Experimental Study and Mathematical Modeling of a Glyphosate Impedimetric Microsensor Based on Molecularly Imprinted Chitosan Film

A novel impedimetric microsensor based on a double-layered imprinted polymer film has been constructed for the sensitive detection of the herbicide, glyphosate (GLY), in water. It is based on electropolymerized polypyrrole films, doped with cobaltabis(dicarbollide) ions ([3,3′-Co(1,2-C2B9H11)2]), as a solid contact layer between the gold microelectrode surface and the molecularly imprinted chitosan film (CS-MIPs/PPy/Au). Electrochemical Impedance Spectroscopy (EIS) was used for the characterization of the CS-molecular imprinted polymers (MIPs)/PPy/Au in the presence of GLY concentrations between 0.31 pg/mL and 50 ng/mL. Experimental responses of CS-MIPs/PPy/Au are modeled for the first time using an exact mathematical model based on physical theories. From the developed model, it was possible to define the optimal range of the parameters that will impact the quality of impedance spectra and then the analytical performance of the obtained microsensor. The obtained microsensor shows a low detection limit of 1 fg/mL (S/N = 3), a good selectivity, a good reproducibility, and it is regenerable.

Download Full-text

Electrochemical Impedance Spectroscopy Microsensor Based on Molecularly Imprinted Chitosan Film Grafted on a 4-Aminophenylacetic Acid (CMA) Modified Gold Electrode, for the Sensitive Detection of Glyphosate

Frontiers in Chemistry ◽

10.3389/fchem.2021.621057 ◽

2021 ◽

Vol 9 ◽

Author(s):

Fares Zouaoui ◽

Saliha Bourouina-Bacha ◽

Mustapha Bourouina ◽

Albert Alcacer ◽

Joan Bausells ◽

...

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Gold Electrode ◽

High Selectivity ◽

Electrochemical Impedance ◽

Chitosan Film ◽

Molecularly Imprinted ◽

Cyclic Voltammetry Measurement ◽

Scanning Electron

A novel electrochemical impedance spectroscopy (EIS) microsensor was implemented for the dosage of traces of glyphosate, in real and synthetic water samples. Molecularly imprinted chitosan was covalently immobilized on the surface of the microelectrode previously modified with 4-aminophenylacetic acid (CMA). The characterization of the resulting microelectrodes was carried out by using cyclic voltammetry measurement (CV), scanning electron microscopy (SEM), and electrochemical impedance spectrometry (EIS). EIS responses of the CS-MIPs/CMA/Au microsensor toward GLY was well-proportional to the concentration in the range from 0.31 × 10−9 to 50 × 10−6 mg/mL indicating a good correlation. The detection limit of GLY was 1 fg/mL (S/N = 3). Moreover, this microsensor showed good reproducibility and repeatability, high selectivity, and can be used for the detection of GLY in river water.

Download Full-text

Ampelographic and oenological characterization of the ancient grapevine cv. Dobričić grown in the coastal region of Croatia

OENO One ◽

10.20870/oeno-one.2012.46.4.1530 ◽

2012 ◽

Vol 46 (4) ◽

pp. 263

Author(s):

Goran Zdunić ◽

Irena Budić-Leto ◽

Urska Vrhovsek ◽

Iva Tomić-Potrebuješ ◽

Edi Maletić

Keyword(s):

Coastal Region ◽

Red Wines ◽

High Quality ◽

Virus Incidence ◽

High Virus ◽

First Time ◽

Outstanding Quality ◽

Selection Of

Aims:A four-year study (2007 through 2010) was carried out to determine agronomic, biological, and oenological characteristics of Dobričić grapevines so as to evaluate this cultivar and protect it from extinction.Methods and results: 38 characteristics from the OIV descriptor list were used to describe young shoot, mature leaf, cluster, and berry morphology of Dobričić grapevines. The dimensions of an average leaf were constructed from measured leaf variables. A typical Dobričić genotype at nine microsatellite loci is presented. ELISA analysis revealed high virus incidence and all samples tested were GLRaV-3 positive. The profile of different classes of polyphenols in Dobričić wine was determined using HPLC and spectrophotometry. The concentrations of polyphenols in Dobričić wine, especially anthocyanins, hydroxycinnamic acids and stilbenes, were high compared to major red wines reported in the literature. Descriptive sensory analysis was carried out to determine the aroma attributes describing a Dobričić monovarietal wine.Conclusion: Knowledge of the biodiversity of the grapevine cultivars of Croatia is still scant. This study provides for the first time ampelographic and oenological information on Dobričić grapevines and demonstrates its high quality potential.Significance and impact of the study: The results of the ampelographic characterization would be helpful in the identification and selection of Dobričić for cultivation in certain vine-growing areas. The outstanding quality of Dobričić makes it very promising for wine blending (colour improvement) and plant breeding purposes.

