Ru(II) Oxygen Sensors for Co(III) Complexes and Amphotericin B Antifungal Activity Detection by Phosphorescence Optical Respirometry.

The measurement of oxygen consumption is an important element in the understanding of an organism's metabolic state. Oxygen is also a phosphorescence quencher, which allows the evaluation of phosphorescence emitted by oxygen sensors. Two Ru(II)-based oxygen-sensitive sensors were used to study the effect of chemical compounds [( 1 ) = [CoCl 2 (dap) 2 ]Cl, and ( 2 ) = [CoCl 2 (en) 2 ]Cl (AmB = amphotericin B) against reference and clinical strains of Candida albicans . The tris -[(4,7-diphenyl-1,10-phenanthroline)ruthenium(II)] chloride ([Ru(DPP) 3 ]Cl 2 ) (Box) adsorbed onto the Davisil TM silica gel was embedded in the silicone rubber Lactite NuvaSil ® 5091 and the coating on the bottom of 96-well plates. The water-soluble oxygen sensor (BsOx = tris -[(4,7-diphenyl-1,10-phenanthrolinedisulphonic acid disodium)ruthenium(II)] chloride 'x' hydrate = {Ru[DPP(SO 3 Na) 2 ] 3 }Cl 2 = water molecules were omitted in the BsOx formula) was synthesized and characterized by RP-UHPLC, LCMS, MALDI, elemental analysis, ATR, UV-Vis, 1 H NMR, and TG/IR techniques. The microbiological studies were performed in the environment of RPMI broth and blood serum. Both Ru(II)-based sensors turned out to be useful in the study of the activity of Co(III) complexes and the commercial antifungal drug amphotericin B. In addition, a new activity of the oxygen sensor, the soluble Ru(II) complex BsOx, was demonstrated, which is a mixture with amphotericin B that caused a significant increase in its antifungal activity. Thus, it is also possible to demonstrate the synergistic effect of compounds active against the microorganisms under study.