ELECTROCHEMICAL BEHAVIORS OF MATRINE AT L-CYSTEINE-MODIFIED ELECTRODES

2008 ◽  
Vol 15 (05) ◽  
pp. 537-543 ◽  
Author(s):  
YUQING MIAO ◽  
JIANRONG CHEN ◽  
XIAOHUA WU
Keyword(s):  
Ph Value ◽  
Modified Electrodes ◽  
Underlying Mechanism ◽  
Distribution Coefficients ◽  
Spectroscopic Techniques ◽  
Current Response ◽  
Electrochemical Behaviors ◽  
Electrochemical Approach ◽  
Wide Range ◽  
Assembled Monolayers

Matrine is an important natural occurring component in sophora roots. It has a wide range of pharmacological actions. In this work, electrochemical investigation of matrine and its interaction with L-cysteine (L-Cys) is reported. Via the electrochemical approach, we have proved that the distribution coefficients of protonated and deprotonated matrine affect its electrochemical response on Au or L-Cys modified Au electrodes. The study by ultraviolet spectroscopy also finds that the molecular interaction between matrine and L-Cys changes with the distribution coefficients of protonated and deprotonated matrine at different pH value. Compared with the response of matrine on the bare gold electrode, the L-Cys/Au self-assembled monolayers modified electrodes exhibit obviously higher current response toward matrine oxidation. The oxidation current of matrine at L-Cys assembled electrode has a good linear relation in the range of 0.2–5 mM, with the correlation coefficient of 0.989 by cyclic voltammagrams. Electrochemical combined with spectroscopic techniques would provide relatively easy way to better understand the underlying mechanism of matrine/L-Cys interaction and will be helpful for the development of electroanalytical techniques for the determination of matrine.

Preventing biofilms by chitosan-based nanoantimicrobials (NAMs)

2020 ◽  
Author(s):  
Ekaterina A. Kukushkina ◽  
Maria Chiara Sportelli ◽  
Nicoletta Ditaranto ◽  
Rosaria Anna Picca ◽  
Nicola Cioffi
Keyword(s):  
Antimicrobial Activity ◽  
Food Packaging ◽  
Metal Oxide Nanoparticles ◽  
Biological Action ◽  
Spectroscopic Techniques ◽  
Biofilm Growth ◽  
Electron Microscopies ◽  
Research And Innovation ◽  
Electrochemical Approach ◽  
Wide Range

<p>Chitosan (CS), a natural non-toxic polysaccharide, shows intrinsic antimicrobial activity against a wide range of pathogens. CS and CS-based biomaterials can be effective additives in food and medicine-related industries to inhibit growth of pathogens. The application of inorganic nanophases, such as metal and metal oxide nanoparticles, has received attention due to their broad and pronounced antimicrobial activity. Upon combination with CS, which can act as stabilizer, with active inorganic nanophases, robust synergistic nanoantimicrobial (NAM) systems can be produced. These hybrid NAMs offer an alternative strategy to fight antimicrobial resistance and overcome limitations of conventional antibiotics. Bioactive ZnO, Cu and Ag nanophases produced by green electrochemical approach [Nanomaterials, 10(3) (2020), 473] and laser ablation in solution [(Coll. Surf. A, 559 (2018), 148-158), (Food packaging shelf, 22 (2019), 1000422)] can be combined with antimicrobial CS to develop synergistic antimicrobial nanohybrids with amplified biological action. CS-based NAMs were preliminary characterized by electron microscopies and spectroscopic techniques. Hybrid NAMs may find application in the control and inhibition of biofilm growth.</p> <p>Acknowledgements<br />Financial support is acknowledged from European Union’s 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 813439</p>

Study of parameters affecting microcontact printing of thiols on gold-coated substrate

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040040
Author(s):  
Swapna A. Jaywant ◽  
Khalid Mahmood Arif
Keyword(s):  
Molecular Weight ◽  
Soft Lithography ◽  
Ph Value ◽  
Microcontact Printing ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Wide Range ◽  
Assembled Monolayers ◽  
Time Required ◽  
Compound Concentration

