Electroactive Compounds Research Articles

Real-time measurement of tumour hypoxia using an implantable microfabricated oxygen sensor

Hypoxia commonly occurs within tumours and is a major cause of radiotherapy resistance. Clinical outcomes could be improved by locating and selectively increasing the dose delivered to hypoxic regions. Here we describe a miniature implantable sensor for real-time monitoring of tissue oxygenation that could enable this novel treatment approach to be implemented. The sensor uses a solid-state electrochemical cell that was microfabricated at wafer level on a silicon substrate, and includes an integrated reference electrode and electrolyte membrane. It gave a linear response to oxygen concentration, and was unaffected by sterilisation and irradiation, but showed susceptibility to biofouling. Oxygen selectivity was also evaluated against various clinically relevant electroactive compounds. We investigated its robustness and functionality under realistic clinical conditions using a sheep model of lung cancer. The sensor remained functional following CT-guided tumour implantation, and was sufficiently sensitive to track acute changes in oxygenation within tumour tissue.

Theoretical evaluation of electroanalitical determination of diazoline (mebhydrolin) on a polymer electrode

Mebhydrolin, the active substance of diazoline, is a histamine H1-blocker that possesses the anti-allergic, anti-pruritic, antioxidative properties as well as weak sedative effect. It is used to treat diseases and pathological conditions. Its long-term and excessive use leads to different side effects and complications such as granulocytopenia, neutropenia, dyscrasia, and granulocytosis. That is why the development of effective methods for determining the concentration of this drug is vital. There are no reports to date available on the electrochemical determination of diazoline (mebhydrolin). Based on the structural characteristics of the molecule it can be concluded that it is an electroactive compound. Its oxidation can effectively occur on the conductive polymer layer. Moreover, the electrochemical behavior of the drug promises to be very interesting, as it is developed by a complicated mechanism. In this work, the electrochemical determination of a mebhydrolin concentration on the leading polymer was studied from a theoretical point of view. The polymerization and the reactions sequences was describe by a mathematical model, which was derived and analyzed using linear stability theory and bifurcation analysis. From the model analysis we concluded that: a). The polymer electrode promotes an electrooxidation of mebhydrolin and the system is electroanalytically effective. The relationship between the electrochemical parameter (the current) and the concentration of nitrite is described and it is linear in nature. Therefore, the analytical signal can be easily interpreted. b). The electroanalytical process occurs in the diffusion mode at low concentrations of the analyte and in the adsorption mode at high concentration. c). The oscillatory behavior of this system is possible. It is caused by the effects of the electrochemical stage on PES as well as also by surface instabilities.

New and sensitive magnetic carbon paste electrode for voltammetry determination of morphine and methadone

A novel and sensitive modified magnetic carbon paste electrode (MMCPE) is introduced. Magnetic carbon paste electrode (MCPE) was fabricated by a ring magnet that was put behind an insulin syringe packed with a mixture of graphite powder, multi-walled carbon nanotube (MWCNT), and paraffin oil. The surface of the MCPE was modified by immersing the electrode in a suspension of nanomagnetic core-shell (Fe3O4@SiO2) for 20 s, while nanomagnetic core-shells were physically adsorbed on the surface of the electrode by the magnetic force. The electrochemical behavior of morphine and methadone was studied at this new modified electrode. The efficiency of MMCPE was compared with a simple CPE and two modified CPEs prepared by mixtures of (graphite + MWCNT) and (graphite + MWCNT + nanomagnetic core-shell). The results showed that the sensitivity of MMCPE was higher than the three other CPEs. As a result, direct attachment of Fe3O4@SiO2 magnetic nanoparticles to the surface of the CPE by the magnetic force showed much higher surface area and electrode sensitivity compared to when the NPs were mixed with other compounds. Our studies showed this electrode is not selectable and can be used as a general electrode for all electro-active compounds. The electro-active surface area of MMCPE was obtained by Randles–Sevcik equation. Square wave voltammetry (SWV) was applied for determination of morphine and methadone in a linear range of 5.0 × 10–9 to 1.8 × 10–6 M and 1.0 × 10–8 to 8.0 × 10–6 M, with detection limits of 1.6 nM and 3 nM, respectively. Eventually, the proposed electrode was applied to determine morphine and methadone in urine samples.

