Natural phenolic compounds are abundant in the vegetable kingdom, occurring mainly as secondary metabolites in a wide variety of chemical structures. Around 10,000 different plant phenolic ...derivatives have been isolated and identified. This review provides an exhaustive overview concerning the electron transfer reactions in natural polyphenols, from the point of view of their in vitro antioxidant and/or pro‐oxidant mode of action, as well as their identification in highly complex matrixes, for example, fruits, vegetables, wine, food supplements, relevant for food quality control, nutrition, and health research. The accurate assessment of polyphenols’ redox behavior is essential, and the application of the electrochemical methods in routine quality control of natural products and foods, where the polyphenols antioxidant activity needs to be quantified in vitro, is of the utmost importance. The phenol moiety oxidation pathways and the effect of substituents and experimental conditions on their electrochemical behavior will be reviewed. The fundamental principles concerning the redox behavior of natural polyphenols, specifically flavonoids and other benzopyran derivatives, phenolic acids and ester derivatives, quinones, lignins, tannins, lignans, essential oils, stilbenes, curcuminoids, and chalcones, will be described. The final sections will focus on the electroanalysis of phenolic antioxidants in natural products and the electroanalytical evaluation of in vitro total antioxidant capacity.
Applications of a DNA-electrochemical biosensor Diculescu, Victor Constantin; Chiorcea-Paquim, Ana-Maria; Oliveira-Brett, Ana Maria
TrAC, Trends in analytical chemistry (Regular ed.),
20/May , Letnik:
79
Journal Article
Recenzirano
•Design of DNA-electrochemical biosensors that use DNA direct electrochemistry.•AFM and voltammetric characterization of new immobilisation procedures described.•Self-assembled nanostructures of DNA, ...G-quadruplex, and i-motif presented.•Application for label-free detection of DNA interactions and damage.•Interaction with proteins, drugs, metals, pollutants, radicals, and radiation, revised.
As carrier of genetic information, DNA is one of the most important intracellular targets that undergo modification and damage upon interaction with endogenous and exogenous factors. DNA is an excellent biomaterial for the construction of new devices, in nanotechnology and biosensor technology, for evaluation of DNA interaction with a broad range of chemical compounds and biomolecules, essential from a biological and a medical point of view.
This review discusses recent advances on the design and applications of DNA-electrochemical biosensors that use DNA direct electrochemistry as a detection platform. AFM and voltammetric characterization of new bottom up immobilisation procedures of self-assembled nanostructures based on DNA single- and double-stranded, G-quadruplex, and i-motif configurations are presented, relevant for the development of new DNA-electrochemical biosensor devices. The applications of DNA-electrochemical biosensors, for the label-free detection of interactions with proteins, pharmaceutical compounds, metal ions and metal complexes, pollutants, free radicals, and electromagnetic radiation, were revisited.
Deoxyribonucleic acid (DNA) electrochemical biosensors are devices that incorporate immobilized DNA as a molecular recognition element on the electrode surface, and enable probing in situ the ...oxidative DNA damage. A wide range of DNA electrochemical biosensor analytical and biotechnological applications in pharmacology are foreseen, due to their ability to determine in situ and in real-time the DNA interaction mechanisms with pharmaceutical drugs, as well as with their degradation products, redox reaction products, and metabolites, and due to their capacity to achieve quantitative electroanalytical evaluation of the drugs, with high sensitivity, short time of analysis, and low cost. This review presents the design and applications of label-free DNA electrochemical biosensors that use DNA direct electrochemical oxidation to detect oxidative DNA damage. The DNA electrochemical biosensor development, from the viewpoint of electrochemical and atomic force microscopy (AFM) characterization, and the bottom-up immobilization of DNA nanostructures at the electrode surface, are described. Applications of DNA electrochemical biosensors that enable the label-free detection of DNA interactions with pharmaceutical compounds, such as acridine derivatives, alkaloids, alkylating agents, alkylphosphocholines, antibiotics, antimetabolites, kinase inhibitors, immunomodulatory agents, metal complexes, nucleoside analogs, and phenolic compounds, which can be used in drug analysis and drug discovery, and may lead to future screening systems, are reviewed.
► Electrochemical behaviour of phenol, catechol, hydroquinone, resorcinol, dopamine. ► Electrochemical behaviour of
para-substituted phenolic compounds, 4-ethylphenol, tyrosine, and tyramine. ► ...Electrochemical mechanistic behaviour of
para-substituted phenols.