Microcontact printing ([Formula: see text]CP) is a type of soft-lithography technique, which is widely used for patterning self-assembled monolayers (SAMs). It is a convenient method to form SAMs of bio/chemical ink onto different surfaces such as polymers, palladium, silver and gold. A wide range of applications of this technology includes micromachining, patterning proteins, cells or DNA in biosensors. However, the application primarily depends on the type of the ink used. Here, we present an experimental study that provides information about the parameters that affect the [Formula: see text]CP process. Two different thiol inks (dithiothreitol (DTT) and glutathione (GSH)) have been used for obtaining SAMs on gold-coated substrates. Our findings suggest that transferring the alkanethiols over the gold surface is extremely dependent upon the molecular weight of thiol compound, concentration of the thiol solution and pH value of the buffer used. Furthermore, higher the molecular weight, concentration and pH value of the ink, lower is the time required for the process of [Formula: see text]CP.

Chalcones: As potent α-amylase enzyme inhibitors; synthesis, in vitro, and in silico studies

2020 ◽  
Vol 16 ◽  
Author(s):  
Mahboob Ali ◽  
Momin Khan ◽  
Khair Zaman ◽  
Abdul Wadood ◽  
Maryam Iqbal ◽  
...  
Keyword(s):  
In Silico ◽  
Enzyme Inhibitors ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Type Ii Diabetes Mellitus ◽  
Spectroscopic Techniques ◽  
Chalcone Derivatives ◽  
In Silico Studies ◽  
Wide Range

: Background: The inhibition of α-amylase enzyme is one of the best therapeutic approach for the management of type II diabetes mellitus. Chalcone possesses a wide range of biological activities. Objective: In the current study chalcone derivatives (1-17) were synthesized and evaluated their inhibitory potential against α-amylase enzyme. Method: For that purpose, a library of substituted (E)-1-(naphthalene-2-yl)-3-phenylprop-2-en-1-ones was synthesized by ClaisenSchmidt condensation reaction of 2-acetonaphthanone and substituted aryl benzaldehyde in the presence of base and characterized via different spectroscopic techniques such as EI-MS, HREI-MS, 1H-, and 13C-NMR. Results: Sixteen synthetic chalcones were evaluated for in vitro porcine pancreatic α-amylase inhibition. All the chalcones demonstrated good inhibitory activities in the range of IC50 = 1.25 ± 1.05 to 2.40 ± 0.09 μM as compared to the standard commercial drug acarbose (IC50 = 1.34 ± 0.3 μM). Conclusion: Chalcone derivatives (1-17) were synthesized, characterized, and evaluated for their α-amylase inhibition. SAR revealed that electron donating groups in the phenyl ring have more influence on enzyme inhibition. However, to insight the participation of different substituents in the chalcones on the binding interactions with the α-amylase enzyme, in silico (computer simulation) molecular modeling analyses were carried out.

scholarly journals Electrochemical Detection of Endosulfan Using an AONP-PANI-SWCNT Modified Glassy Carbon Electrode

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 723
Author(s):  
Kgotla K. Masibi ◽  
Omolola E. Fayemi ◽  
Abolanle S. Adekunle ◽  
Amal M. Al-Mohaimeed ◽  
Asmaa M. Fahim ◽  
...  
Keyword(s):  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Modified Electrodes ◽  
Antimony Oxide ◽  
Current Response ◽  
Carbon Electrode ◽  
Trace Detection ◽  
Limit Of Quantification ◽  
Walled Carbon Nanotubes

