\mathrm{NO}}_3}^{‐}+3{\mathrm{H}}_2\mathrm{O}$$ 2

$$\mathrm{Co}{({\mathrm{NO}}_3)}_2.6{\mathrm{H}}_2\mathrm{O}\to {\mathrm{Co}}^{2+}+2{{\mathrm{NO}}_3}^{‐}+6{\mathrm{H}}_2\mathrm{O}$$ 3

$${\mathrm{Na}}_2{\mathrm{MoO}}_4·2{\mathrm{H}}_2\mathrm{O}+2\mathrm{Se}+{\mathrm{N}}_2{\mathrm{H}}_4·{\mathrm{H}}_2{\mathrm{OMoSe}}_2+2\mathrm{NaOH}+{\mathrm{N}}_2+3{\mathrm{H}}_2\mathrm{O}$$ 4

$${\mathrm{Cu}}^{2+}+{\mathrm{Co}}^{2+}+2{\mathrm{C}}_4{\mathrm{H}}_6{\mathrm{N}}_2\to \mathrm{Cu}-\mathrm{Co}({\mathrm{C}}_4{\mathrm{H}}_5{\mathrm{N}}_2)\mathrm{MOF}+2{\mathrm{H}}^{+}$$ 5

$${\mathrm{MoSe}}_2+\mathrm{Cu}-\mathrm{CoMOF}\to \mathrm{Cu}‐\mathrm{CoMOF}/{\mathrm{MoSe}}_2$$ 6

5.

(a) Different catalyst loadings (2, 4, 6, 8, and 10 μL). (b) 3D plot for the catalyst loading. (c) The difference between the bare electrode, Cu–Co MOF, MoSe₂, and MOF/MoSe₂ with 5 μM antibiotics (ofloxacin) in 50 mV/s. (d). Histogram between bare, unmodified, and modified electrodes and current.

Figure shows the structure of ofloxacin (C₁₈H₂₀FN₃O₄). A fluoroquinolone antibiotic has a characteristic quinolone ring system. A different-pH (pH 3, 5, 7, 9, and 11) study was carried out using MOF/MoSe₂ at a scan rate of 50 mV/s. In the three-electrode system, pH 7 is greater in these five media compared to others, as indicated in Figure a. The MOF/MoSe₂ composite exhibits excellent electron-transport-mediator properties under pH 7 conditions. The effect of various pH levels in Figure b clearly shows that pH 7 is highly suitable for ofloxacin detection.

6.

Structure of ofloxacin.

7.

(a) CV studies in different-pH media (pH 3, 5, 7, 9, and 11). (b) Corresponding pH plot of Cu–Co MOF/MoSe₂.

3.2.1. Cyclic Voltammetry (CV)

Cyclic voltammetry is used to analyze the redox characteristics of the Cu–Co MOF, MoSe₂, and MOF/MoSe₂ in a three-electrode system, as shown in Figure a, at a scan rate of 50 mV/s for working electrodes, a potential range from −0.1 to 1.0 in a 0.1 M PBS solution with 5 mM [Fe­(CN)₆]^3–/4–, and a pH of 7. The oxidation (anodic) and reduction (cathodic) peak currents are 78.76 μA and −76.8 μA for the Cu–Co MOF, 134.93 μA and −94.26 μA for MoSe₂, 172.72 μA and −153.75 μA for MOF/MoSe₂, respectively. The MOF shows poor conductivity with the lowest current. MoSe₂ shows a higher current compared to MOF due to its higher conductivity. MOF/MoSe₂ shows the highest redox peak current because of the synergistic effect. The MOF provides a high surface area, and MoSe₂ enhances the conductivity. The composite material exhibits enhanced electrochemical activity to the greatest extent among all of the investigated electrodes. Figure b shows MOF scan rates between 10 and 100 mV/s.

$${\mathrm{\Delta }E}_{\mathrm{p}}=E_{\mathrm{p}\mathrm{a}}-E_{\mathrm{p}\mathrm{c}}$$ 7