The electrochemical behaviour of phenol, catechol, hydroquinone, resorcinol, dopamine, and
para-substituted phenolic compounds, 4-ethylphenol, tyrosine, and tyramine, was studied over a wide pH range using a glassy carbon electrode. The oxidation of phenol is pH dependent and irreversible, occurring in one step, and followed by hydrolyse in
ortho- and
para-positions, leading to two oxidation products, catechol and hydroquinone. The oxidation of phenol oxidation products,
ortho-phenol and
para-phenol, is reversible and pH dependent. The oxidation potential of
para-substituted phenols varies slightly due to their substituent group in position C4, and occurs in one oxidation step corresponding to the oxidation of phenol. The oxidation products of this group of
para-substituted phenols are reversibly oxidised and adsorb on the electrode surface.
Alkylating agents were among the first anticancer drugs to be discovered and continue to be the most commonly used in chemotherapy. They are electrophiles that react with the ring nitrogen and ...extracyclic oxygen atoms of DNA bases, forming covalent adducts that further lead to cross-linking of DNA strands, abnormal base pairing or DNA strand breaks. The investigation and quantitative analysis of alkylating agents in biological samples are essential for monitoring the therapy progression and efficiency, understanding their pharmacokinetics and develop new more effective and specific chemotherapeutical drugs. Among biotechnological methods, electrochemical techniques are particularly important in pharmaceutical medicine, owing to their rapid detection, great sensitivity, robustness, exceptional detection limits, ability to be used with small analyte volumes in turbid biofluids, and easy adaptability to miniaturization and point-of-care (POC) testing. This article provides first an exhaustive review concerning the electrochemical methods of characterization and quantification of different classes of chemotherapeutic alkylating agents (triazenes and hydrazines, nitrosoureas, nitrogen mustards, oxazaphosphorines, alkyl alkane sulfonates and ethylene imines) in standard samples, pharmaceutical formulations and biological matrixes. The second part of the article focuses on the recent electrochemical methodologies and DNA-electrochemical biosensors developed to study the interaction of alkylating agents with DNA. These studies are relevant for obtaining real-time details about the alkylating agents’ mechanism of action and for assessing the oxidative DNA damage they cause, important for the development of improved antineoplastic drugs.
Display omitted
•Alkylating agents were among the first anticancer drugs used in chemotherapy.•They react with DNA bases, forming covalent adducts.•Electrochemical methods to study chemotherapeutic alkylating agents.•DNA-electrochemical biosensors developed to study DNA-alkylating agents’ interaction.
Oxidative DNA damage plays an important role in the pathogenesis of various diseases. Among oxidative DNA lesions, 8-oxoguanine (8-oxoG) and its corresponding nucleotide 8-oxo-2′-deoxyguanosine ...(8-oxodG), the guanine and deoxyguanosine oxidation products, have gained much attention, being considered biomarkers for oxidative DNA damage. Both 8-oxoG and 8-oxodG are used to predict overall body oxidative stress levels, to estimate the risk, to detect, and to make prognosis related to treatment of cancer, degenerative, and other age-related diseases. The need for rapid, easy, and low-cost detection and quantification of 8-oxoG and 8-oxodG biomarkers of oxidative DNA damage in complex samples, urine, blood, and tissue, caused an increasing interest on electrochemical sensors based on modified electrodes, due to their high sensitivity and selectivity, low-cost, and easy miniaturization and automation. This review aims to provide a comprehensive and exhaustive overview of the fundamental principles concerning the electrochemical determination of the biomarkers 8-oxoG and 8-oxodG using nanostructured materials (NsM), such as carbon nanotubes, carbon nanofibers, graphene-related materials, gold nanomaterials, metal nanoparticles, polymers, nanocomposites, dendrimers, antibodies and aptamers, and modified electrochemical sensors.
