Designing an electrochemical biosensor for the investigation of albumin-DNA interactions

An electrochemical analysis of the interaction of double-stranded DNA (dsDNA) with bovine serum albumin (BSA) as model protein was carried out. A decrease in the electrochemical oxidation peak current of DNA nucleobases was evaluated in the DNA-BSA complex at a BSA concentrations above 0.1 μM, which indicated compaction of the DNA structure with a formation of partial clew and shielding of guanine, adenine, and thymine available for electrode reactions. At a BSA concentration below 0.1 μM in DNA-BSA complex, an increase in the intensity of heterocyclic bases electro oxidation was observed, indicating partial unwinding of the DNA double strand. Using a calorimetric assay, the enthalpy of ΔH = + 2620.4 J/g was registered for DNA-BSA complex with low BSA concentration (below 0.1 μM), and ΔH = + 82.7 J/g for high BSA concertation (above 0.1 μM). The binding constants of the DNA-BSA complex based on adenine and thymine electrochemical signals were K b = 4.52 × 10 6 M −1 and K b = 3.99 × 10 6 M −1 , respectively. The spectral binding constant of the DNA-BSA complex was determined as an integral parameter and corresponded to K b = 3.98 × 10 6 M −1 , which in good agreement with electrochemical K b values. ● The DNA-BSA complexes were studied electrochemically. ● Two binding mechanisms were observed depending on the BSA concentration. ● The binding constants of the DNA-BSA complexes were determined. ● Thermodynamic profiles of the DNA-BSA complexes were obtained. ● The positive enthalpy ΔH 0 indicates an endothermic process with energy heat adsorption.