Electrochemical studies of interactions of pyronine B with RNA and determination of RNA

Interaction ofpyronine B (PB) with yeast RNA (yRNA) has been studied by electrochemical method on a hanging mercury drop electrode (HMDE) in 0.2 mol L -1 Britton-Robinson (B-R) buffer solution. Under selected conditions, voltammetric peak at -0.90 V (vs SCE) corresponding to reduction of PB was formed. After addition of yRNA, the height of the reduction peak of PB apparently decreased and its potential exhibited a positive shift; no new redox peaks were observed. Some electrochemical properties of PB were quantitatively determined in the absence and in the presence of yRNA. It has been found that the values of E 0 , k s , an, etc. changed in the presence of yRNA, which indicated the formation of electroactive PB-RNA complex. yRNA was electroinactive in the selected potential range. Consequently, redox activity of PB in PB-RNA biocomplex was lowered and the corresponding peak height was decreased, as well as the peak potential was shifted. Conditions of the binding reaction and electrochemical detection of PB have been optimised. Under optimum conditions a decrease of peak current was linearly proportional to the concentration of yRNA in the range 1.0-35.0 μg mL -1 . The corresponding regression equation is: ΔIp(nA) = 24.12C (μg mL -1 ) + 25.27 (n = 14, r = 0.993), detection limit is 0.73 μg mL -1 (3σ). The proposed method has been applied to the determination of yRNA in synthetic samples with satisfactory results.