Graphical abstract
The time-dependent structural modifications and oxidation behavior of specifically chosen five short amyloid beta (Aβ) peptides, Aβ1–16, Aβ1–28, Aβ10–20, Aβ12–28, and Aβ17–42, fragments of the ...complete human Aβ1–40 peptide, were investigated by atomic force microscopy (AFM) and voltammetry. The objective was to determine the influence of different Aβ domains (VHHQ that contains electroactive histidine H residues, KLVFF that is the peptide hydrophobic aggregation core, and IIGLMVGGVV that is the C-terminus hydrophobic region), and of Aβ peptide hydrophobicity, in the fibrilization mechanism. The short Aβ peptides absence of aggregation or the time-dependent aggregation mechanisms, at room temperature, in free chloride media, within the time window from 0 to 48 h, were established by AFM via changes in their adsorption morphology, and by differential pulse voltammetry, via modifications of the amino acid residues oxidation peak currents. The first oxidation peak was of tyrosine Y residue and the second peak was of histidine H and methionine M residues oxidation. A correlation between the presence of an intact highly hydrophobic KLVFF aggregation core and the time-dependent changes on the Aβ peptides aggregation was found. The hydrophobic C-terminal domain IIGLMVGGVV, present in the Aβ1–40 peptide, also contributed to accelerate the formation of Aβ1–40 peptide aggregates and fibrils.
Guanine-rich DNA sequences are able to form G-quadruplexes, being involved in important biological processes and representing smart self-assembling nanomaterials that are increasingly used in DNA ...nanotechnology and biosensor technology. G-quadruplex electrochemical biosensors have received particular attention, since the electrochemical response is particularly sensitive to the DNA structural changes from single-stranded, double-stranded, or hairpin into a G-quadruplex configuration. Furthermore, the development of an increased number of G-quadruplex aptamers that combine the G-quadruplex stiffness and self-assembling versatility with the aptamer high specificity of binding to a variety of molecular targets allowed the construction of biosensors with increased selectivity and sensitivity. This review discusses the recent advances on the electrochemical characterization, design, and applications of G-quadruplex electrochemical biosensors in the evaluation of metal ions, G-quadruplex ligands, and other small organic molecules, proteins, and cells. The electrochemical and atomic force microscopy characterization of G-quadruplexes is presented. The incubation time and cations concentration dependence in controlling the G-quadruplex folding, stability, and nanostructures formation at carbon electrodes are discussed. Different G-quadruplex electrochemical biosensors design strategies, based on the DNA folding into a G-quadruplex, the use of G-quadruplex aptamers, or the use of hemin/G-quadruplex DNAzymes, are revisited.
The electrochemical behaviour of indole and a group of indole‐containing compounds with a substituent at the C3 position, indol‐3‐acetamide (IAM), tryptamine, gramine, indole acetic acid (IAA), ...indole propionic acid (IPA), indole butyric acid (IBA) and tryptophan, was investigated at a glassy carbon electrode, in order to determine their oxidation pathways. Indole undergoes one irreversible pH dependent oxidation, whereas the oxidation process of indole derivatives was more complex, a two step, the oxidation at C2 position on the pyrrole ring followed by the hydroxylation at the C7 position of the benzene moiety of indoles, irreversible pH dependent oxidation.
Alzheimer's disease (AD) is a widespread form of dementia that is estimated to affect 44.4 million people worldwide. AD pathology is closely related to the accumulation of amyloid beta (Aβ) peptides ...in fibrils and plagues, the small oligomeric intermediate species formed during the Aβ peptides aggregation presenting the highest neurotoxicity. This review discusses the recent advances on the Aβ peptides electrochemical characterization. The Aβ peptides oxidation at a glassy carbon electrode occurs in one or two steps, depending on the amino acid sequence, length and content. The first electron transfer reaction corresponds to the tyrosine Tyr10 amino acid residue oxidation, and the second to all three histidine (His6, His13 and His14) and one methionine (Met35) amino acid residues. The Aβ peptides aggregation and amyloid fibril formation are electrochemically detected via the electroactive amino acids oxidation peak currents decrease that occurs in a time dependent manner. The Aβ peptides redox behaviour is correlated with changes in the adsorption morphology from initially random coiled structures, corresponding to the Aβ peptide monomers in random coil or in α-helix conformations, to aggregates, protofibrils and two types of fibrils, corresponding to the Aβ peptides in a β-sheet configuration, observed by atomic force microscopy. Electrochemical studies of Aβ peptides aggregation, mediated by the interaction with metal ions, particularly zinc, copper and iron, and different methodologies concerning the detection of Aβ peptide biomarkers of AD in biological fluids, using electrochemical biosensors, are also discussed.
PDF
