Voltammetric and adsorption study of 4-nitrophenyl-triazole-labeled 2′-deoxycytidine and 7-deazaadenosine nucleosides at boron-doped diamond electrode

Electrochemical properties of 4-nitrophenyl triazole labeled 2′-deoxycytidine (dCTRNO2) and 7-deazaadenosine (dATRNO2) were studied using alumina-polished boron doped diamond (BDD) electrode in acetate buffer pH 5.0. Cyclic voltammetry revealed peak-shaped signals for reduction of the nitro group at the potentials of ca − 0.6 V (vs. AgƖAgClƖ3 mol L− 1 KCl reference electrode) and for the hydroxylamine/nitroso pair exhibiting quasireversible electron transfer at potentials comparable with redox processes of other nitro aromatic compounds at BDD electrodes. All electrochemical processes are directed by adsorption. Moreover, ex situ adsorption of dATRNO2 and transfer to supporting electrolyte enables its quantitation using square wave voltammetry in small (several microliter) sample volumes after optimization of parameters for the hydroxylamine/nitroso redox couple. Competitive adsorption/desorption at the BDD surface was further studied by cyclic voltammetry with dATRNO2 in the presence of electrochemically inactive phenyl triazole 7-deazaadenosine conjugate (dATR), revealing mutual displacement of both compounds at BDD surface. Further, the redox processes of simpler aromatic nitro compounds (4-nitrophenyl acetylene and 2-nitronaphthalene) are strongly affected when the BDD surface is covered by dATR.