Flexible, self-standing 3D NbO/Al MOF embedded hydrogel-derived foam: an efficient electrode for electrochemical sensing of the antituberculosis drug delamanid in biological fluids.

Various analytical techniques are available for the detection of antituberculosis drug delamanid (DLM), whose unregulated dosage can lead to severe health issues. To date, electrochemical sensing of delamanid remains unexplored. In this work, we demonstrate that niobium pentoxide (NbO)/aluminum metal organic framework (Al MOF) nanocomposite is synthesized and incorporated into hydrogel-derived foam (NbO/Al MOF/HFF) for electrochemical sensing of DLM. NbO/Al MOF nanocomposite is synthesized using the hydrothermal method, and NbO/Al MOF/HFF is synthesized by freeze-drying followed by lyophilization. Field emission scanning electron microscopy (FESEM) micrograph reveals successful nanocomposite formation, where NbO nanoparticles are anchored at the edges of rod-like platelet Al MOF. X-ray diffraction (XRD) confirms the crystallinity of NbO/Al MOF incorporated in HFF. Cyclic voltammetry reveals an enhancement in the electrochemical activity of NbO/Al MOF/HFF due to the electrocatalytic activity of Nb/Nb. Using NbO/Al MOF/HFF, electrochemical sensing of DLM is achieved in a linear detection range of 1 nM to 20 µM. Sensitivity of NbO/Al MOF HFF towards DLM is 0.26 nM/µA and exhibits a limit of detection (LOD) of 0.83 nM and limit of quantification (LOQ) of 1.58 nM. The as-fabricated sensor leverages the synergistic effect between redox-active NbO and the porous architecture of Al-MOF to achieve enhanced electrocatalytic performance. Incorporation of NbO contributes to improved electron transfer kinetics and catalytic activity, while Al-MOF serves as active sites. Notably, HFF offers mechanical flexibility and interconnected pathways for electrolyte diffusion, thereby improving sensitivity and reproducibility. The sensor exhibits outstanding selectivity towards delamanid in the presence of interferents. The sensor's excellent sensitivity, selectivity, and reproducibility make it suitable for integration into wearable diagnostics and flexible electrochemical sensors.