Download Full-text

Raman Scattering Characterization of GaAs-AlAs Superlattices Grown Along the [110] Direction

MRS Proceedings ◽

10.1557/proc-102-169 ◽

1987 ◽

Vol 102 ◽

Author(s):

D. Kirillov ◽

Yi-Ching Pao

Keyword(s):

Raman Scattering ◽

Molecular Beam ◽

Transverse Optical ◽

Crystallographic Structure ◽

Optical Phonons ◽

Lower Intensity ◽

Dominant Feature ◽

First Time

ABSTRACTRaman spectra of the GaAs-AlAs superlattice grown by molecular beam epi-taxy along the [110] direction were studied for the first time. The spectra were compared with spectra of the [100] superlattice and differences due to different crystallographic structure were analyzed. It was found that the energies of folded acoustical modes are higher in the [110] superlattice due to higher sound velocity in the [110] direction. Confined transverse optical phonons were a dominant feature of the spectrum of the [110] superlattice which allowed observation of the folding of transverse optical phonons. Stronger intensity of interface modes and lower intensity of folded acousti-cal modes in the [110] superlattice indicated that the quality of the layer interfaces was worse than in the [100] superlattice.

Download Full-text

Rapid Rubber Extraction and NMR Spectroscopy of Rubber, Extracted from the Endemic Species Scorzonera Tau-Saghyz

Eurasian Chemico-Technological Journal ◽

10.18321/ectj931 ◽

2020 ◽

Vol 22 (1) ◽

pp. 59

Author(s):

K.K. Boguspaev ◽

S.K. Turasheva ◽

T.M. Seilkhanov ◽

D.G. Faleev ◽

M.S. Mutalkhanov ◽

...

Keyword(s):

Adventitious Shoots ◽

Physiological Age ◽

Root Extract ◽

Nmr Characterization ◽

First Time ◽

Rubber Good ◽

Isoprene Rubber

Scorzonera tau-saghyz Lipsch. et G.G. Bosse is an endemic rubber producing plant, growing in mountain regions in South Kazakhstan. The rubber content in plants and the quality of biopolymer has an important impact on industrial rubber production. The results of this study showed that the amount of rubber in S. tau-saghyz roots fluctuates between 7.74% and 38.75%. The amount of synthesized and deposited rubber biopolymer particles depends on various factors such as physiological age of plant, origin, temperature, moisture and environmental conditions. We optimized the extraction method of natural rubber by using n-hexane as a solvent for direct extraction. This method allows extracting the maximum amount of rubber from 3‒4-year-old plants. NMR results show structural links of natural isoprene rubber in the root extract sample. There is a clear relationship between methyl, methine and methylene protons which corresponds to isoprene rubber structure. The samples having strongly marked singlets that are inherent for rubber functional groups confirms the stereospecific structure of rubber. Good solubility of the root extract in deuterated chloroform can characterize the low molecular weight of the polymer. NMR characterization of rubber, extracted from S. tau-saghyz roots, is reported for the first time. Regeneration in vitro provides an important opportunity for endemic preservation by rapidly increasing the number of plants. The best regeneration of adventitious shoots was obtained on MS medium containing 5.5 μM kinetin and 0.5 μM NAA. The plants were successfully acclimatized in a glasshouse with 75% of S. tau-saghyz plantlets, respectively surviving after transfer to ex vitro conditions.

Download Full-text

Mechanical and Chemical Characterization of Hard Anodized Cooker Grids Made in Al-Si Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.813.334 ◽

2019 ◽

Vol 813 ◽

pp. 334-339

Author(s):

Fabio Scherillo ◽

Vincenza Marzocchi ◽

Antonino Squillace ◽

Eugenio Amendola

Keyword(s):