Sensor based on redox conjugated poly(para-phenylene) for the simultaneous detection of dopamine, ascorbic acid, and uric acid in human serum sample.

An electrochemical sensor for the individual and the simultaneous detection of dopamine (DA), ascorbic acid (AA), and uric acid (UA) based on redox conjugated "poly(para-phenylene)" (Fc-ac-PPP) bearing ferrocene and carboxylic acid in lateral position has been developed. The electrochemical characterization of the sensor has been studied with cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). We highlighted that the catalytic activity of the Fc-ac-PPP polymer provided by its redox electrochemical properties and chemical structure allows the electrochemical detection of DA, AA, and UA. We demonstrated that the sensor provides high sensitivity and selective signal in the coexistence of DA, AA, and UA within a short time. Low detection limits and wide linear ranges of detection have been demonstrated respectively for DA 3 × 10-10M (1nM-10μM), AA 1.6 × 10-8M (0.1μM-1mM), and UA 1 × 10-8M (0.1μM-1mM). In addition, the sensor has been successfully applied to determine DA in urine and human serum samples even in the presence of high concentrations of AA and UA. This sensor could be a powerful device for the detection of other electroactive compounds thanks to its high catalytic properties and chemical structure. Graphical abstract.

Pairing Cross-Linked Polyviologen with Aromatic Amine Host Structure for Anion Shuttle Rechargeable Batteries.

Electroactive organic compounds could bring new chemical opportunities to further improve existing electrochemical energy-storage technologies as they can be prepared from less-limited resources and potentially at low environmental footprint. Among the current explored research fields, the anion-ion cell configuration appears poorly investigated although quite promising to promote the fabrication of molecular (metal-free) rechargeable batteries. Herein, we report the synthesis and the electrochemical behavior of both Mg/Li salts of 2,5-(dianilino)terephthalate (MgDAnT and Li2 DAnT) and cross-linked polyviologen (c-PV2+ ) that can reversibly uptake/extract anions at different working potentials, enabling the assembly of full anionic organic batteries. The reversible anion ingress in MgDAnT is however accompanied by solvent co-insertion from the electrolyte that provokes an overpotential effect during the first charge. Full anionic batteries pairing Li2 DAnT with c-PV2+ were assembled giving rise to 0.7 V as output voltage with a specific capacity of 50 mAh per gram of Li2 DAnT.

Fabrication of a cell-recognition/electron-transfer/cross-linker, peptide-immobilized electrode for the sensing of K562 cells

We designed an electrode that has the ability to sense a target cell. This new electrode is intended for use in cell recognition via electron-transfer and cross-linker peptide immobilization. Myelopeptide-4 (MP-4:FRPRIMTP) is a marrow-origin peptide that interacts with receptors of the human leukemia cell line (K562 cells), and allows their differentiation. The YYYYC electron-transfer peptide improves the electron-transfer accessibility from an electroactive compound to an electrode. Oligoalanine plays the role of a cross-linker that immobilizes a peptide series (Ac-FRPRIMTPYYYYCAAAAA) to collagen, which then allows it to be cast onto an electrode. Use of the electrode with a peptide increased the peak currents of [Fe(CN)6]4-/3- and also improved the reversibility of redox. These improvements are due to the interaction between [Fe(CN)6]4-/3- and the peptide. When electrochemical impedance spectroscopy (EIS) measurements were carried out using a collagen/peptide probe-immobilized electrode, the electron transfer resisitance was lower than that without the peptide. The detection of K562 cells was based on an increase in resistance, because MP-4 was bound to the receptors on the cell surface. The responses were linear and ranged in number from 27 to 2,000 cells/mLwith a detection limit of 8 cells/mL. Recoveries of 50 and 1,000 cells/mL in human serum were accomplished at rates of 98 and 101%, respectively. Consequently, the proposed procedure is a powerful new concept for cytosensing.

Opportunities and Challenges for Organic Electrodes in Electrochemical Energy Storage.

