Temat: redoks - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Oligonukleotydy DNA jako warstwy receptorowe sensorów elektrochemicznych
DNA oligonucleotides as receptor layers of electrochemical sensors
Autorzy:: Górski, Ł.
Ziółkowski, R.
Bala, A.
Jarczewska, M.
Malinowska, E.
Powiązania:: https://bibliotekanauki.pl/articles/171556.pdf
Data publikacji:: 2015
Wydawca:: Polskie Towarzystwo Chemiczne
Tematy:: biosensor
metale ciężkie
kwasy nukleinowe
samoorganizujące się monowarstwy
woltamperometria
znaczniki redoks
biosensors
heavy metals
nucleic acids
self-assembled monolayers
voltammetry
redox indicators
Opis:: The need for elaboration of analytical devices of small dimensions and the accessibility of novel nanomaterials caused the increase in the number of publications referring to the development of biosensors. DNA-based biosensors are of special interest and they were primarily used for the determination of a specific sequence which is crucial in the detection of cancer, genetic mutations, pathogens, as well as analysis of modified food. Interestingly, they could be also applied for the detection of other analytes including heavy metal ions, especially in connection with electrochemical techniques. It should be noted that the design of DNA biosensor concerns not only the development of transducer, but also careful preparation of sensing layer and the choice of the method of analytical signal generation. Selectivity is one of the essential parameter of the biosensor that determines its utility, particularly in real samples of complex matrices. In case of DNA sensors dedicated for the detection of complementary sequence, high selectivity is provided by the hybridization process. A pronounced specificity of sensing layer-analyte interaction can be also achieved with the use of functional nucleic acids - aptamers, which change their conformation upon binding an analyte. Herein, DNA-modified electrodes were firstly used for the detection of uranyl ions, as they exhibit high affinity towards phosphate moieties of nuclec acids. It was shown that UO₂ ²⁺ interacts with sensing layer independently from the chosen oligonucleotide sequence. Moreover, the influence of Pb²⁺ was reduced by elimination of adenine, which strongly interacts with lead ions. Another oligonucleotide-based sensor was developed for detection of mercury ions. The results indicate that Hg2+ concentration can be determined only with the use of sequence containing 100% thymine residues. Oligonucleotide-based sensor with receptor layer containing aptamers was elaborated for the detection of Pb²⁺ ions. In the presence of lead cations, an aptamer probe forms a G-quadruplex structure, a proposed biosensor could be characterized with selectivity towards Pb²⁺ The performance of DNA-based sensors for UO₂ ²⁺, Hg²⁺ and Pb²⁺ ions was optimized and addressed the choice of the manner of analytical signal generation, the influence of electrode modification with blocking agent, sensitivity dependence on the oligonucleotide sequence and the possibility of regeneration of sensing layer. Finally, the utility of proposed DNA sensors was tested by analysis in real samples.
Źródło:: Wiadomości Chemiczne; 2015, 69, 5-6; 325-336
0043-5104
2300-0295
Pojawia się w:: Wiadomości Chemiczne
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Dobry amyloid β? Właściwości chemiczne peptydów Aβ4-x wskazują na ich znaczenie biologiczne
Good β-amyloid? Chemical properties of Aβ4-x peptides indicate their biological relevance
Autorzy:: Bal, Wojciech
Powiązania:: https://bibliotekanauki.pl/articles/172163.pdf
Data publikacji:: 2019
Wydawca:: Polskie Towarzystwo Chemiczne
Tematy:: peptydy β-amyloidowe
choroba Alzheimera
ATCUN/NTS
wiązanie Cu(II)
aktywność redoks
amyloid β peptides
Alzheimer’s disease
Cu(II) binding
redox reactivity
Opis:: Alzheimer’s Disease is a neurodegenerative condition, an irreversible progressive dementia caused by death of neurons in brain structures responsible for memory related processes. Despite many years of research and numerous trials, no therapy succeeded that could stop the development of this disease, which affects tens of millions of patients worldwide. The amyloid cascade prevails among a variety of possible mechanisms of its development proposed in the scientific literature. It proposes that death of neurons, preceded by dysfunction of their synaptic activity is caused by the incremental formation of structures (fibrils, oligomers) composed of Aβ peptides. In its copper variant the processes of aggregation and oxidative stress, causing the inflammation and neuronal damage are related to the formation of reactive Cu(II) complexes with Aβ peptides. Aβ peptides are a family of molecules with similar amino acid sequences, differing mainly by the presence of longer or shorter terminal sequences. Their physiological role of is unclear. Aβ_1-42 and Aβ_1-40 have been mostly studied, but most studies have ignored a very abundant N-terminally truncated species Aβ_4-42. We recognized it, and more gene-rally the Aβ_4-x peptide family as potentially strong Cu(II) ligands, due to the presence at their N-termini of the Phe-Arg-His amino acid sequence, comprising the ATCUN/NTS structural motif. This observation was followed by vigorous research performed in our laboratory. We studied the ability of Aβ_4-x peptides to bind Cu(II) ions, their electrochemical properties and redox reactivity, interactions with proteins which bind copper under physiological conditions, their aggregation properties in the Cu(II) presence and susceptibility to proteolysis. Additionally, we investigated their interaction with a molecule of a therapeutic potential. We demonstrated that Aβ4-x peptides can be primary copper bin-ding agents in extracellular spaces in the brain, able to instantaneously intercept copper from Aβ_1-x peptides studied so far. Cu(II) complexes of Aβ_4-x peptides are highly resistant to oxidation and reduction, release copper ions to other molecules slowly and reluctantly, and do not produce reactive oxygen species. In accordance with these properties we proposed a physiological role for the Aβ_4-42 peptide as a molecule cleansing the synaptic cleft from Cu²⁺ ions and thereby assuring the correct neurotransmission. This function can however be disturbed by an inappropriate pharmacological intervention. The results of studies of the effect of cupric ions on the aggregation and membrane interactions of the Aβ_4-40 peptides suggest that copper can inhibit the Aβ_4-x peptides toxicity, thereby providing an additional support for our concept. Studies of hydrolysis of Aβ peptides and properties of its products revealed a possibility for a significant role of short fragments in the brain copper physiology. Our hypothesis awaits verification by biological studies. The issue of metabolism of the studied complexes is a key issue remaining to be solved.
Źródło:: Wiadomości Chemiczne; 2019, 73, 5-6; 351-366
0043-5104
2300-0295
Pojawia się w:: Wiadomości Chemiczne
Dostawca treści:: Biblioteka Nauki

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