Electrochemical studies of the interaction of rifampicin and nanosome/rifampicin with dsDNA

The interactions of dsDNA with rifampicin (RF) or with rifampicin after encapsulation in phospholipid micelles (nanosome/rifampicin) (NRF) were studied electrochemically. Screen-printed electrodes (SPEs) modified by stable dispersions of multi-wolled carbon nanotubes (MWCNTs) in aqueous solution of poly(1,2-butadiene)-block-poly(2-(dimethylamino)ethyl methacrylate) (PB290-b-PDMAEMA(240)) diblock copolymer were used for quantitative electrochemical investigation of direct electrochemical oxidation of guanine at E = 0.591 V (vs. Ag/AgCl) and adenine at E = 0.874 V (vs. Ag/AgCl) of dsDNA and its change in the presence of RF or NRF. Due to RF or NRF interaction with dsDNA, the differential pulse voltammetry (DPV) peak currents of guanine and adenine decreased and the peak potentials shifted to more positive values with increasing drug concentration (RF or NRF). Binding constants (K-b) of complexes RF-dsDNA and NRF-dsDNA were calculated based on adenine and guanine oxidation signals. The K-b values for RF-dsDNA were 1.48 x 10(4) M-1/8.56 x 10(4) M-1, while for NRF-dsDNA were 2.51 x 10(4) M-1/1.78 x 10(3) M-1 (based on adenine or guanine oxidation signals, respectively). The values of K-b revealed intercalation mode of interaction with dsDNA for RF and mixed type of interaction (intercalation and electrostatic mode) for NRF. The estimated values of Delta G (Gibbs free energy) of the complex formation confirmed that drug-dsDNA interactions are spontaneous and favourable reactions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The electrochemical interactions of dsDNA with rifampicin (RF) and rifampicin encapsulated in phospholipid micelles (nanosome/rifampicin) (NRF) were studied. The study showed that the interaction of RF or NRF with dsDNA affected the oxidation signals of guanine and adenine. The binding constants and Gibbs free energy values indicated different modes of interaction between the drugs and dsDNA.