Synergistic NiFeSe₂@Ni-MOF hybrid for sensitive electrochemical determination of valganciclovir in environmental and biological samples.

The extensive use of antiviral drugs has raised growing concerns in environmental and analytical studies due to their persistence in the environment and potential ecological impacts. In this work, a highly sensitive electrochemical sensing platform for valganciclovir (VAL) was constructed using an electrode incorporating NiFeSe₂@Ni-MOF composite. Structural characterization confirmed the successful formation of the nanocomposite and the synergistic integration of both components. FTIR and XRD analyses verified the coexistence of NiFeSe₂ and Ni-MOF with strong interfacial interactions, while XRD revealed a crystallite size of 31.05 nm for the NiFeSe₂@Ni-MOF nanocomposite. BET analysis demonstrated a mesoporous structure with a specific surface area of 15.17 m2 g⁻1 and preserved accessible pore channels favorable for mass transport. FESEM images showed the homogeneous dispersion of NiFeSe₂ nanoparticles over the flower-like Ni-MOF structure, and EDS analysis confirmed the presence and uniform distribution of C, O, Ni, Fe, and Se elements. The analytical performance of the sensor was evaluated using differential pulse voltammetry (DPV) under optimized experimental conditions. A linear relationship was achieved within the concentration range of 0.5-27 μM, with a coefficient of determination of R2 = 0.996. The limits of detection and quantification were found to be 0.0174 μM and 0.058 μM, respectively. The sensor exhibited excellent selectivity in the presence of various interfering substances, along with satisfactory repeatability (RSD = 1.1%) and reproducibility (RSD = 1.3%). In addition, the electrode showed good stability, retaining 95% of its initial response after two weeks. The proposed method was effectively validated in real matrices, including pharmaceutical products, biological fluids (human plasma and urine), and environmental water samples (lake and seawater), yielding satisfactory recoveries between 96.16% and 104.1%. Thus, the proposed sensor offers a dependable, sensitive, and practical method for the detection of VAL in complex sample environments.