scholarly journals All-Solid-State Calcium Sensors Modified with Polypyrrol (PPY) and Graphene Oxide (GO) as Solid-Contact Ion-to-Electron Transducers

Chemosensors ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 93 ◽  
Author(s):  
Hisham S. M. Abd-Rabboh ◽  
Ayman H. Kamel ◽  
Abd El-Galil E. Amr

Reliable, cost-effective, and robust screen-printed sensors were constructed and presented for Ca2+ ions determination. The sensors were based on the use of bilirubin (1,3,6,7-tetramethyl-4,5- dicarboxyethy-2,8-divinyl-(b-13)-dihydrobilenone) as a recognition sensory material in plasticized poly (vinyl chloride) (PVC) membranes. Polypyrrol (PPY) and graphene oxide (GO) were used as ion-to-electron transducers, where the effects of anionic excluder, pH, and selectivity were investigated. In a 50 mM tris buffer solution of pH 5, the electrodes offered a potential response for Ca2+ ions with a near-Nernstian slopes of 38.1 ± 0.4 (r2 = 0.996) and 31.1 ± 0.6 (r2 = 0.999), detection limits 3.8 × 10−6 (0.152 μg/mL) and 2.3 × 10−7 M (8.0 ng/mL), and linear concentration ranges of 7.0 × 10−6–1.0 × 10−2 (400–0.28 μg/mL) and 7.0 × 10−7–1.0 × 10−2 M (400–0.028 μg/mL) for sensors based on PPY and GO, respectively. Both sensors revealed stable potentiometric responses with excellent reproducibility and enhanced selectivity over a number of most common metal ions, such as Na+, K+, Li+, NH4+, Fe2+, Mg2+, and Ba2+. Impedance spectroscopy and chronopotentiometric techniques were used for evaluating the potential drift and the interfacial sensor capacitance. The proposed sensors offered the advantages of simple design, ability of miniaturization, good potential stability, and cost-effectiveness. The developed electrodes were applied successfully to Ca2+ ion assessment in different pharmaceutical products, baby-food formulations, and human blood samples. The results obtained were compared with data obtained by atomic absorption spectrometry (AAS).

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 85
Author(s):  
Wassa Waiwinya ◽  
Thitirat Putnin ◽  
Dechnarong Pimalai ◽  
Wireeya Chawjiraphan ◽  
Nuankanya Sathirapongsasuti ◽  
...  

An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; their currents served as the analytical signals. The electrochemical aptasensor exhibited good performance with a base-10 logarithmic scale. The calibration curve was achieved in the range of 0.01–50 µg/mL. The limit of detection (LOD) was 8.70 ng/mL. The developed method was considered a one-drop measurement process because a fabrication step and the probe-immobilization process were not required. This simple sensor offers a cost-effective, rapid, and sensitive detection method, and could be an alternative approach for determination of GHSA levels.


RSC Advances ◽  
2021 ◽  
Vol 11 (20) ◽  
pp. 12227-12234
Author(s):  
Hisham S. M. Abd-Rabboh ◽  
Abd El-Galil E. Amr ◽  
Elsayed A. Elsayed ◽  
Ahmed Y. A. Sayed ◽  
Ayman H. Kamel

Robust, reliable and cost-effective paper-based analytical device for potentiometric pholcodine (opiate derivative drug) ion sensing has been prepared and characterized.


2021 ◽  
Vol 324 ◽  
pp. 87-93
Author(s):  
Mohamed Adel ◽  
Abdel Hady A. Abdel-Wahab ◽  
Ahmed Abdel-Mawgood ◽  
Ahmed Osman Egiza

Graphene oxide (GO) is an oxidized nanosheets of graphite with a 2D planar structure. GO could be readily complexed with bio-entities as it possesses many oxygen-containing functionalities on its surface. The preparation process is fast, easy, and cost-effective. It was prepared using modified Hummers’ method in acidic solution as a primary solvent and potassium permanganate as an oxidizing agent. Afterwards, it was successfully characterized by FTIR, UV-visible spectroscopy, as well as XRD and Raman spectroscopy, and finally, SEM analysis. It was observed that the formed GO is mainly composed of carbon and oxygen elements rich in oxygen functional groups. Furthermore, the existence of (001) plane in XRD interprets the complete oxidation of graphite with d-spacing 9 Å. Moreover, Raman spectroscopy displayed the sp3 carbon hybridization, besides, the ID/IG ratio is found to be 0.84, which confirms the disorder between graphene oxide layers. The SEM images also pointed out that graphene oxide sheets were regularly stacked together as flake-like structures. Accordingly, the richness of oxygen-containing functionalities was confirmed. Hence, it is appropriate to be used as a base transducer for biosensing applications.