As the world moves toward electromobility and a concomitant decarbonization of its electrical supply, modern society is also entering a so-called fourth industrial revolution marked by a boom of electronic devices and digital technologies. Consequently, battery demand has exploded along with the need for ores and metals to fabricate them. Starting from such a critical analysis and integrating robust structural data, this review aims at pointing out there is room to promote organic-based electrochemical energy storage. Combined with recycling solutions, redox-active organic species could decrease the pressure on inorganic compounds and offer valid options in terms of environmental footprint and possible disruptive chemistries to meet the energy storage needs of both today and tomorrow. We review state-of-the-art developments in organic batteries, current challenges, and prospects, and we discuss the fundamental principles that govern the reversible chemistry of organic structures. We provide a comprehensive overview of all reported cell configurations that involve electroactive organic compounds working either in the solid state or in solution for aqueous or nonaqueous electrolytes. These configurations include alkali (Li/Na/K) and multivalent (Mg, Zn)-based electrolytes for conventional "sealed" batteries and redox-flow systems. We also highlight the most promising systems based on such various chemistries relying on appropriate metrics such as operation voltage, specific capacity, specific energy, or cycle life to assess the performances of electrodes.

Application of carboxylic acid-functionalized of graphene oxide for electrochemical simultaneous determination of tryptophan and tyrosine in milk

In this work, a new method for the simultaneous determination of tryptophan (Trp) and tyrosine (Tyr) in milk has been reported. Trp and Tyr are essential amino acids in human nutrition, but their electrochemical signal overlapped. For solve this problem, we developed modified Screen Printed Carbon Electrode (SPCE) with Graphene Oxide–COOH/Chitosan (GO–COOH/Chitosan) electro-deposition. The morphology and electrochemical performance of modified electrode were characterized by scanning electron microscopy, energy dispersive spectrometry, FT-IR, electrochemical impedance spectroscopy and cyclic voltammetry. The electrochemical simultaneous determination of Trp and Tyr has been investigated by using differential pulse voltammetry. The carboxylic acid functionalized GO modified SPCE was utilized to catalyze the oxidation of Trp and Tyr. Compared with SPCE/GO/Chitosan and SPCE/Chitosan sensor, the new sensor has enhanced sensitivity, low detection limit and high selectivity. In addition, the SPCE/GO–COOH–Chitosan sensor enhanced separation of the oxidation peak of Tyr and Trp and showed a remarkable increase in peak current for electro-active compounds, thus, it can be used for simultaneous voltammetric determination. Under the optimized experimental conditions, a linear correlation between oxidation peak current and concentration of Tyr and Trp in the ranges 0.1–60 µM and 0.4–40 µM with a detection limit of 0.05 µM (S/N = 3) and 0.1 µM (S/N = 3) were achieved, respectively. Finally, the proposed electrochemical sensor was applied for quantification of Tyr and Trp in milk samples, where standard solutions were spiked to the milk samples and recoveries were obtained.

Assay of Phospholipase D Activity by an Amperometric Choline Oxidase Biosensor.

A novel electrochemical method to assay phospholipase D (PLD) activity is proposed based on the employment of a choline biosensor realized by immobilizing choline oxidase through co-crosslinking on an overoxidized polypyrrole film previously deposited on a platinum electrode. To perform the assay, an aliquot of a PLD standard solution is typically added to borate buffer containing phosphatidylcholine at a certain concentration and the oxidation current of hydrogen peroxide is then measured at the rotating modified electrode by applying a detection potential of +0.7 V vs. SCE. Various experimental parameters influencing the assay were studied and optimized. The employment of 0.75% (v/v) Triton X-100, 0.2 mM calcium chloride, 5 mM phosphatidylcholine, and borate buffer at pH 8.0, ionic strength (I) 0.05 M allowed to achieve considerable current responses. In order to assure a controlled mass transport and, at the same time, high sensitivity, an electrode rotation rate of 200 rpm was selected. The proposed method showed a sensitivity of 24 (nA/s)⋅(IU/mL)−1, a wide linear range up to 0.33 IU/mL, fast response time and appreciable long-term stability. The limit of detection, evaluated from the linear calibration curve, was 0.005 IU/mL (S/N = 3). Finally, due to the presence of overoxidized polypyrrole film characterized by notable rejection properties towards electroactive compounds, a practical application to real sample analysis can be envisaged.

