Monitoring isoniazid level in human fluids in the presence of theophylline using gold@platinum core@shell nanoparticles modified glassy carbon electrode

We report the electrochemical determination of anti-tuberculosis drug, isoniazid (INH) using gold-platinum core-shell nanoparticles (Au@PtNPs) modified glassy carbon electrode (GCE). The Au@PtNPs modified GCE was fabricated by electroless deposition of AuNPs by reducing HAuCl₄ in the presence of NH₂OH followed by the electroless deposition of PtNPs in the presence of H₂PtCl₆ and NH₂OH. The initially deposited AuNPs act as the nucleation centre and catalyzed the deposition of PtNPs. Scanning electron microscopy (SEM) studies suggest that the electroless deposition of Pt on Au was isotropic and uniform. Then, the GC/Au@PtNPs electrode was exploited for the determination of INH in the presence of theophylline (TP). It was found that GC/Au@PtNPs electrode not only enhanced the oxidation currents of INH and TP but also shifted their potentials toward less positive potential in contrast to bare GCE. The present modified electrode was successfully used to determine these drugs simultaneously in a mixture. Selective determination of INH in the presence of 100-fold higher concentration of TP was also achieved at GC/Au@PtNPs electrode. The amperometric current response was increased linearly while increasing the concentration of INH from 50 × 10^-9 to 100 × 10^-6 M with a correlation coefficient of 0.998 and the limit of detection was found to be 26 × 10^-9 M (S/N = 3). Finally, the practical application of the present modified electrode was demonstrated by simultaneously determining the concentrations of INH and TP in human blood serum and urine samples.