We have developed an electrochemical method to quantify the surface density of DNA immobilized on gold. The surface density of DNA, more specifically the number of nucleotide phosphate residues, is calculated from the amount of cationic redox marker measured at the electrode surface. DNA was immobilized on gold by forming mixed monolayers of thiol-derivitized, single-stranded oligonucleotide and 6-mercapto-1-hexanol. The saturated amount of charge-compensating redox marker in the DNA monolayer, determined using chronocoulometry, is directly proportional to the number of phosphate residues and thereby the surface density of DNA. This method permits quantitative determination of both single- and double-stranded DNA at electrodes. Surface densities of single-stranded DNA were precisely varied in the range of (1−10) × 1012 molecules/cm2, as determined by the electrochemical method, using mixed monolayers. We measured the hybridization efficiency of immobilized single-stranded DNA to complementary strands as a...

Electrochemical Quantitation of DNA Immobilized on Gold

We report a strategy for the reagentless transduction of DNA hybridization into a readily detectable electrochemical signal by means of a conformational change analogous to the optical molecular beacon approach. The strategy involves an electroactive, ferrocene-tagged DNA stem-loop structure that self-assembles onto a gold electrode by means of facile gold-thiol chemistry. Hybridization induces a large conformational change in this surface-confined DNA structure, which in turn significantly alters the electron-transfer tunneling distance between the electrode and the redoxable label. The resulting change in electron transfer efficiency is readily measured by cyclic voltammetry at target DNA concentrations as low as 10 pM. In contrast to existing optical approaches, an electrochemical DNA (E-DNA) sensor built on this strategy can detect femtomoles of target DNA without employing cumbersome and expensive optics, light sources, or photodetectors. In contrast to previously reported electrochemical approaches, the E-DNA sensor achieves this impressive sensitivity without the use of exogenous reagents and without sacrificing selectivity or reusability. The E-DNA sensor thus offers the promise of convenient, reusable detection of picomolar DNA.

https://www.pnas.org/content/pnas/100/16/9134.full.pdf

Electrochemical interrogation of conformational changes as a reagentless method for the sequence-specific detection of DNA.

The present paper review the drug-DNA interactions, their types and applications of experimental techniques used to study interactions between DNA and small ligand molecules that are potentially of pharmaceutical interest. DNA has been known to be the cellular target for many cytotoxic anticancer agents for several decades. Understanding how drug molecules interact with DNA has become an active research area at the interface between chemistry, molecular biology and medicine. In this review article, we attempt to bring together topics that cover the breadth of this large area of research. The interaction of drugs with DNA is a significant feature in pharmacology and plays a vital role in the determination of the mechanisms of drug action and designing of more efficient and specifically targeted drugs with lesser side effects. Several instrumental techniques are used to study such interactions. In the present review, we will discuss UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The applications of spectroscopic techniques are reviewed and we have discussed the type of information (qualitative or quantitative) that can be obtained from the use of each technique. Not only have novel techniques been applied to study drug-DNA interactions but such interactions may also be the basis for the development of new assays. The interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases.

Drug-DNA interactions and their study by UV-Visible, fluorescence spectroscopies and cyclic voltametry.

Electrochemiluminescence (ECL) is chemiluminescence triggered by electrochemical techniques. More than 150 ECL assays with remarkably high sensitivity and extremely wide dynamic range are currently available, and accounts for hundreds of millions of dollars in sales per year. The recent development of ECL is particularly rapid. After a brief introduction to ECL, this critical review presents the active and/or emerging areas of ECL research as well as new applications and phenomena of ECL, such as light-emitting electrochemical cell, wireless electrochemical microarray using ECL as photonic reporter, high throughput analysis, aptasensors, immunoassays and DNA analysis, ECL of nanoclusters and carbon nanomaterials, ECL imaging techniques, scanning ECL microscopy, colorimetric ECL sensor, surface plasmon-coupled ECL, electrostatic chemiluminescence, soliton-like ECL waves, ECL investigation of molecular interaction, and single molecule detection. Finally, some perspectives on this rapidly developing field are discussed (322 references).

Applications and trends in electrochemiluminescence.

Publisher Summary The electroactivity of nucleic acids was discovered several years ago. It was shown that at mercury electrodes, adenine and cytosine were reduced in ssDNA while guanine produced an anodic signal due to the oxidation of guanine reduction product. The DNA signals at mercury electrodes are highly sensitive to changes in DNA structure due to DNA denaturation and renaturation, as well as to minor structural changes resulting from DNA premelting and DNA damage. The changes in DNA structure are reflected not only by the DNA faradaic responses but also by non-faradaic signals due to adsorption/desorption of DNA. Several interesting principles have been used in the development of the DNA sensors—such as amplified electrochemical analysis, investigation of charge transport, and tracing of changes in conformation of DNA. The s ensors for DNA hybridization and DNA damage lead the field of the electrochemistry of nucleic acids. The chapter briefly summarizes some properties of the elimination voltammetry with linear scan (EVLS) method. Oscillographic polarography, at controlled alternating current, was used in the electrochemical analysis of nucleic acids.

Electrochemistry of nucleic acids.

Voltammetric methods were used to probe the interaction (electrostatic or intercalative) of metal complexes, ML 3 3+/2+ , with calf thymus DNA. Binding constants (K n+ ) and binding site sizes (s) were determined from voltammetric data. The exact magnitude for the parameters depends on whether the ML 3 3+/2+ /DNA reaction is assumed to be static (S) or mobile (M) within the characteristic time of a voltammetric experiment

/pdf/voltammetric-studies-of-the-interaction-of-metal-chelates-2d59rynbwz.pdf

Voltammetric studies of the interaction of metal chelates with DNA. 2. Tris-chelated complexes of cobalt(III) and iron(II) with 1,10-phenanthroline and 2,2'-bipyridine

Voltammetric studies of the interaction of tris(1,10-phenanthroline)cobalt(III) with DNA

Electrochemical investigations of the interaction of metal chelates with DNA. 3. Electrogenerated chemiluminescent investigation of the interaction of tris(1,10-phenanthroline)ruthenium(II) with DNA.

Michael T. Carter

Papers

Voltammetric studies of the interaction of metal chelates with DNA. 2. Tris-chelated complexes of cobalt(III) and iron(II) with 1,10-phenanthroline and 2,2'-bipyridine

Voltammetric studies of the interaction of tris(1,10-phenanthroline)cobalt(III) with DNA

Electrochemical investigations of the interaction of metal chelates with DNA. 3. Electrogenerated chemiluminescent investigation of the interaction of tris(1,10-phenanthroline)ruthenium(II) with DNA.

Clay modified electrodes: Part VII. The electrochemical behavior of tetrathiafulvalenium-montmorillonite modified electrodes☆