The scan rates increase the peak current from 30 to 110 μA. The redox process is influenced by diffusion and electron transfer kinetics. The high peak separation (ΔE _p = 1.289 V) indicates slow charge transfer. Equation calculates peak separation (ΔE _p), where E _pa refers to the anodic peak potential, and E _pc refers to the cathodic peak potential. Figure c shows different scan rates from 10 to 100 mV/s for MoSe₂. Faster charge transfer due to lower peak separation (ΔE _p = 1.297 V) than MOF. Figure d shows the difference in the scan rate for MOF/MoSe₂. Peak current increases dramatically as the scan rate increases. MOF/MoSe₂ (ΔE _p = 1.329 V) exhibits a large peak current both at the anode and cathode of 200 μA for 100 mV/s. The peak separation is smaller, exhibits good electron transport capacity, and has a large electroactive surface area. The process is quasi-reversible and diffusion-controlled. The composite electrode material generates the highest current with a larger ΔE _p, which means that the effects of conductivity and surface have improved electron transport kinetics. When a process is diffusion-controlled, the peak current (Ip) is proportional to the scan rate’s square root value (V ^1/2). The shape of the CV is broad.

$$I_{\mathrm{p}}=(2.69\times {10}^5)n{}^{3/2}\mathit{AD}{}^{1/2}{\mathit{C\upsilon }}^{1/2}$$ 8

8.

(a) CV analysis of Cu–Co MOF, MoSe₂, and MOF/MoSe₂ at 50 mV/s. (b) CV analysis of Cu–Co MOF. (c) CV analysis of MoSe₂. (d) CV analysis of MOF/MoSe₂ at different scan rates.

In eq , I _p = peak current (A), n = number of electrons transferred, A = electroactive surface area (cm²), D = diffusion coefficient (cm²/s), C = concentration of the electroactive species (mol/cm³), and υ = scan rate (V/s). In the constant area of 0.07 cm², the diffusion coefficients are 1.41 × 10^–5 cm²/s for Cu–Co MOF, 4.12 × 10^–5 cm²/s for MoSe₂, and 6.8 × 10^–5 cm²/s for MOF/MoSe₂. At a constant diffusion coefficient (D) of 7.6 × 10^–6cm²/s, the areas are 0.07 cm² for the bare electrode, 0.095 cm² for Cu–Co MOF, 0.162 cm² for MoSe₂, and 0.208 cm² for MOF/MoSe₂. These areas are larger than the geometric area because modified electrodes with porous/rough surfaces have huge electroactive areas compared to the bare electrode area. It proves that the composite greatly increases the electroactive surface area (ECSA). Figure a–c shows the oxidation and reduction linear fitting calibration plots of Cu–Co MOF, MoSe₂, and MOF/MoSe₂, respectively. Table shows the diffusion coefficient value in a constant area and the area at a constant diffusion coefficient value.

9.

(a) Oxidation and reduction linear calibration plot for MOF. (b) Oxidation and reduction linear calibration plot for MoSe₂. (c) Oxidation and reduction linear calibration plot for MOF/MoSe₂.

2. Diffusion Coefficient and Area of the Synthesized Materials.

materials	A is constant (0.07 cm2)	D is constant (7.6 × 10–6 cm2/s)
Cu–Co MOF	D = 1.41 × 10–5 cm2/s	A = 0.095 cm2
MoSe2	D = 4.12 × 10–5 cm2/s	A = 0.162 cm2
MOF/MoSe2	D = 6.8 × 10–5 cm2/s	A = 0.208 cm2

3.2.2. Differential Pulse Voltammetry (DPV)

The analytic activity of MOF/MoSe₂ is assessed with the DPV method. Differential pulse voltammetry (DPV) was employed for quantitative analysis owing to its high sensitivity. Measurements were conducted in 0.1 M (PBS, pH 7.0) containing 5 mM [Fe­(CN)₆]^3–/^4–, with a pulse time of 0.02 s, a pulse amplitude of 0.05 V, a scan rate of 0.05 mV/s, and a potential window ranging from −0.5 to 1.0 V. The concentration range of the analyte is 0–10 μM. The DPV peak is observed at 0.25 V for Cu–Co MOF. Peak currents from 384 μA to 406 μA are shown in Figure a with increasing analyte concentration from 0 μM to 10 μM. For MoSe₂, the DPV peak is approximately 0.18 V. Figure b shows that the current value increases from 434 μA to 505 μA with increasing concentration. Compared to Cu–Co MOF, it enhances both catalytic activity and electron conduction and exhibits higher sensitivity compared to MOF. For MOF/MoSe₂, there is a slight shift in peak potential toward 0.30 V. Peak current increases rapidly and linearly with analyte concentration. Figure c shows an increase in peak current from 353 μA to 423 μA with increasing concentration from 0 μM to 10 μM. The oxidation peak is very sharp for all modified electrodes.

$$\mathrm{Sensitivity}=\frac{\mathrm{slope}(S)}{\mathrm{area}(A)}$$ 9

$$\mathrm{LOD}=\frac{3.3\sigma }{\mathrm{slope}(S)}$$ 10

$$\mathrm{LOQ}=\frac{10\sigma }{\mathrm{slope}(S)}$$ 11

10.

