Voltammetric and ultraviolet–visible spectroscopic studies on the interaction of etoposide with deoxyribonucleic acid

A comparative application of spectrophotometric and spectrofluorimetric methods to estimate levofloxacin-DNA and ofloxacin-DNA interactions

Ofloxacin (OFL) and its (S)-enantiomer, levofloxacin (LEV), are among members of the fluoroquinolone antibiotic class, renowned for their broad-spectrum efficacy against both gram-negative and gram-positive bacteria. These potent drugs have been widely used in both human and veterinary medicine, working as bactericidal agents by binding to DNA gyrase, an essential enzyme for bacterial DNA replication. Understanding the binding constants of these drugs to DNA is vital for elucidating their interaction mechanisms and enhancing our grasp of gene expression regulation. The interactions of LEV and OFL with calf thymus DNA under a physiological medium (0.02 M tris-HCl buffer, pH 7.4) using UV spectrophotometry and spectrofluorimetry were investigated. The assay results obtained by applying two spectroscopic approaches confirmed the presence of the interaction of LEV and OFL antibiotics with DNA. In the LEV-DNA and OFL-DNA interactions, hyperchromic effect and fluorescence quenching were observed for UV spectrophotometric and spectrofluorometric measurements, respectively. In the spectrophotometric analysis, the binding constants for the LEV-DNA and OFL-DNA complexes at 298 K were determined as (1.24 ± 0.047) x 103 and (1.39 ± 0.040) x 103 M- 1, respectively. In the spectrofluorimetric analysis of the interaction of LEV and OFL with DNA, the thermodynamic properties were examined at three distinct temperatures. Based on the fluorescence signal changes the binding constants at 293, 298, and 310 K were calculated as (8.91 ± 0.161) x 103, (7.62 ± 0.098) x 103, and (6.08 ± 0.041) x 103 M- 1 for LEV-DNA and, (3.14 ± 0.053) x 103, (3.04 ± 0.031) x 103, and (2.78 ± 0.023) x 103 M- 1 for OFL-DNA, respectively. In these assays, the Gibbs free energy (ΔG0), entropy (ΔS0), and enthalpy (ΔH0) were determined using the Van't Hoff equation. The negative ΔG⁰ values indicate that both LEV-DNA and OFL-DNA interactions are spontaneous. Furthermore, the positive ΔS⁰ and negative ΔH⁰ values revealed that electrostatic forces played a significant role in the binding LEV and OFL to DNA.

A new three-dimensional modeling of fluorescence excitation-emission measurements to explore the interaction of hydroxychloroquine and DNA, and to quantify their binding constant

A new three-dimensional chemometric approach was introduced to explore the interaction of hydroxychloroquine (HCQ)-calf thymus deoxyribonucleic acid (DNA) and quantify binding constant using fluorescence excitation and emission measurements. The fluorescence excitation-emission spectra were recorded after gradual titration of HCQ with DNA. Then, the excitation and emission curves and relative concentrations of the drug and drug-DNA complex were quantitatively estimated using a three-dimensional model called Parallel Factor Analysis (PARAFAC) to a cubic fluorescence data array. The interaction of HCQ and DNA was predicted by applying newly modified Stern-Volmer equations to the relationship between the actual DNA concentration, and the HCQ concentration in the relative concentration profile of the PARAFAC model. In the PARAFAC application, the binding constants of the HCQ-DNA complex at 288, 298, and 310 K were found as 6.78 × 103, 5.07 × 103, and 3.74 × 103 L mol-1, respectively. From the temperature studies, the thermodynamic parameters (ΔS0= 3.528 J mol-1 K-1, ΔH0= -20.099 kJ mol-1 and ΔG0=-21.11, -21.12, and -21.19 kJ mol-1 at 288, 298, and 310 K, respectively) were calculated. The drug-DNA interaction is spontaneous due to negative ΔG0 values. The positive ΔS0 and negative ΔH0 values revealed the major role of the electrostatic force on the binding of HCQ to DNA. Assay results obtained from the proposed three-way modeling were compared to those provided by the traditional spectrofluorimetric method.

