Mixing nitrogenous ligands in osmium(VI)ligand-polysaccharide complexes. Voltammetric sensing

Abstract

• Electroinactive dextran was modified with complexes of Os(VI) and nitrogenous ligands. • Os(VI)ligand modified dextran is electroactive and yields several redox peaks. • Nitrogenous ligand type significantly influences interfacial properties of modified dextrans. • Ligand combination can improve dextran analysis comparing to one-ligand modification. Simple chemical modification of carbohydrates with complexes of sixvalent osmium and nitrogenous ligands (Os(VI)L) changes electro inactive carbohydrates to electroactive species. In this work we show that the type of the nitrogenous ligand (L) significantly influences adsorption of Os(VI)L-modified dextrans at a charged surface. Modification by mixture containing two ligands can improve electrochemical analysis in comparison to simple modification only with one ligand. For instance, modification with complexes of Os(VI) and mixture of N,N,Ń,Ń-tetramethylethylenediamine (temed) with 2,2́-bipyridine (bipy) allows to (i) determine the concentration of Os(VI)L modified dextran in one order higher range as in case of dextran modified only with Os(VI)temed and (ii) discriminate between various polysaccharides differing in building units and structures.