(a) DPV analysis with antibiotics (ofloxacin) for Cu–Co MOF, (b) MoSe₂, and (c) Cu–Co MOF/MoSe₂.

where S represents the antibiotics calibration curve’s slope, A is the area of the electrode, and σ represents the five blank observations. As calculated with eq , the sensitivity of the Cu–Co MOF is 22.8 μA/μM.cm², and from eq , the limit of detection (LOD) is calculated to be 2.43 pM. From eq , the limit of quantification (LOQ) is calculated to be 8.10 pM, and R ² is 0.9991. As shown in Figure a, the Cu–Co MOF possesses the highest linearity. MoSe₂ possesses good linearity, as shown in Figure b. The sensitivity of MoSe₂ is 70.117 μA/μM.cm², the LOD is 2.45 pM, the LOQ is 8.16 pM, and the R ² is 0.9946. Figure c shows that the Cu–Co MOF/MoSe₂ composite shows excellent linearity compared to MoSe₂. The sensitivity of the composite material Cu–Co MOF/MoSe₂ is 74.251 μA/μM.cm², the LOD is 1.74 pM, the LOQ is 5.80 pM, and the R ² is 0.9972. The strong sensing is reflected by the good linear correlations; R ² is close to 1, which is observed in all materials. Figure a–c shows the linear calibration plot of the Cu–Co MOF, MoSe₂, and Cu–Co MOF/MoSe₂. A comprehensive study is shown in Table .

11.

(a) Linear calibration plot for the Cu–Co MOF. (b) Linear calibration plot for MoSe₂. (c) Linear calibration plot for MOF/MoSe₂.

3. pH, Linear Range, Sensitivity, LOD, LOQ, and R ² of the Prepared Materials Cu–Co MOF, MoSe₂, and Cu–Co MOF/MoSe₂ .

electrode material	aim	pH	linear range (μM)	sensitivity (μA/μM·cm2)	LOD (pM)	LOQ (pM)	R 2
Cu–Co MOF	ofloxacin	7.0	0–10	22.8	2.43	8.1	0.9991
MoSe2	ofloxacin	7.0	0–10	70.1	2.45	8.1	0.9946
Cu–Co MOF/MoSe2	ofloxacin	7.0	0–10	74.2	1.74	5.7	0.9972

3.2.3. Electrochemical Impedance Spectroscopy (EIS)

The Cu–Co MOF exhibits a huge semicircle, extending to approximately 6000 Ω on the real axis and approximately 4000 Ω on the imaginary axis, as shown in Figure . This indicates a very high charge transfer resistance (R _ct), which leads to low conductivity and slow electron transfer. The MoSe₂ semicircle is much smaller compared to the Cu–Co MOF. MoSe₂ has higher electrical conductivity compared to MOF, as indicated by lower R _ct. MOF/MoSe₂’s semicircle is smaller than that of MOF's and slightly smaller than that of MoSe₂'s. This suggests that the incorporation of MOF into MoSe₂ increases charge transfer properties, presumably because the large surface area of MOF and the conductivity of MoSe₂ synergistically function. The composite (MOF/MoSe₂) gives better electron transport and faster ion diffusion. In the fitted equivalent circuit, R ₁ is the solution resistance (R _s) with a value of 176.6 Ω. The interfacial resistance is estimated by R ² (10^–6 Ω), which is an extremely small resistance. Double-layer capacitance in the electrode–electrolyte interface is represented by C1 (0.001 nF). Diffusion-controlled processes (ion diffusion in electrolyte) are accounted for by the Warburg impedance, or W1 (6.737 kΩ). Resistance to the electrolyte, charge transfer, two-layer capacitance, and diffusion are indicated in this circuit to contribute to the system. The MOF/MoSe₂ composite has the lowest charge transfer resistance (R _ct) for MoSe₂, which is intermediate, and for the MOF, it is higher. Thus, the composite electrode is more suitable for applications such as electrocatalysis, sensing, and energy storage, as it provides the fastest electron transfer and the lowest impedance. The charge transfer resistance (R _ct) values are 1300, 550, and 450 Ω for the Cu–Co MOF, MoSe₂, and MOF/MoSe₂, respectively. The semicircle is very large for the MOF; for MoSe₂, it is much smaller; and for MOF/MoSe₂, it is the smallest. This confirms that the composite has the lower charge transfer resistance, best conductivity, and electrochemical performance.