Detrimental Effect ◽

Electrochemical Impedance ◽

Pure Aluminum ◽

Chemical Characterization ◽

Commercially Pure ◽

Alloy Microstructure ◽

A Current ◽

Made In

In the present work the performances of hard anodized component in Al-Si alloy, used as cooker grids, are described in details. The components have been anodized in H2SO4 at low temperature (less than 0 °C) with a current of about 2.4/dm2 A for 70 min.The effect of the alloy microstructure on the quality of the anodized layer is evidentiated, particularly the Si rich intermetallics inside the metal have a detrimental effect on the performance of the oxidized layer.The components have been analyzed by means of nano-indentation to evaluate the mechanical behavior of the layer. The chemical performances have been studied using Electrochemical Impedance Spectroscopy in different solutions (0.05 M Na2SO4 and 0.01 M NaOH). The results obtained have been correlated with the microstructure of the alloy, furthermore all test have been done, for comparison, on Commercially Pure Aluminum anodized in the same conditions of the Al-Si components.The results indicate that the mechanical properties of the anodized layer of Al-Si components are lower to respect that of Commercially Pure Aluminum.On the contrary the chemical resistance of Al-Si anodized items result poor compared to Commercially Pure Aluminum, in particular the oxidized layer is subject to degradations due to the presence of Si rich inclusions.

Download Full-text

Characterization of the Silicon / Fluoride Solution Interface by In-Situ Microwave Reflectivity

MRS Proceedings ◽

10.1557/proc-451-197 ◽

1996 ◽

Vol 451 ◽

Author(s):

Arun Natarajan ◽

Gerko Oskam ◽

Douglas A. Oursler ◽

Peter C. Searson

Keyword(s):

Electrochemical Impedance ◽

Surface States ◽

Active Surface ◽

Potential Region ◽

Flat Surfaces ◽

Solution Interface ◽

Valence Bands

ABSTRACTEtching of silicon in aqueous fluoride solutions can lead to almost atomically flat surfaces with a low density of surface states and recombination centers. The final quality of the surface, however, is strongly dependent on the solution composition and pH. We have performed electrochemical impedance spectroscopy in combination with potential modulated microwave reflectance spectroscopy (PMMRS) to elucidate the processes occurring at the surface during etching. PMMRS is a novel technique that only probes the free carriers in the conduction and valence bands and is, under certain conditions, not affected by processes involving electrically active surface states or charge transfer. This unique feature allows us to separate the energetics of the semiconductor from surface processes. Microwave reflectivity (δR) versus potential curves in HF solutions demonstrate the variation of the flatband potential as a function of pH. The AR response in the narrow potential region around the flatband potential and at more negative potentials is also discussed.

Download Full-text

PPIP5K2 and PCSK1 are Candidate Genetic Contributors to Familial Keratoconus

Scientific Reports ◽

10.1038/s41598-019-55866-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 10

Author(s):

Mariam Lofty Khaled ◽

Yelena Bykhovskaya ◽

Chunfang Gu ◽

Alice Liu ◽

Michelle D. Drewry ◽

...

Keyword(s):

Gene Trap ◽

Whole Exome ◽

The Us ◽

Related Quality ◽

First Time

AbstractKeratoconus (KC) is the most common corneal ectatic disorder affecting >300,000 people in the US. KC normally has its onset in adolescence, progressively worsening through the third to fourth decades of life. KC patients report significant impaired vision-related quality of life. Genetic factors play an important role in KC pathogenesis. To identify novel genes in familial KC patients, we performed whole exome and genome sequencing in a four-generation family. We identified potential variants in the PPIP5K2 and PCSK1 genes. Using in vitro cellular model and in vivo gene-trap mouse model, we found critical evidence to support the role of PPIP5K2 in normal corneal function and KC pathogenesis. The gene-trap mouse showed irregular corneal surfaces and pathological corneal thinning resembling KC. For the first time, we have integrated corneal tomography and pachymetry mapping into characterization of mouse corneal phenotypes which could be widely implemented in basic and translational research for KC diagnosis and therapy in the future.

Download Full-text

Separation of baculoviruses using molecularly imprinted polymer hydrogels

MRS Proceedings ◽

10.1557/proc-787-g3.1 ◽

2003 ◽

Vol 787 ◽

Author(s):

Linden D.V. Bolisay ◽

John F. March ◽

William E. Bentley ◽

Peter Kofinas

Keyword(s):

