Probing Qualitative Change in Intermolecular Forces from Hydrogen Bonding to Electrostatic Interaction on the Surface of Self-Assembled Monolayer

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We carried out thorough cyclic voltammetric (CV) studies to evaluate the intermolecular interactions between the electrochemical label and the liquor compounds. In the cyclic voltammograms, both the anodic and cathodic peak potential of FcCH 2 OH were positively shifted, resulting from the formation of hydrogen bonding between FcCH 2 OH and C 2 H 5 OH. Only the anodic peak potential of FcCH 2 OH was positively shifted, resulting from the formation of ion-pair between the oxidized form (Fc + CH 2 OH) and the negatively charged carboxylate (RCOO − ). Combining cyclic voltammetry and gas chromatography, the result shows an evident correlation between peak potential and the content of the negatively charged ions present in the liquor (e.g., 1 mM sodium acetate with the potential shift of +40 ± 5 mV; 1 mM sodium citrate with the potential shift of +38 ± 4 mV). Further, a fast approach (total scanning time: 56 s), which is complementary to the conventional chromatographic and mass spectrographic characterizations, has been developed for differentiating aging times (1, 2, 3, 4, 5 and 10 years) of typical Chinese liquors.

Section: Resultsmentioning

confidence: 73%

Modulated Interactions between the Electrochemical Label and Liquor Compounds: Differentiating between Aging Times of Typical Chinese Liquors

Zhao

Gao

et al. 2020

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“…After drying with nitrogen, the non-covalent ME-CD-DOPA SAMs was obtained. 28,29 Another spotless gold electrode was immersed in an ethanol solution of 0.01 M mercapto polyethylene glycol dopamine 48 h for the z E-mail: Ximinghuang_SYU@163.com covalent assembly. After washing with ethanol and drying with nitrogen, the covalent SH-PEG-DOPA SAMs was obtained.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Dopamine Release on Self-assembled Monolayers by Scanning Electrochemical Microscopy

Wang¹,

Tang²,

Liu³

et al. 2022

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Dopamine, a neurotransmitter, controls many psychological and behavioral activities of the mammalian central nervous system. Over secretion of dopamine can make the body overexcited and lead to mental disorders, whereas less secretion can lead to the development of Parkinson's symptoms. Therefore, achieving controlled release of dopamine plays a vital role in life sciences. In this work, two kinds of self-assembled monolayers were prepared by non-covalent and covalent assembly, respectively, to reach the function of dopamine controllable release. After characterization of the two self-assembled monolayers, the release function was well monitored and analyzed by scanning electrochemical microscopy. The result showed that ion pair effect, as well as acids and alkali, would stimulate a steady-state release of dopamine on the non-covalent monolayers. The combined effect of alkali and positive potential would stimulate a steady-state release of dopamine on the covalent monolayers. This work successfully reaches the controllable release of dopamine in vitro, and offers some reference value for this function in vivo.

“…It should be noted that electrochemical detection during DNA melting may be affected by interactions between the redox label and the thiol SAM used to passivate the surface. 66 Mechanistic insights.-As highlighted in the previous sections, electrochemical melting of DNA SAMs has been demonstrated using both constant and scanning potential techniques to discriminate sequences based on mismatches, and other mutations, for both short and long sequences. These studies confirm the possibility of using electrochemical melting for diagnostic applications.…”

Section: Electrochemical Melting Of Dna Monolayersmentioning

confidence: 99%

Review—Electrical Manipulation of DNA Self-Assembled Monolayers: Electrochemical Melting of Surface-Bound DNA

West

2020

DNA provides a powerful framework for the development of biosensors, DNA chips, bioelectronics, and other established and emerging technologies. Many of these applications involve DNA self-assembled monolayers (SAM) on conducting surfaces where the high molecular density, the two-dimensional nature of the interface, and the limited mobility of the strands significantly impact the behavior of the DNA. The unique steric and electrostatic conditions present in the SAM dominate hybridization, melting, and motion of the tethered oligonucleotides. At neutral pH the charged sugar-phosphate backbone makes the DNA sensitive to the electric fields present in the electrical double-layer. Electrode charge provides a means of modifying the reactivity of DNA monolayers; facilitating enhanced rates of hybridization, controlling orientation, and inducing melting (i.e. denaturation). Understanding the effects of electric fields on DNA monolayers is a prerequisite to the optimization of next generation DNA biosensors and other applications that take advantage of DNA’s selective self-assembly. This mini-review will give an overview of the ways in which electrochemical control can be used to manipulate DNA SAMs. In particular, the process of electric field-assisted melting of DNA, i.e. electrochemical melting, will be reviewed. Electrochemical melting has the potential for providing biophysical insights and for the development of new diagnostic applications.