Electrochemical investigation on the interaction of diclofenac with DNA and its application to the construction of a graphene-based biosensor

Interaction of nickel ferrite nanoparticles with nucleic acids

In this article, we introduced an electrochemical biosensor employing graphite electrodes (GE) decorated with Nickel ferrite (NiFe₂O₄) nanoparticles for nucleic acid detection. NiFe₂O₄ nanoparticles in a narrow size distribution were synthesized with co-precipitation technique. Their chemical and crystallographic properties were characterized with FTIR and X-ray spectroscopies. Nanoparticle size distribution and hydrodynamic diameter were determined with particle size analyzer. Elemental content and purity of nanoparticles were analyzed with EDX analysis. Our analyses showed a diameter of ~10 nm for NiFe₂O₄ nanoparticles. Electrochemical properties of NiFe₂O₄ nanoparticles were examined with different analysis methods. Conductivity properties of NiFe₂O₄ nanoparticles were investigated with Cyclic Voltammetry (CV), which confirmed that nanoparticles on GE surface have a high surface area and conductivity. More importantly, in this article, the interactions between NiFe₂O₄ nanoparticles and double stranded DNA (dsDNA), single stranded DNA (ssDNA), and RNA were for the first time examined using Differential Pulse Voltammetry (DPV), CV, and Electrochemical Impedance Spectroscopy (EIS). Oxidation peak currents of NiFe₂O₄ nanoparticles and guanine bases of dsDNA, ssDNA, and RNA showed that NiFe₂O₄ nanoparticles effectively interacts with nucleic acids via an electrostatic mode.

Spectroscopic and electrochemical approaches for the analysis of interaction between textile dye 231 and salmon sperm DNA

DNA is one of the most critical targets for many artificial agents listed as carcinogens. Most of them irreversibly bind to the DNA and induce genome mutation; therefore, it is vital to study the nature of binding of these molecules to anticipate their toxicity. The interaction between the textile dye reactive red 231 and salmon sperm double-stranded DNA (ss-dsDNA) was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and ultraviolet-visible spectroscopy (UV–vis spectroscopy). Changes in the anodic current signals of the dye were observed in the presence and absence of ss-dsDNA at a glassy carbon electrode (GCE) using CV. The diffusion coefficient (D) was found to be 2.2 × 10–7 and 9.5 × 10–8 cm2 s−1 from the CV data for the free dye and dye-DNA complex, respectively. Electrochemical and UV–vis spectroscopy indicated 1:1 complex formation of the dye with DNA. The binding constant (kb) between the dye and DNA was calculated to be 5.4 × 105 M–1 and 4.9 × 105 M–1 at pH 4.0 using CV and UV–vis spectroscopy, respectively. Overall, these results suggest that the dye binds to DNA through the combined effect of intercalation and electrostatic interactions. DNA damage was also detected through changes in the voltammetric behaviour of the dye.

Differences in electrochemical response of prospective anticancer drugs IPBD and Cl-IPBD, doxorubicin and Vitamin C at plasmid modified glassy carbon

For the comparison of the DNA interactions with drugs, two newly synthesized prospective anticancer drugs, 6-(1H-imidazo[4,5-b]phenasine-2-yl)benzene-1,3-diol (IPBD) and, its -Cl derivative (Cl-IPBD) have been compared with doxorubicin, a drug widely used in medicine, and with Vitamin C. These compounds were accumulated at a supercoiled scpUC19 plasmid layer formed on a glassy carbon electrode (GCE). Stability of the drug-plasmid/GCE layer was achieved by initial plasmid accumulation using prolonged potential cycling for ca. 200 min. from highly diluted scpUC19 solutions (8 pg/mL), followed by accumulation of the drugs from 1 µM - 50 µM. Electrochemical properties in terms of the redox potentials of the compounds and capacitative/resistive characteristics of the layers have been tested using, in sequence, four voltammetric methods: Square Wave (SWV), Differential Pulse (DPV) and Alternating Current (ACV) with phase detection 0° and 90°. Importantly, with progressive drug accumulation in the plasmid, for Cl-IPBD, but not for IPBD, an increase in peak (I) at -0.42 V vs. SCE was observed, while biological tests revealed a higher cytotoxic activity for Cl-IPBD vs. IPBD. Moreover, an additional redox signal of Cl-IPBD was observed with the compound reductive accumulation at the plasmid layer in the presence of Vitamin C.

Off-line and real-time monitoring of acetaminophen photodegradation by an electrochemical sensor

The photochemistry of N-acetyl-para-aminophenol (acetaminophen, APAP) is here investigated by using differential pulse voltammetry (DPV) analysis to monitor APAP photodegradation upon steady-state irradiation. The purpose of this work is to assess the applicability of DPV to monitor the photochemical behaviour of xenobiotics, along with the development of an electrochemical set-up for the real-time monitoring of APAP photodegradation. We here investigated the APAP photoreactivity towards the main photogenerated reactive transients species occurring in sunlit surface waters (hydroxyl radical HO, carbonate radical CO₃^-, excited triplet state of anthraquinone-2-sulfonate used as proxy of the chromophoric DOM, and singlet oxygen ¹O₂), and determined relevant kinetic parameters. A standard procedure based on UV detection coupled with liquid chromatography (HPLC-UV) was used under identical experimental conditions to compare and verify the DPV-based results. The latter were in agreement with HPLC data, with the exception of the triplet-sensitized processes. In the other cases, DPV could be used as an alternative to the well-tested but more costly and time-consuming HPLC-UV technique. We have also assessed the reaction rate constant between APAP and HO by real-time DPV, which allowed for the monitoring of APAP photodegradation inside the irradiation chamber. Unfortunately, real-time DPV measurements are likely to be affected by temperature variations of the irradiated samples. Overall, DPV appeared as a fast, cheap and reasonably reliable technique when used for the off-line monitoring of APAP photodegradation. When a suitable real-time procedure is developed, it could become a very straightforward method to study the photochemical behaviour of electroactive xenobiotics.

Pharmacogenomic study using bio- and nanobioelectrochemistry: Drug-DNA interaction

Small molecules that bind genomic DNA have proven that they can be effective anticancer, antibiotic and antiviral therapeutic agents that affect the well-being of millions of people worldwide. Drug-DNA interaction affects DNA replication and division; causes strand breaks, and mutations. Therefore, the investigation of drug-DNA interaction is needed to understand the mechanism of drug action as well as in designing DNA-targeted drugs. On the other hand, the interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases. For this purpose, electrochemical methods/biosensors can be used toward detection of drug-DNA interactions. The present paper reviews the drug-DNA interactions, their types and applications of electrochemical techniques used to study interactions between DNA and drugs or small ligand molecules that are potentially of pharmaceutical interest. The results are used to determine drug binding sites and sequence preference, as well as conformational changes due to drug-DNA interactions. Also, the intention of this review is to give an overview of the present state of the drug-DNA interaction cognition. The applications of electrochemical techniques for investigation of drug-DNA interaction were reviewed and we have discussed the type of qualitative or quantitative information that can be obtained from the use of each technique.