12.

EIS for the Cu–Co MOF, MoSe₂, and MOF/MoSe₂.

3.2.4. Practical Sensing Application

By applying the same electrode to measure five successive measurements of 0.25 μM ofloxacin, the repeatability of the MOF/MoSe₂-modified electrode was estimated (Figure a). The current values are nearly 450 μA across all five trials. This three-electrode system contained ofloxacin at a concentration of 0.25 μM at v = 50 mV/s in a 0.1 M PBS solution with 5 mM [Fe­(CN)₆]^3–/4–. Excellent repeatability and stability in the short term of the electrode were confirmed by nearly equivalent current responses with minimal variation, which is essential for real-world applications requiring reliable and repeated use. Although a uniform font size was initially applied, minor differences between the X-axis and Y-axis font sizes occurred because of figure assembly. Figure b shows that the five electrodes were prepared separately under the same conditions, and the current values ranged from 430 to 460 μA. This three-electrode system was contained with ofloxacin at a concentration of 0.25 μM at v = 50 mV/s in a 0.1 M PBS solution with 5 mM [Fe­(CN)₆]^3–/4–. All electrodes show minimal variation in the error bar. It indicates high reproducibility, reliable fabrication, and consistent sensitivity. The different electrodes show a small variation in electrochemical performance. The sensor fabrication method is more stable and reproducible. The crucial step in validating selectivity and specificity of a sensor is to consider interferents. This three-electrode system contained ofloxacin at a concentration of 0.25 μM at v = 50 mV/s in a 0.1 M PBS solution with 5 mM [Fe­(CN)₆]^3–/4–.

13.

(a) Repeatability of the MOF/MoSe₂ electrode. (b) Reproducibility of the MOF/MoSe₂-modified electrode. (c) Histogram of various interferents vs current. (d) Stability test of the MOF/MoSe₂-modified electrode (all of them contain ofloxacin at a concentration of 0.25 μM at v = 50 mV/s in a 0.1 M PBS solution with 5 mM [Fe­(CN)₆]^3–/4–).

As shown in Figure c, various substances are tested, such as various types of antibiotics and common environmental contaminants. This three-electrode system contained ofloxacin at a concentration of 0.25 μM at v = 50 mV/s in a 0.1 M PBS solution with 5 mM [Fe­(CN)₆]^3–/4–. Since they are common components in biological and environmental samples, glucose, lead, nickel, titanium, bismuth, manganese, sodium chloride, and zinc were investigated as possible interferents in the selectivity study. A stock solution of ofloxacin (1.38 mM) was prepared by dissolving 20 mg ofloxacin in 40 mL of methanol. The concentration of the interfering contaminant is 10-fold that of ofloxacin. The selectivity of the fabricated Cu–Co MOF/MoSe₂ sensor was evaluated by introducing common interfering species such as ascorbic acid, azithromycin, ciprofloxacin, cotrimazole, lead, glucose, tetracycline, nickel, zinc, titanium, bismuth, manganese, and NaCl. The test was performed using DPV techniques under identical conditions. The DPV results showed negligible signal variation for the interferents, while a significant current response was observed for ofloxacin. Even though glucose is capable of participating in electrochemical activity, its signal was much weaker than that of ofloxacin, meaning minimal interference, as shown by the gentle current response for glucose. Due to their high level of redox activity, the lead ions had a somewhat more intense response than glucose, yet were still readily resolved from the ofloxacin peak. Consistent with its electrochemical character, zinc also elicited a detectable current signal, though it did not exceed or interfere with the ofloxacin response. In comparison to ofloxacin, ascorbic acid weakly enhanced the current response in this study, indicating an unfavorable electrochemical interaction with the modified electrodes. The low response shows that interference from ascorbic acid is effectively eliminated by the MOF/MoSe₂ electrode, ensuring precise detection of ofloxacin even in complex sample matrices. Nickel, bismuth, and titanium showed the highest current response. It does not interfere with the ofloxacin current response. Manganese and sodium chloride show lower current compared to the ofloxacin current response. It will not interfere with the analyte’s current response. In order to check the ability of the sensor to distinguish ofloxacin from other drugs, several structurally similar antibiotics were employed during the selectivity study. Azithromycin was weakly electroactive under the conditions used, as evidenced by its quite low current response. Ciprofloxacin, one of the fluoroquinolone antibiotics chemically analogous to ofloxacin, exhibited a larger current than some interferents but still much smaller compared to ofloxacin, proving the sensor’s selective detection. Tetracycline and co-trimoxazole (sulfamethoxazole–trimethoprim) both generated weaker signals, reflecting reduced redox activity at the electrode surface. This clear difference in current response indicates that ofloxacin is the sole antibiotic to which the MOF/MoSe₂ electrode is optimized to respond to, minimizing interference from other commonly used antibiotics. The selectivity toward ofloxacin is limited due to competitive electrochemical responses from coexisting species. Interference was mitigated by optimizing the surface chemistry of the sensing interface to promote preferential interaction with ofloxacin, together with the use of differential pulse voltammetry and optimized operating parameters to enhance signal discrimination. In practical applications, simple sample pretreatment steps, including filtration, dilution, and pH adjustment, can further reduce matrix effects. Structurally similar antibiotics and certain metal ions pose the greatest interference challenge due to overlapping redox behavior and competitive adsorption; however, under optimized conditions, the ofloxacin signal remains distinguishable, enabling reliable screening-level detection in environmental water samples. The four-week stability test of the electrode is given in Figure d. The initial 2 weeks exhibit a relatively high current response that decreases gradually in the third and fourth weeks. This indicates that, although with slight degradation with increasing use, the electrode exhibits good stability and performance with time.