Animal Health ◽

Crop Protection ◽

Recombinant Baculovirus ◽

Imprinted Polymer ◽

Molecular Imprinted Polymers ◽

Molecularly Imprinted ◽

Polymer Hydrogels ◽

Aqueous Environments ◽

Biological Analytes

ABSTRACTThe goal of this research is to develop molecular imprinted polymers (MIP) for biomimetic recognition of viruses. Our experimental results indicate that hydrogels can be produced, which can specifically and selectively bind recombinant baculoviruses. Although it is expected that imprinted cavities will be distorted due to the swelling of the hydrogel in water, our experiments show that even the swollen gels exhibit remarkable affinity toward recombinant baculovirus. The proposed methodologies for the synthesis and characterization of MIPs thus offer exciting avenues for the development of virus recognition techniques. The virus MIPs must function in aqueous environments. Our approach employs a more flexible non-covalent imprinting method, starting from a readily available polyamine polymer, and both MIP synthesis and testing are performed in aqueous solutions. The development of a virus imprinted MIP, which would apply to the identification, classification, and removal of viruses. This is currently a very difficult task, but the need is widespread in diverse sectors, including national security, human and animal health, crop protection, and biologics production. The development of general methods using MIPs capable of specific recognition of biological analytes would have an enormous value in medicine and bioanalytics.

Download Full-text

The importance of using hydrogen evolution inhibitor during the Zn and Zn-Mn electrodeposition from ethaline

Journal of the Serbian Chemical Society ◽

10.2298/jsc190718084b ◽

2019 ◽

Vol 84 (11) ◽

pp. 1221-1234 ◽

Cited By ~ 1

Author(s):

Mihael Bucko ◽

Milorad Tomic ◽

Miodrag Maksimovic ◽

Jelena Bajat

Keyword(s):

Hydrogen Evolution ◽

Electrochemical Impedance ◽

Choline Chloride ◽

Deep Eutectic Solvent ◽

Corrosion Stability ◽

Zinc Electrodeposition ◽

Current Densities ◽

The Stability ◽

First Time

Cyclic voltammetry was used for the characterization of zinc electrodeposition on steel from ethaline deep eutectic solution (1:2 choline chloride: ethylene glycol). The influence of 4-hydroxy-benzaldehyde (HBA) as an additive was analyzed. It was shown that hydrogen evolution is inhibited in the presence of HBA and further significantly retarded upon addition of Zn2+ to the solution containing HBA. The cathodic peak for Zn2+ reduction in this type of ionic liquid (ethaline+HBA+Zn2+) resembles the zinc reduction in aqueous solution. The corrosion resistance of Zn coatings deposited at different current densities was evaluated by electrochemical methods, i.e., polarization measurements and electrochemical impedance spectroscopy in 3 % NaCl solution. The possibility of Zn?Mn alloy deposition from ethaline deep eutectic solvent was investigated for the first time. In addition, the corrosion stability of these alloy coatings was analyzed and compared to the stability of bare Zn coatings. It was shown that the optimum deposition current density for both Zn and Zn?Mn coatings with increased corrosion stability from ethaline + HBA electrolyte is 5 mA cm?2.

Download Full-text

Metal/GaAs interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154202 ◽

1989 ◽

Vol 47 ◽

pp. 446-447

Author(s):

C. Barry Carter ◽

Jane G. Zhu ◽

C. J. Palmstrøm

Keyword(s):

Rare Earth ◽

Earth Metal ◽

Contact Layer ◽

Dimensional Structure ◽

Misfit Dislocations ◽

Additional Advantage ◽

3 Dimensional ◽

Zinc Blende

Reactions between III-V compound semiconductors and metals occur during the formation of Ohmic or Schottky contacts for semiconductor devices. Since the products of such reactions usually have crystal structures different from the zinc-blende structure of GaAs, it is necessary to understand the structure of the metal/GaAs interface in order to optimize the quality of the contact. At low temperatures, ternary phases given of the form, MxGaAs, grow during the metal-GaAs reactions. Well-documented examples are given by Ni-GaAs and Co-GaAs reactions. These ternary phases are thermodynamically unstable and decompose to MyGa and MzAs at higher temperatures. For contacts involving rare-earth metals, such as Er, Tb and Dy, on GaAs, a substantial interface chemical reaction has been found in which GaAs is dissociated and a more than 12Å-thick rare-earth arsenide interfacial layer is formed. In order to improve the reliability of these contacts and to control the reactions which take place at the GaAs interface, intermetallic compounds, NiAl and CoGa, and rare-earth metal arsenides, YbAs and ErAs, have recently been grown epitactically on GaAs. The work described here has concentrated on the characterization of the compound/GaAs interfaces formed during this process, paying particular attention to the structure of the misfit dislocations present at the interface. An additional advantage of this approach is that, if the quality of the contact layer is sufficiently high, it might be possible to grow a second high-quality layer of GaAs on top and thus begin to generate a 3-dimensional structure.

Download Full-text