This report narrates the successful application of a fabricated novel sensor for the trace detection of endosulfan (EDS). The sensor was made by modifying a glassy-carbon electrode (GCE) with polyaniline (PANI), chemically synthesized antimony oxide nanoparticles (AONPs), acid-functionalized, single-walled carbon nanotubes (fSWCNTs), and finally, the AONP-PANI-SWCNT nanocomposite. The electrochemical properties of the modified electrodes regarding endosulfan detection were investigated via cyclic voltammetry (CV) and square-wave voltammetry. The current response of the electrodes to EDS followed the trend GCE-AONP-PANI-SWCNT (−510 µA) > GCE-PANI (−59 µA) > GCE-AONPs (−11.4 µA) > GCE (−5.52 µA) > GCE-fSWCNTs (−0.168 µA). The obtained results indicated that the current response obtained at the AONP-PANI-SWCNT/GCE was higher with relatively low overpotential compared to those from the other electrodes investigated. This demonstrated the superiority of the AONP-PANI-SWCNT-modified GCE. The AONP-PANI-SWCNT/GCE demonstrated good electrocatalytic activities for the electrochemical reduction of EDS. The results obtained in this study are comparable with those in other reports. The sensitivity, limit of detection (LoD), and limit of quantification (LoQ) of AONP-PANI-SWCNT/GCE towards EDS was estimated to be 0.0623 µA/µM, 6.8 µM, and 20.6 µM, respectively. Selectivity, as well as the practical application of the fabricated sensor, were explored, and the results indicated that the EDS-reduction current was reduced by only 2.0% when interfering species were present, whilst average recoveries of EDS in real samples were above 97%.

scholarly journals Electrochemical Detection of Phenanthrene Using Nickel Oxide Doped PANI Nanofiber Based Modified Electrodes

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Omolola E. Fayemi ◽  
Abolanle S. Adekunle ◽  
Eno E. Ebenso
Keyword(s):  
Nickel Oxide ◽  
Square Wave Voltammetry ◽  
Modified Electrodes ◽  
Oxidation Potential ◽  
Current Response ◽  
Modified Glassy Carbon Electrode ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Doped Polyaniline ◽  
Uv Visible

A nickel oxide doped polyaniline nanofibers (PANI-NiO) based electrochemical sensor was constructed for detection of phenanthrene. Successful synthesis of PANI-NiO nanocomposite was confirmed with techniques such as SEM, XRD, EDX, FTIR, and UV-visible spectroscopy. The electrocatalytic oxidation of phenanthrene on PANI-NiO on modified glassy carbon electrode (GCE-PANI-NiO) was studied using cyclic voltammetry, square wave voltammetry, and impedance spectroscopy and discussed. Results showed that detection of phenanthrene was enhanced by the nanostructure of PANI-NiO film. The square wave voltammetry analysis shows a very low detection limit of 0.732 pM for phenanthrene with the linear range of 7.6 pM–1.4 × 10−11 M. The Tafel value of 227 mVdec−1suggests adsorption of phenanthrene oxidation intermediates on the GCE-PANI-NiO electrode. The GCE-PANI-NiO modified electrodes gave better performance towards phenanthrene in terms of current response, oxidation potential, current recovery, stability, and resistance to electrode fouling effects.

scholarly journals Cryptand-Functionalized Highly Oriented Pyrolytic Graphite Electrodes

2021 ◽  
Vol 13 (8) ◽  
pp. 4158
Author(s):  
Marcos A. Bento ◽  
Sara Realista ◽  
Ana S. Viana ◽  
Ana M. Ferraria ◽  
Paulo N. Martinho
Keyword(s):  
Photoelectron Spectroscopy ◽  
Diazonium Salt ◽  
Pyrolytic Graphite ◽  
Coupling Reaction ◽  
Modified Electrodes ◽  
Current Response ◽  
Highly Oriented Pyrolytic Graphite ◽  
Graphite Electrodes ◽  
Pyrolytic Graphite Electrode ◽  
20 Nm