Effect of Molecular Structure of Quinones and Carbon Electrode Surfaces on the Interfacial Electron Transfer Process

Quinones can undergo thermodynamically reversible proton-coupled electron transfer reactions and are being applied as electroactive compounds in aqueous organic batteries. However, the electrochemi...

Infrageneric phylogenetics investigation of Chimonanthus based on electroactive compound profiles

Voltammetric scan can record the profile of electrochemical active substances in plant tissues. Because the distribution of chemical components in plants is controlled by genes, these profiles can reflect differences at the genetic level in different species. In this study, the voltammetric scan was applied to the investigation of macrophanerophytes taxonomy. All species of Chimonanthus with two exotaxa were deliberately selected due to their controversial infrageneric relationship. Electrode surface modification was excluded in this work to improve the convenience and accuracy of the fingerprint recording process. The dendrogram deduced from the electrochemical fingerprint data suggests that Ch. Zhejiangensis and Ch. grammatus are two groups of Ch. nitens, which may be only the ecotype of Ch. nitens, rather than independent taxonomic species. The small variations between the three species may be due to environmental factors and cannot be used for species formation. In addition, Ch. campanulatus and Ch. Praecox were clustered together with a close relationship.

Electrochemical Behavior and LC-MS Analysis of Anthocyanin’s in Vaccinium Arctostaphylos L. Extract: The Molecular Modelling of Potential Inhibition to COVID-19 and ROS Generation Receptors

Caucasian whortleberry (Vaccinium Arctostaphylos L.) is rich in anthocyanins, which possesses a wide range of biological and pharmaceutical activities. Electrochemical behavior of V. Arctostaphylos extract of dried fruit was performed by cyclic voltammetry and differential pulse voltammetry in aqueous solution. The results show that the level of delphinidin 3-O-glucoside (D3-OG) compound is higher than petunidin 3-O-glucoside (P3-OG) and malvidin 3-O-glucoside (M3-OG) level. This extract has a high solubility in water, and the potential-pH diagram indicates that the D3-OG capable oxidized to D3-OGOX with two electron/two proton process. D3-OG compound has a high antioxidant power because of the oxidation peak potential is low. Furthermore, total antioxidant capacity (1.475 C g−1) was determined by charges under of first oxidation peak. The antioxidant activity of three anthocyanins against Xanthine oxidase, Myeloperoxidase, NADPH oxidase, cytochrome P450 3A4 and 2B4 (ROS generation enzymes) has been performed through molecular docking studies. The results indicated that all the anthocyanins (D3-OG, P3-OG and M3-OG) bound exclusively to the binding site of ROS generation enzymes and have a remarkable role in suppressing the destructive effects of oxidative stress in the biological system of the human body. Also, D3-OG as a major anthocyanin of Vaccinium Arctostaphylos L. extract has an inhibition effect against the COVID-19 outbreak. Electrochemical approaches provided a simple, fast, low cost, green, and high sensitivity methods for investigation of electroactive compounds in plant extracts.

Differential Pulse Voltammetric Determination of Paracetamol Using Activated Glassy Carbon Electrode

