Electrochemical Behavior of Thalidomide at a Glassy Carbon Electrode

First voltammetric analysis of two possible anticancer drug candidates using an unmodified glassy carbon electrode

Dimethyl 2-[2-(1-phenyl-4,5-dihydro-1H-imidazol-2-yl)hydrazinylidene]butanedioate (DIHB) and 8-(3-chlorophenyl)-2,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3,4-dione (HDIT) are promising candidates for anticancer agents, the first analytical procedures of which are presented in this paper. The commercially available unmodified glassy carbon electrode (GCE) was used as a sensor for the individual and simultaneous differential pulse voltammetric (DPV) determination of these possible anticancer drugs. The findings concerning the electrochemical behaviour indicated that DIHB and HDIT display at GCE, as a sensor, the oxidation peaks at 1.18 and 0.98 V, respectively (vs. Ag/AgCl, 3.0 mol L-1 KCl) in the 0.125 mol L-1 acetate buffer of pH = 4.5, which were employed for their quantification. Various experimental parameters were carefully investigated, to achieve high sensitivity in voltammetric measurements. Finally, under the optimised conditions (t of 60 s, ΔEA of 75 mV, ν of 225 mV s-1, and tm of 2 ms), the proposed DPV procedure with the GCE demonstrated broad linear sensing ranges (1-200 nmol L-1-DIHB and 5-200 nmol L-1-HDIT), boasting the detection limits of 0.18 nmol L-1 for DIHB and 1.1 nmol L-1 for HDIT. Moreover, the developed procedure was distinguished by good selectivity, repeatability of DIHB and HDIT signals and sensor reproducibility. The practical application of this method was demonstrated by analysing the urine reference material without any prior treatment. The results showed that this environmentally friendly approach, with a modification-free sensor, is suitable for the sensitive, selective and rapid quantification of DIHB and HDIT.

Triazole-acridine conjugates: redox mechanisms and in situ electrochemical evaluation of interaction with double-stranded DNA

Redox mechanisms and in situ electrochemical interaction with double-stranded DNA were investigated using a DNA-electrochemical biosensor for two disubstituted triazole-linked acridine compounds (GL15 and GL7), previously reporting as quadruplex DNA-binding molecules. The redox properties of GL15 and GL7 involve a complex, pH-dependent, adsorption-controlled irreversible process and were investigated using cyclic, differential pulse, and square wave voltammetry at a glassy carbon electrode. The interaction between duplex DNA and GL15 or GL7 was investigated in incubated solutions using dsDNA-, poly[G]-, and poly[A]-electrochemical biosensors. It was demonstrated that the interaction is time-dependent, both GL15 and GL7 interacting with dsDNA, causing condensation of dsDNA morphological structure but not oxidative damage.