3.2.5. Real-Time Analysis of Ofloxacin Using the Cu–Co MOF/MoSe₂ Electrode

The electrochemical detection of ofloxacin is beset with challenges, even though it is of clinical importance. Because ofloxacin is an amphoteric compound containing both amine and carboxylic acid functional groups, it can display pH-dependent redox behavior and influence the signal stability in electrochemical experiments. Its poor redox reversibility and electroactivity often result in ill-shaped, broad peaks and low current response, complicating quantitative exploration. The Cu–Co MOF/MoSe₂ composite on a GC electrode was used to analyze real-time samples, such as tap water and lake water, using the differential pulse voltammetry technique. The sample water, like tap water, is taken from Vellore Institute of Technology (VIT), Chennai Campus. The lake water is obtained from the nearby area of Keelakottaiyur, Chennai. The sample was used without any dilution or purification. The sample waters were supplemented with antibiotics (ofloxacin) at a concentration ratio of 8:2. The materials were analyzed using DPV techniques in a 0.1 M PBS solution containing 5 mM [Fe­(CN)­6]^3–/4–. The spiked concentrations of the real-time samples are 10, 20, 30, 40, and 50 μL. Then, the peak current was measured after the addition of each real-time sample to determine the recovery percentage (%) of ofloxacin, as shown in Table . The recovery percentage range is 95–99% for the real-time sample at various concentrations. The average RSD value is 0.21%. In summary, it can be assured from the data that the MOF/MoSe₂ sensor is beneficial for detecting ofloxacin concentrations in real spiked samples. The low RSD results indicated that the sensor operated reliably, with good percent recoveries and minimal variability in the environment. The MOF/MoSe₂ composite on GCE was used to analyze real-time samples. The recovery and RSD analysis of real-time samples is shown in Table . Table shows the comparison of antibiotics in previous articles.

4. Real-Time monitoring of Ofloxacin in Various Environmental Water Samples.

real-time samples	added (μL)	found (μL)	recovery (%)	RSD (%)
tap water	10	9.64	96.44	0.48
	20	19.37	97.15	0.32
	30	28.84	97.64	0.21
	40	38.96	98.10	0.13
	50	49.71	99.67	0.23
lake water	10	9.85	98.57	0.24
	20	19.63	98.18	0.08
	30	29.56	98.56	0.19
	40	38.29	95.74	0.10
	50	47.75	95.51	0.12