Reproducible materials that have detection properties towards a certain molecule are very important for applications in the fabrication of devices. Among all the substrates that are used, highly oriented pyrolytic graphite allows to clearly image a monolayer. On the other hand, cryptand molecules are versatile because they can sense certain analytes with high selectivity. The highly oriented pyrolytic graphite electrode was first functionalized with an aryl bearing a bromine or an alkyne group to further attach cryptand molecules to its surface. The functionalization was performed through the electroreduction of aryl diazonium salts. While functionalization with an aryl-bromine produced a 20 nm-thick dendritic layer, functionalization of the surface with an aryl bearing a terminal alkyne produced a 9.7 nm-thick multilayer. However, if the diazonium salt is prepared in situ, a 0.9 nm monolayer with aryl–alkyne groups is formed. The alkyne functionalized electrode reacted with a bromo-cryptand through a Sonogashira C–C coupling reaction yielding electrodes functionalized with cryptands. These were immersed in a solution of a Co(II) salt resulting in Co(II)-cryptate modified electrodes, highlighting the ability of the cryptands’ modified electrode to sense metal ions. The electrode surface was analyzed by X-ray photoelectron spectroscopy after each modification step, which confirmed the successful functionalization of the substrate with both the cryptand and the cryptate. Cyclic voltammetry studies showed stable current response after approximately six cycles. Different reduction processes were detected for both cryptand (−1.40 V vs. SCE) and cryptate (−1.22 V vs. SCE) modified highly oriented pyrolytic graphite.

scholarly journals In Situ Vapor Polymerization of Poly(3,4-ethylenedioxythiophene) Coated SnO2-Fe2O3 Continuous Electrospun Nanotubes for Rapid Detection of Iodide Ions

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2084 ◽  
Author(s):  
Xiuru Xu ◽  
Wei Wang ◽  
Bolun Sun ◽  
Xue Zhang ◽  
Rui Zhao ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Fast Response ◽  
Core Shell ◽  
Current Response ◽  
Electrospinning Technique ◽  
Iodide Ions ◽  
Wide Range ◽  
Vapor Phase Polymerization ◽  
Fe2o3 Nanotubes

In this work poly(3,4-ethylenedioxythiophene) (PEDOT) coated SnO2-Fe2O3 continuous nanotubes with a uniform core–shell structure have been demonstrated for rapid sensitive detection of iodide ions. The SnO2-Fe2O3 nanotubes were firstly fabricated via an electrospinning technique and following calcination process. An in situ polymerization approach was then performed to coat a uniform PEDOT shell on the surface of as-prepared SnO2-Fe2O3 nanotubes by vapor phase polymerization, using Fe2O3 on the surface of nanotubes as an oxidant in an acidic condition. The resultant PEDOT@SnO2-Fe2O3 core-shell nanotubes exhibit a fast response time (~4 s) toward iodide ion detection and a linear current response ranging from 10 to 100 μM, with a detection limit of 1.5 μM and sensitivity of 70 μA/mM/cm2. The facile fabrication process and high sensing performance of this study can promote a wide range of potential applications in human health monitoring and biosensing systems.

scholarly journals Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

2014 ◽  
Vol 10 ◽  
pp. 1354-1364 ◽  
Author(s):  
Melanie Rauschenberg ◽  
Eva-Corrina Fritz ◽  
Christian Schulz ◽  
Tobias Kaufmann ◽  
Bart Jan Ravoo
Keyword(s):  
Molecular Recognition ◽  
Self Assembled Monolayers ◽  
Carbohydrate Binding ◽  
Air Oxidation ◽  
Acetylneuraminic Acid ◽  
Physiological Processes ◽  
Wide Range ◽  
Assembled Monolayers ◽  
Synthetic Carbohydrate ◽  
Derivatives Of

