Detection of Senecionine in Dietary Sources by Single-Use Electrochemical Sensor

Pyrrolizidine alkaloids (PAs) are produced by plants as secondary compounds that are the most widely distributed natural toxins. There have been many cases of human toxicity caused by consumption of toxic plant species, as herbal teas and grain or grain products contaminated with PA-containing seeds have been reported. Companies that produce dried spices and tea leaves should examine the PA level in their products. For the first time in the literature, a simple and inexpensive electrochemical assay based on a single-use sensor was introduced for quantitative determination of senecionine (SEN) in the most frequently contaminated food sources. SEN was immobilized on a pencil graphite electrode surface by the passive adsorption technique. Differential pulse voltammetry (DPV) was used to evaluate the oxidation signal of SEN, which was observed to be around +0.95 V. The oxidation signal was specific to the SEN in the sample, and the current value was proportional to its concentration. The selectivity of our assay was also tested in the presence of other similar PAs such as intermedine, lycopsamine, and heliotrine. The detection limit is calculated by developed assay and found to be 5.45 µg/mL, which is an acceptable concentration value of SEN occurring at toxic levels for consumers. As an application of the developed sensor in food products, the electrochemical detection of SEN was successfully performed in flour and herbal tea products

Amperometric immunosensor developed for sensitive detection of SARS-CoV-2 spike S1 protein in combined with portable device

In this present study, an amperometric immunosensor was developed based on disposable screen-printed carbon electrode (SPCE) for specific and sensitive detection of SARS-CoV-2 S1 protein. Anti-SARS-CoV-2 S1 monoclonal antibody was firstly immobilized onto the electrode surface. Then, the sandwich complex was formed by addition of S1 protein, secondary antibody and HRP-IgG, respectively. Chronoamperometry measurements were done in the presence of TMB mediator and the detection of SARS-CoV-2 S1 protein was performed by using 10 mu L sample. The limit of detection (LOD) was found to be 0.19 ng/mL (equals to 24.7 amol in 10 mu L sample) in the linear range of 0.5-10 ng/mL obtained in buffer medium. The applicability of this assay was investigated in the linear range of 0.5-3 ng/mL S1 protein in artificial saliva medium with the LOD as 0.13 ng/mL (equals to 16.9 amol in 10 mu L sample). The selectivity study was examined in the presence of Hemagglutinin antigen (HA) in both mediums; buffer and artificial saliva while resulting with the successful discrimination between S1 protein and HA. The one of ultimate goals of our study is to present the possible implementation of this assay to point of care (POC) analysis. Under this aim, this assay was performed in combination with a portable device that is the commercial electrochemical analyzer. Amperometric detection of S1 protein in the range of 0.5-5 ng/mL was also successfully performed in artificial saliva medium with a resulting LOD as 0.15 ng/mL (equals to 19.5 amol in 10 mu L sample). In addition, a selectivity study was similarly carried out by portable device.Turkish Scientific and Technological Research Council (TUEBITAK, Turkey)A.E acknowledges the financial support from Turkish Scientific and Technological Research Council (TUEBITAK, Turkey) (Project No. 120S419) as the Project Investigator, and she also would like to express her gratitude to the Turkish Academy of Sciences (TUEBA, Turkey) as an Principal member for its partial support. H.S, E.Y and M.M acknowledge project scholarship by TUEBITAK (Project No. 120S419) . The authors acknowledge BioRender.com for aid in creating partially some graphical elements in graphical abstract, Figs. 1 and 2

Detection of Senecionine in Dietary Sources by Single-Use Electrochemical Sensor

Pyrrolizidine alkaloids (PAs) are produced by plants as secondary compounds that are the most widely distributed natural toxins. There have been many cases of human toxicity caused by consumption of toxic plant species, as herbal teas and grain or grain products contaminated with PA-containing seeds have been reported. Companies that produce dried spices and tea leaves should examine the PA level in their products. For the first time in the literature, a simple and inexpensive electrochemical assay based on a single-use sensor was introduced for quantitative determination of senecionine (SEN) in the most frequently contaminated food sources. SEN was immobilized on a pencil graphite electrode surface by the passive adsorption technique. Differential pulse voltammetry (DPV) was used to evaluate the oxidation signal of SEN, which was observed to be around +0.95 V. The oxidation signal was specific to the SEN in the sample, and the current value was proportional to its concentration. The selectivity of our assay was also tested in the presence of other similar PAs such as intermedine, lycopsamine, and heliotrine. The detection limit is calculated by developed assay and found to be 5.45 mu g/mL, which is an acceptable concentration value of SEN occurring at toxic levels for consumers. As an application of the developed sensor in food products, the electrochemical detection of SEN was successfully performed in flour and herbal tea products

Impedimetric Detection Based on Label-Free Immunoassay Developed for Targeting Spike S1 Protein of SARS-CoV-2