5. Comparative Study of Antibiotics.

materials	pH	linear range	aim	sensitivity	LOD	LOQ	R 2	advantage	references
peony-like CuO: Tb3+	6	0.01 and 800 μM	ofloxacin (OFL)		1.9 nM	6.3 nM	0.999	multianalyte fluoroquinolone detection
peony-like CuO: Tb3+	6	0.01 and 800 μM	pefloxacin		2.3 nM	7.6 nM	0.999	multianalyte fluoroquinolone detection
peony-like CuO: Tb3+	6	0.01 and 800 μM	gatifloxacin		1.2 nM	4.0 nM	0.999	multianalyte fluoroquinolone detection
C-SPE/GNC/ISM (CX6)	2.9	1 × 10–6 to 1 × 102 M	ofloxacin (OFL)		6 × 10–7 M		0.999	broad concentration range
GO-IL/CPE	6	7.0 × 10–9 to 7.0 × 10–7 mol L–1	ofloxacin (OFL)	7.7 × 106 μAL mol–1	2.8 × 10–10 mol L–1			moderate sensitivity
Ca2CuO3 NS	4	0.09–1.0 μM	ofloxacin (OFL)		0.027 μM	0.09 μM	0.990	low detection limit
Ca2CuO3 NS	4	0.05–0.8 μM	ciprofloxacin		0.012 μM	0.04 μM	0.988	low detection limit
ZnO/GR/GCE	5.0	1–100 mM	ofloxacin (OFL)	1399.86 μA mM–1 cm2	0.33 μM	1.1 μM	0.995	high sensitivity
M-CuCo2O4/3DrGO	6.0	0.15–174.52 μM	thiamethoxam (TMX)		0.6 nM	2.01 nM		low detection limit by 3D architecture
Cu-MOF-SPE	5	0.0001–100 μmol L–1	tetracycline		1.007 μmol L–1	3.356 μmol L–1	0.99	high absorption capacity
Cu2MoS4 (CMS)		0.25–100 and 100–1000 μM	ofloxacin (OFL)	0.743 μA μM–1 cm –2	0.058 μM	0.193 μM		dual linear range
MIP-MWCNTs-OH/COF/GCE	4.0	1.969 × 10–11 to 9.619 × 10–9 M	ofloxacin (OFL)		4.989 × 10–12 M	1.663 × 10–11 M	0.991	good selectivity due to molecular imprinting
Th-Cu-MOF/MWCNTs	5.0	9 nM to 2.5 μM	pefloxacin (PFL)		2.6 nM		0.992	improved conductivity due to MWCNT incorporation
Fe-MOF NH2/CNTs-NH2/MXene composite	6.0	0.1–100 μM	ofloxacin (OFL)		13.2 nM	43.33 nM	0.998	higher electron transfer efficiency
Cu–Co MOF/MoSe2	7.0	0–10 μM	ofloxacin (OFL)	74.251 μA/μM·cm2	1.74 pM	5.797 pM	0.997	ultralow LOD, high sensitivity, and neutral pH	this work

4. Conclusion

Cu–Co MOF and MoSe₂ composites form an efficient electrochemical sensing platform for the sensitive and targeted detection of ofloxacin. The large surface area and multiple active sites of the bimetallic MOF, combined with the excellent conductivity and catalytic properties of MoSe₂, significantly enhance the charge transfer kinetics and electrochemical responsiveness. Compared to virgin samples, the Cu–Co/MOFMoSe₂ composite determines improved repeatability, lower detection limits, and higher sensitivity. These results indicate that it has potential as an electrode material for fluoroquinolone antibiotic monitoring, which can be applied in pharmaceutical analysis and environmental monitoring. The proposed material offers a sensitivity of 74.2518 μA/μM cm^–2, a limit of detection (LOD) of 1.73 pM, a limit of quantification (LOQ) of 5.797 pM, and a correlation coefficient R ² of 0.9972, with a broad detection range of 0–10 μM. We have practically applied the Cu–Co MOF/MoSe₂ composite-modified GCE to detect ofloxacin in real-time samples of tap water and lake water with a good recovery percentage. The Cu–Co MOF/MoSe₂ hybrid enhances sensitivity and selectivity and lowers the detection limit. Moreover, even in complex sample matrices, the porous framework ensures consistent responses and minimizes electrode fouling. The Cu–Co MOF/MoSe₂ composite is a promising sensing material for precise and efficient ofloxacin detection due to these combined features.

All data are included in the manuscript itself.

S.S.: original draft, writing, data analysis, and synthesis. E.M.: review and editing.

The authors declare no competing financial interest.