The molecular recognition of carbohydrates and proteins mediates a wide range of physiological processes and the development of synthetic carbohydrate receptors (“synthetic lectins”) constitutes a key advance in biomedical technology. In this article we report a synthetic lectin that selectively binds to carbohydrates immobilized in a molecular monolayer. Inspired by our previous work, we prepared a fluorescently labeled synthetic lectin consisting of a cyclic dimer of the tripeptide Cys-His-Cys, which forms spontaneously by air oxidation of the monomer. Amine-tethered derivatives of N-acetylneuraminic acid (NANA), β-D-galactose, β-D-glucose and α-D-mannose were microcontact printed on epoxide-terminated self-assembled monolayers. Successive prints resulted in simple microarrays of two carbohydrates. The selectivity of the synthetic lectin was investigated by incubation on the immobilized carbohydrates. Selective binding of the synthetic lectin to immobilized NANA and β-D-galactose was observed by fluorescence microscopy. The selectivity and affinity of the synthetic lectin was screened in competition experiments. In addition, the carbohydrate binding of the synthetic lectin was compared with the carbohydrate binding of the lectins concanavalin A and peanut agglutinin. It was found that the printed carbohydrates retain their characteristic selectivity towards the synthetic and natural lectins and that the recognition of synthetic and natural lectins is strictly orthogonal.

scholarly journals Influence of thermal treatment and combustible additives on properties of Latvian clay ceramics pellets

2013 ◽  
Vol 7 (4) ◽  
pp. 175-180 ◽  
Author(s):  
Liga Dabare ◽  
Ruta Svinka
Keyword(s):  
Surface Area ◽  
Ph Value ◽  
Water Solution ◽  
Porous Ceramic ◽  
Mercury Porosimetry ◽  
Environmental Application ◽  
Wide Range ◽  
Different Temperatures ◽  
Ph Level ◽  
Clay Ceramics

Porous ceramic pellets for possible environmental application were produced from different Latvian clays by sintering at different temperatures. Their characteristics and influence of additives were analysed using X-ray diffraction, mercury porosimetry and BET tests. The obtained ceramic pellets from calcareous clays after immersion in distilled water change its pH value, which affects their capability to adsorb ions or molecules on the surface. The sorption capabilities are dependent on the pH level of water solution, composition of clays, and used adsorbate. Porosity of the produced pellets is mostly within range from 15 to 25 % throughout all sintering temperatures with a slight decrease at 1050 ?C. The specific surface area has a wide range up to 30 m2/g. The highest surface area has pellets sintered at lower temperatures. The adsorption capability of pellets was evaluated using water solutions with different ions. The most promising results were obtained with iodine sorption. For most pellets the sorption capacity was 12.7 mg/g, although for the pellets sintered at 1050 ?C it was lower.

scholarly journals Apamin Enhances Neurite Outgrowth and Regeneration after Laceration Injury in Cortical Neurons

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 603
Author(s):  
Hyunseong Kim ◽  
Jin Young Hong ◽  
Junseon Lee ◽  
Wan-Jin Jeon ◽  
In-Hyuk Ha
Keyword(s):  
Phospholipase A2 ◽  
Neurite Outgrowth ◽  
Cortical Neurons ◽  
Neurological Diseases ◽  
Minor Component ◽  
Underlying Mechanism ◽  
Bee Venom ◽  
Dependent Manner ◽  
Neuroprotective Effects ◽  
Wide Range

Apamin is a minor component of bee venom and is a polypeptide with 18 amino acid residues. Although apamin is considered a neurotoxic compound that blocks the potassium channel, its neuroprotective effects on neurons have been recently reported. However, there is little information about the underlying mechanism and very little is known regarding the toxicological characterization of other compounds in bee venom. Here, cultured mature cortical neurons were treated with bee venom components, including apamin, phospholipase A2, and the main component, melittin. Melittin and phospholipase A2 from bee venom caused a neurotoxic effect in dose-dependent manner, but apamin did not induce neurotoxicity in mature cortical neurons in doses of up to 10 µg/mL. Next, 1 and 10 µg/mL of apamin were applied to cultivate mature cortical neurons. Apamin accelerated neurite outgrowth and axon regeneration after laceration injury. Furthermore, apamin induced the upregulation of brain-derived neurotrophic factor and neurotrophin nerve growth factor, as well as regeneration-associated gene expression in mature cortical neurons. Due to its neurotherapeutic effects, apamin may be a promising candidate for the treatment of a wide range of neurological diseases.

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