The electrochemical property of paracetamol was researched in detail at a smooth carbon terminal and enacted lustrous carbon anode. Cyclic voltammetry and differential heartbeat voltammetry were utilized as indicative procedures in the assurance of paracetamol. The AGCE showed amazing electro-synergist conduct for the oxidation of PAR as proven by the improvement of the oxidation top current and the move in the oxidation top potential to more negative qualities by (13mv) in correlation with an uncovered GCE. In the current work the enacted lustrous carbon anode was set up by actuating 200 s in a period base strategy at a capability of 1750 mV. The terminal cycle of paracetamol was contemplated and some the test boundaries which influence the reaction paracetamol, for example, pH, impact of PAR fixation and output rate on AGC anode. The examination of cyclic voltammogram gave key electrochemical boundaries including the electroactive surface inclusion ( ), the electron move coefficient ( ) and the heterogeneous rate steady (ks). The condition of the adjustment bend was discovered to be: Ip( A) =0.429C ( M) + 6.43, R2=0.993. The LOD and LOQ for the created technique were resolved to be 8×10-8 mol L-1 and 2.6×10-7mol L-1 individually. Medication control has been on the worldwide plan for more a century on the planet. In this way, drug examination is a significant instrument for drug definitions which has extraordinary effect on general wellbeing. Consequently, the advancement of basic, touchy and quick strategy to decide the dynamic fixings in medications appears to be fundamental. From the ecological perspective, drugs including anti-toxins are another gathering of synthetic compounds of concern entering the climate at focuses with the end goal that their wellbeing impacts are obscure. Thus, paracetamol is one of the anti-toxin medicates that used to battle contaminations brought about by microscopic organisms or different microorganisms. Paracetamol, N-(4-hdroxyphenyl) acetamide is a generally utilized pain relieving and antipyretic medication. It is perhaps the most famous and generally utilized medications for the treatment of agony and decrease of fever. It possesses a remarkable situation among pain relieving drugs. For the most part, paracetamol doesn't display any destructive results, because of its quickly and totally used. In any case, the overdose of paracetamol can prompt the gathering of toxics metabolites, which may cause liver issue, kidney harm, skin rashes and provocative of the pancreas. Paracetamol portrayed as 4-hydroxyacetanlide or N-acetyl-p-aminophenol is known as acetaminophen and its synthetic equation, C8H9NO2. These days, Paracetamol is broadly utilized for its noteworthy remedial attributes consequently exact assurance and control of its quality is significant. The advancement of straightforward, delicate and exact electroanalytical techniques for the assurance of paracetamol is significant. The different methods have been utilized for the assurance of paracetamol in the body liquids and drugs arrangements including spectroscopy, chromatography, titrimetry and chemiluminscence. Notwithstanding, the greater part of these procedures experience the ill effects of certain disservices like; significant expense, require extraction measure, long investigation time, necessity for test pre-treatment which is tedious control steps, need exceptional preparing, versatile, modern instrument and making them inadmissible for routine examination and furthermore these strategies normally includes hydrolysis of paracetamol test to 4-aminophenol, which the necessary the development of a hued complex utilizing a suitable reagent, which sets aside a long effort to perform. Then again electrochemistry offers various appealing favorable circumstances, for example, ease, simple to control, compact and quick. It has been broadly utilized in natural networks, drug and a few medications containing tertiary amine useful gathering, because of its continuation, affectability, reproducibility and selectivity towards many objective analytes. Paracetamol is an electroactive compound (contains hydroxyl and NH bunches on its fragrant rings) and can be oxidized under reasonable conditions, the utilization of electrochemical discovery can be viewed as fitting because of its quick reaction and high affectability. Numerous papers have been distributed about the electrochemical assurance of paracetamol dependent on its oxidation conduct with various cathodes, for example, C60-changed polished carbon anode, Poly (4-vinyl pyridine) multi walled carbon nanotubes adjusted shiny carbon terminal, lustrous carbon cathode, screen printed graphene terminal, gold nanoparticles cathodes, Bismuth oxide altered smooth carbon anode and Ni-adjusted anode. These reports indicated great identification cutoff points and affectability yet, the principle disadvantage is the need of additional time through the burning-through change measure which typically includes a few stages to join the modifier to the substrate and furthermore the expenses. In this paper, no examination has been accounted for assurance of paracetamol utilizing initiated smooth carbon cathode.