After the COVID-19 pandemic started all over the world, great importance was placed on the development of sensitive and selective bioanalytical assays for the rapid detection of the highly pathogenic SARS-CoV-2 virus causing COVID-19 disease. In this present work, an impedimetric immunosensor was developed and applied for rapid, reliable, sensitive and selective detection of the SARS-CoV-2 S1 protein. To detect the SARS-CoV-2 virus, targeting of the spike S1 protein was achieved herein by using S1 protein-specific capture antibody (Cab-S1) immobilized screen-printed electrode (SPE) in combination with the electrochemical impedance spectroscopy (EIS) technique. With the impedimetric immunosensor, the detection limit for S1 protein in buffer medium was found to be 0.23 ng/mL (equal to 23.92 amol in 8 mu L sample) in the linear concentration range of S1 protein from 0.5 to 10 ng/mL. In the artificial saliva medium, it was found to be 0.09 ng/mL (equals to 9.36 amol in 8 mu L sample) in the linear concentration range of S1 protein between 0.1 and 1 ng/mL. The selectivity of the impedimetric immunosensor toward S1 protein was tested against influenza hemagglutinin antigen (HA) in the buffer medium as well as in artificial saliva.Scientific and Technological Research Council of Turkey [120S419]This research was funded by Scientific and Technological Research Council of Turkey grant number TUB.ITAK Project No. 120S419

Impedimetric aptasensor for lysozyme detection based on carbon nanofibres enriched screen-printed electrodes

In this study, lysozyme (LYS) detection was realized by impedimetric aptasensor that consist of aptamer immobilized carbon nanofibres modified screen printed electrodes (CNF-SPEs). Under this aim, NH(2-)functionalized LYS-specific aptamer was immobilized to surface of CNF-SPEs via passive adsorption. The step-by-step fabrication process of the aptasensor and the detection of LYS was performed. During the aptasensor fabrication primarily electrochemical characterization was done via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Aptamer-LYS complex formation caused prevention of electron transfer reaction on the interface and thus charge transfer resistance (R-ct) increased. Based on this phenomenon, LYS could be quantitatively detected in accordance with the change at R-ct values obtained by EIS in the presence of [Fe(CN)(6)](3-/4-) while increasing LYS concentration. Under optimum conditions, the detection limit of the aptasensor was found to be 0.36 mu g/mL. The proposed aptasensor was also used for the determination of LYS in fetal bovine serum samples with a detection limit of 1.89 mu g/mL. Our assay in combination with the eight-channel array of electrodes was also used for LYS detection to present its implementation to nucleic acid-based array system.(c) 2021 Elsevier Ltd. All rights reserved.A.E. would like to express her gratitude to the Turkish Academy of Sciences (TUBA) as a Principal member for its partial support.Turkish Academy of Sciences (TUBA

Preparation and characterization gallic acid-titanium dioxide nanocomposites for biosensing application on voltammetric detection of DNA

The preparation and testing of Chitosan-[Gallic Acid-Titanium Dioxide] (CHIT-[GA-TiO2]) modified single-use electrodes was performed herein. TiO2 nanopArticles were firstly synthesized by alkoxide hydrolysis and solvothermal method. [GA-TiO2] samples were prepared by using gallic acid and TiO2 nanopArticles while being dissolved in chitosan solution. Crystalline structure and surface properties of the obtained Chitosan[Gallic Acid-Titanium Dioxide] (CHIT-[GA-TiO2]) nanocomposite were characterized by using X-ray diffraction analysis and scanning electron microscopy (SEM). The CHIT-[GA-TiO2] modified single-use electrodes were developed for the first time in our present study and applied for electrochemical monitoring of nucleic acid interaction. For this purpose, the modification of nanocomposite was examined using pencil graphite electrodes (PGEs) in combination with differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. After fsDNA was immobilized onto the surface of CHIT[GA-TiO2]/PGE, fsDNA concentration and immobilization time were optimized as 30 mu g/mL and 15 min, respectively. The detection limit was calculated and found to be 0.95 mu g/mL in the linear concentration range of fsDNA from 2 to 10 mu g/mL with the sensitivity of 1.161 mu A mL cm-2 mu g-1.A.E. would like to express her gratitude to the Turkish Academy of Sciences (TUBA) as a Principal member for its partial support. A.S. thanks to the Scientific and Technological Research Council of Turkey (TUBITAK) for its financial support to synthesize of TiOINF>2/INF> nanopArticles under the project grant TUBITAK-113Z635.Turkish Academy of Sciences (TUBA); Scientific and Technological Research Council of Turkey (TUBITAK) [TUBITAK-113Z635

Adsorption of Phenol from Aqueous Solution on a Low-Cost Activated Carbon Produced from Tea Industry Waste: Equilibrium, Kinetic, and Thermodynamic Study

The ability of activated carbon which was produced by chemical activation using zinc chloride from tea industry wastes (TIWAC) to adsorb phenol molecules from aqueous solution was tested by equilibrium, kinetic, and thermodynamic parameters. Phenol adsorption on TIWAC took place with a high yield at pH values in the range 4 to 8. The optimum contact period was observed as 4.0 h and from the adsorption graphs plotted as a function of time; it was established that phenol adsorption on TIWAC conformed more to a pseudosecond-order kinetic model. Additionally, it was determined that the adsorption rate is controlled by intraparticle diffusion as well as film diffusion. It was established that phenol adsorption on TIWAC can be better defined by the Langmuir adsorption model and its adsorption capacity was 142.9 mg.g(-1) from the linear Langmuir equation. Temperature had an adverse effect on adsorption yield, and hence, the adsorption process was exothermic in our case. Moreover, increasing electrolyte concentration in the medium has a positive effect on adsorption yield. From the data obtained, it was concluded that the removal of phenol from aqueous solution by TIWAC produced from tea industry wastes with a very low cost took place with an extremely high performance