Electrochemistry as a Powerful Tool for Investigations of Antineoplastic Agents: A Comprehensive Review

Cancer is most frequently treated with antineoplastic agents (ANAs) that are hazardous to patients undergoing chemotherapy and the healthcare workers who handle ANAs in the course of their duties. All aspects related to hazardous oncological drugs illustrate that the monitoring of ANAs is essential to minimize the risks associated with these drugs. Among all analytical techniques used to test ANAs, electrochemistry holds an important position. This review, for the first time, comprehensively describes the progress done in electrochemistry of ANAs by means of a variety of bare or modified (bio)sensors over the last four decades (in the period of 1982-2021). Attention is paid not only to the development of electrochemical sensing protocols of ANAs in various biological, environmental, and pharmaceutical matrices but also to achievements of electrochemical techniques in the examination of the interactions of ANAs with deoxyribonucleic acid (DNA), carcinogenic cells, biomimetic membranes, peptides, and enzymes. Other aspects, including the enantiopurity studies, differentiation between single-stranded and double-stranded DNA without using any label or tag, studies on ANAs degradation, and their pharmacokinetics, by means of electrochemical techniques are also commented. Finally, concluding remarks that underline the existence of a significant niche for the basic electrochemical research that should be filled in the future are presented.

Rapid Detection of the Anti-Tumor Drug Etoposide in Biological Samples by Using a Nanoporous-Gold-Based Electrochemical Sensor

Monitoring etoposide is important due to its wide usage in anti-tumor therapy; however, the commonly used HPLC method is expensive and often requires complicated extraction and detection procedures. Electrochemical analysis has great application prospects because of its rapid response and high specificity, sensitivity, and efficiency with low cost and high convenience. In this study, we constructed a nanoporous gold (NPG)-modified GCE for the detection of etoposide. The electrochemical oxidation of etoposide by NPG caused a sensitive current peak at +0.27 V with good reproductivity in 50 mM of phosphate buffer (pH 7.4). The relationship between etoposide concentration and peak current was linear in the range between 0.1 and 20 μM and between 20 and 150 μM, with a detection sensitivity of 681.8 μA mM-1 cm-2 and 197.2 μA mM-1 cm-2, respectively, and a limit of detection (LOD) reaching 20 nM. The electrode had a good anti-interference ability to several common anions and cations. Spiked recovery tests in serum, urine, and fermentation broth verified the excellent performance of the sensor in terms of sensitivity, reproducibility, and specificity. This may provide a promising tool for the detection of etoposide in biological samples.

Electrochemical DNA sensors for drug determination

In this review, recent achievements in the development of the DNA biosensors developed for the drug determination have been presented with particular emphasis to the main principles of their assembling and signal measurement approaches. The design of the DNA sensors is considered with characterization of auxiliary components and their necessity for the biosensor operation. Carbon nanomaterials, metals and their complexes as well as electropolymerized polymers are briefly described in the assembly of DNA sensors. The performance of the DNA sensors is summarized within 2017-2022 for various drugs and factors influencing the sensitivity and selectivity of the response are discussed. Special attention is paid to the mechanism of the signal generation and possible drawbacks in the analysis of real samples.

Electrochemical Detection of ct-dsDNA on Nanomaterial-modified Carbon Based Electrodes

Background:

Nanomaterials have a significant role in improving the performance of electrochemical sensing systems. Unique physical and chemical properties have extended the application of nanomaterials in the fields of engineering, materials and biomedical science. In the last few years, these materials with unique properties have been preferred in the design of experimental approaches for the analysis of metal ions, proteins, biomarkers and pharmaceutical compounds. This paper reports preparation, characterization of two different nanomaterials and their electrochemical application on doublestranded calf-thymus DNA signals.

Methods:

The multi-walled carbon nanotubes were functionalized with amine groups (MWCNTs-NH2) by employing the dielectric barrier discharge plasma treatment and then applied as MWCNTs- NH2/glassy carbon electrode. Moreover, the synthesized mesoporous silica MCM-41 was chemically amine functionalized and used as MCM-41-NH2/carbon paste electrode. For biosensor preparation, a thin layer of calf thymus double stranded deoxyribonucleic acid (ct-dsDNA) was immobilized over the modified electrodes.

Results:

The influence of dsDNA immobilized substrate was investigated based on the electrochemical signals. While dsDNA/MCM-41-NH2/carbon paste biosensor showed a selective effect for guanine signals, the dsDNA/MWCNTs-NH2/glassy carbon biosensor presented electrocatalytic effect for dsDNA signals. Both dsDNA modified electrodes were employed to explore the interaction between the dsDNA and the anticancer drug etoposide (ETP) in aqueous solution through voltammetric techniques. By increasing the interaction time with ETP, the adenine peak current was quenched in the presence of MWCNTs-NH2 based glassy carbon electrode. Whereas, in the presence of MCM-41-NH2 based CP electrode, selective interaction with guanine occurred and oxidation peak intensity was diminished.

Conclusion:

The selective effect of MCM-41-NH2 can be used when the studied substances give a signal with the same potential of adenine.

Electrochemical sensing of etoposide using carbon quantum dot modified glassy carbon electrode

In this study, carbon quantum dots were used for enhancement of the electrochemical signals of etoposide.