Rational engineering of Aerococcus viridansl-lactate oxidase for the mediator modification to achieve quasi-direct electron transfer type lactate sensor

The l-lactate oxidase (LOx) based lactate sensors are widely used for clinical diagnostics, sports medicine, and food quality control. However, dissolved oxygen interference and electroactive interferent effects are inherent issues of current lactate sensors. In this paper, a quasi-direct electron transfer (quasi-DET) type lactate sensor was developed using rationally engineered Aerococcus viridans LOx (AvLOx) modified with amine-reactive phenazine ethosulfate (PES). Since the modification of wild type AvLOx by PES did not result quasi-DET, engineered AvLOx with additional Lys residue was designed. The additional Lys residue was introduced by substituting residue locating on the surface of AvLOx, and within 20 Å of the isoalloxazine ring of FMN. Among several constructed mutants, Ala96Leu/Asn212Lys double mutant showed the highest dye-mediated dehydrogenase activity with negligible oxidase activity, showing quasi-DET properties after PES modification, when the enzyme was immobilized on screen printed carbon electrode. The constructed electrode did not show oxygen interference in cyclic voltammetric analysis and distinct catalytic current with 20 mM l-lactate. The sensor performance of a chronoamperometric l-lactate sensor employing PES modified Ala96Leu/Asn212Lys AvLOx, marked with linear range between 0 and 1 mM, with sensitivity of 13 μA/mM∙cm2, and a limit of detection of 25 μM for l-lactate. By applying −200 mV vs. Ag/AgCl, l-lactate could be monitored with negligible interference from 170 μM ascorbic acid, 1.3 mM acetaminophen, 1.4 mM uric acid or 20 mM glucose. These results indicated that a quasi-DET type lactate sensor was developed that did not suffer from the interference of oxygen and representative electroactive ingredient compounds.

Voltammetric determination of prifinium bromide in a pharmaceutical formulation

For the first time voltammetric methods have been applied and optimized for prifinium bromide (PRF) determination in pharmaceutical formulation. Cyclic voltammetry (CV) study has shown that PRF is an electroactive compound with quasi-revisable voltammograms. Optimization of voltammetric parameters indicated that platinum is the proper working electrode and (KNO3 1 M) is the proper supporting electrolyte. All applied voltammetric methods have shown high precession and accuracy. Square wave voltammetry (SWV) has shown the best limit of detection and limit of quantitation of 45.6 and 58.1 µg mL−1, respectively. Recoveries of SWV are 99.06% and 98.60% for 0.30 and 0.60 mg mL−1, respectively, using PRF tablet Riabal® 30 mg. CV with relative standard deviation values of 0. 135 and 0.322 of intra-day repeatability and inter-day reproducibility, respectively, has the best precision.

Nanoparticle Doped PEDOT for Enhanced Electrode Coatings and Drug Delivery.

In order to address material limitations of biologically interfacing electrodes, modified silica nanoparticles are utilized as dopants for conducting polymers. Silica precursors are selected to form a thiol modified particle (TNP), following which the particles are oxidized to sulfonate modified nanoparticles (SNPs). The selective inclusion of hexadecyl trimethylammonium bromide allows for synthesis of both porous and nonporous SNPs. Nonporous nanoparticle doped polyethylenedioxythiophene (PEDOT) films possess low interfacial impedance, high charge injection (4.8 mC cm-2 ), and improved stability under stimulation compared to PEDOT/poly(styrenesulfonate). Porous SNP dopants can serve as drug reservoirs and greatly enhance the capability of conducting polymer-based, electrically controlled drug release technology. Using the SNP dopants, drug loading and release is increased up to 16.8 times, in addition to greatly expanding the range of drug candidates to include both cationic and electroactive compounds, all while maintaining their bioactivity. Finally, the PEDOT/SNP composite is capable of precisely modulating neural activity in vivo by timed release of a glutamate receptor antagonist from coated microelectrode sites. Together, this work demonstrates the feasibility and potential of doping conducting polymers with engineered nanoparticles, creating countless options to produce composite materials for enhanced electrical stimulation, neural recording, chemical sensing, and on demand drug delivery.

