Cu-Fe Prussian blue analog nanocube with intrinsic oxidase mimetic behaviour for the non-invasive colorimetric detection of Isoniazid in human urine

Isoniazid (INH) is a crucial antibiotic widely applicable in the chemotherapy of Tuberculosis. Any discrepancy of INH in the blood may be life-threatening and causes neurotoxicity and other health issues. In this work, we present a colorimetric technique for the easy quantification of the INH in human urine. We have synthesized Cu-Fe Prussian blue analogue nanocube (CuFe-PBA-NC) using a simple precipitation method. The synthesized nanocube has been successfully characterized by Fourier transfer infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The synthesized CuFe-PBA-NC act as an excellent oxidase mimic, having a very high affinity for TMB (3,3′,5,5′-tetramethylbenzidine) furnishing a blue color compound with a characteristic absorbance peak at λmax = 652 nm. Further, we have exploited the oxidase property of CuFe-PBA-NC for the colorimetric detection of the INH in human urine. The developed sensor shows very high sensitivity in the range of 1 to 100 μM with a detection limit of 0.44 μM. Furthermore, a portable kit was developed for the onsite detection of the INH concentrations in the test samples. The method is easy and cost-effective with sensitive detection of INH.