A Sensitive Voltammetric Biosensor forEscherichia ColiDetection Using an Electroactive Substrate for $\beta$ -D-Glucuronidase

In this paper, we developed a sensitive and simple electrochemical method for the rapid detection of Escherichia coli in water samples. The general principle of the assay utilizes the enzyme $\beta $ -D-glucuronidase. This enzyme was induced by adding methyl- $\beta $ -D-glucuronide sodium salt and its activity promoted the cleavage of 8-hydroxyquinoline glucuronide to the electroactive compound 8-hydroxyquinoline. This cleavage product was further oxidized on the working electrode of a potentiostat using cyclic voltammetry. The obtained current output signal in a specific voltage range (400 to 600 mV) indicated enzyme activity and subsequently was an evidence for E. coli cells in the sample. For our experiment, we designed a low-cost potentiostat and show an evaluation of this instrument. First, the $\beta $ -D-glucuronidase assay was tested with various concentrations of enzyme solutions before living E. coli cells were investigated. Our presented method allowed a clear and a sensitive identification of 1 colony-forming unit of E. coli without any interference from other investigated bacterial strains. Comprising only few working steps (filtration, incubation, and voltammetric analysis), the method allowed incorporation into an automated prototype that delivered results similar to those obtained from samples treated in laboratory.

Electrochemically initiated co-polymerization of monomers of different oxidation potentials for molecular imprinting of electroactive analyte

Herein, we report an electrochemically initiated co-polymerization of two electroactive monomers of different oxidation potentials. The molar ratio of low oxidation potential monomer in the solution for electropolymerization was optimized to find condition suitable for co-polymerization of high-oxidation potential monomer effectively at lower oxidation potential. The XPS analysis confirmed successful co-polymerization. This co-polymerization condition was further used in imprinting of melatonin, an electroactive compound. Entrapment of melatonin in the polymer matrix was confirmed by measuring electroactivity of melatonin in the 0.1 M KCl−HCl solution (pH 1.6). This MIP based electrochemical sensor determined melatonin in the linear dynamic concentration range 10–80 μM. Detectability of proposed chemosensor was 0.14 μM (S/N = 3). The mean RSD for the concentration range studied was ∼20%. Selectivity of the chemosensor was satisfactory towards common structural analogues and biomolecules. Furthermore, the chemosensor was successfully used to determine melatonin in real samples. The sensitivity in the presence of matrix components and that for the KCl−HCl solution were quite similar. The results obtained indicate the suitability of the devised chemosensor for practical applications.

Lycoris species identification and infrageneric relationship investigation via graphene enhanced electrochemical fingerprinting of pollen

The electrochemical activity profile of plant tissue shows a unique fingerprint related to the phylogenetic position of plant species. The assistance of graphene in plant extract adsorption and plant tissue embedding distinctly enhances signal sensitivity using a chip-based portable electrochemical fingerprint recording process. We converted fingerprints recorded under different conditions to recognizable patterns and colours for reliable plant identification. The type and content of electroactive compounds in plants are controlled by genes, so the degree of their differences can be used to reflect genetic differences and subsequently used for studying taxonomic relationships. We then proposed an electro-chemotaxonomical methodology based on multiple fingerprints. Pollens of 17 Lycoris species have been used as a model subject for electro-chemotaxonomical investigation of their infrageneric relationships, and the results have been compared with those of palynological studies. The results are more persuasive than those of classical chemotaxonomic studies and are satisfactorily correlated with taxonomic levels. Due to the extremely low-cost and fast analysis process compared with modern molecular-based taxonomic methods, we believe this technology could play a great role as an assistive technology in the future of phylogenetic studies.

Carbon Paste Modified Electrode as Powerful Sensor Approach Determination of Food Contaminants, Drug Ingredients, and Environmental Pollutants: A Review

Background:Application of electrochemical sensors for analysis of food, biological and water polluting compounds helps to speed up their analysis in the real samples. Electrochemical sensors with low cost, fast response and portable ability are a better choice compared to traditional methods for analysis of electro-active compounds such as HPLC. Therefore, in recent years, many analytical scientists have suggested this type of analytical method for analysis of food, biological compounds and water pollutants.Objective:Due to low cost, easy modification and low non-faradic current, the carbon paste electrode is a suitable choice as a working electrode in the electrochemical and especially voltammetric analysis. On the other hand, modification of carbon paste electrode can improve the quality of the sensor for the analysis of electroactive compounds at nanomolar level.