Author(s):  
Kaiming Guo ◽  
Firdoz Shaik ◽  
Jine Yang ◽  
Bin Jiang

Abstract Water splitting is considered as a potential sustainable and green technology for producing mass hydrogen and oxygen. A cost-effective self-supported stable electrocatalyst with excellent electrocatalytic performance in a wide pH range is greatly required for water splitting. This work reports on the synthesis and anchoring of Fe1CoxNiyP nanoparticles on vertically aligned reduced graphene oxide array (VrGO) via electroless plating. The catalytic activity of Fe1CoxNiyP nanoparticles is tuned finely by tailoring the cationic ratio of Co and Ni. Fe1Co2Ni1P/VrGO exhibits the lowest overpotential (58 and 110 mV) at 10 mA cm−2 and lowest tafel slope (31 and 33 mV dec−1) for hydrogen evolution reaction in 1.0 M KOH and 0.5 M H2SO4 respectively. Fe1Co1Ni2P/VrGO exhibits the lowest overpotential (173 mV) at 10 mA cm−2 with lowest tafel slope (47 mV dec-1) for oxygen evolution reaction. The enhanced performance of the electrocatalyst is attributed to improved electrical conductivity, synergistic effects and beneficial electronic states caused by the appropriate atomic ratio of Co and Ni in the bifunctional electrocatalyst. This study helps to explore the effect of variable cationic ratio in the cost-effective ternary iron group metal phosphides electrocatalysts to achieve enhanced electrocatalytic performance for water splitting in a wide pH range.


Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2655 ◽  
Author(s):  
Belal J. Muhialdin ◽  
Nazamid Saari ◽  
Anis Shobirin Meor Hussin

The challenges to fulfill the demand for a safe food supply are dramatically increasing. Mycotoxins produced by certain fungi cause great economic loss and negative impact on the sustainability of food supplies. Moreover, the occurrence of mycotoxins at high levels in foods poses a high health threat for the consumers. Biological detoxification has exhibited a high potential to detoxify foodstuffs on a cost-effective and large scale. Lactic acid bacteria showed a good potential as an alternative strategy for the elimination of mycotoxins. The current review describes the health and economic impacts associated with mycotoxin contamination in foodstuffs. Moreover, this review highlights the biological detoxification of common food mycotoxins by lactic acid bacteria.


2018 ◽  
Vol 18 (12) ◽  
pp. 8352-8359 ◽  
Author(s):  
Xibin Liu ◽  
Gaohua liao ◽  
Xiang Qi ◽  
Xiaoan Mei ◽  
Jifei Wang ◽  
...  

Hybrid fibers based on MnO2/reduced graphene oxide have been fabricated for flexible energy storage devices. Graphene oxide nanoflakes were reduced in a polytetrafluoroethylene (PTFE) pipeline under the appropriate condition to develop a fiber current collector, which also provides the possibility of weaving. The RGO fiber with the radius of about 35 μm has a resistance of 150 Ω · cm. MnO2 nanoflakes directly grow on the RGO fiber surface acting as the electrode material of the device. The MnO2/RGO hybrid fibers provide excellent energy storage performances. The as-fabricated SC exhibits a high areal capacitance of 1.37 F·cm−2 at the scan rate of 1 mV·s−1, and outstanding long-term cycling stability of 93.75% retention after 5000 cycles. This work demonstrates a cost-effective and versatile strategy for wearable energy storage devices.


2017 ◽  
Vol 82 (5) ◽  
pp. 551-565 ◽  
Author(s):  
Atefeh Nasrollahpour ◽  
Seyyed Moradi ◽  
Seyyed Moradi

A new dispersive solid phase micro-extraction (dispersive-SPME) method for separation and preconcentration of mercury(II) using ionic liquid modified magnetic reduced graphene oxide (IL-MrGO) nanoparticles, prior to the measurement by cold vapour atomic absorption spectrometry (CV-AAS) has been developed. The IL-MrGO composite was characterized by Brunauer? Emmett?Teller method (BET) for adsorption-desorption measurement, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The method is based on the sorption of mercury( II) on IL-MrGO nanoparticles due to electrostatic interaction and complex formation of ionic liquid part of IL-MrGO with mercury(II). The effect of experimental parameters for preconcentration of mercury(II), such as solution type, concentration and volume of the eluent, pH, time of the sorption and desorption, amount of the sorbent and coexisting ion concentration have been optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.08?10 ng mL-1 with a determination coefficient of 0.9995. The limit of detection (LOD) of the method at a signal to noise ratio of 3 was 0.01 ng mL-1. Intra-day and inter-day precisions were obtained equal to 3.4 and 4.5 %, respectively. The dispersive solid phase micro-extraction of mercury(II) on IL-MrGO nanoparticles coupled with cold vapour atomic absorption spectrometry was successfully used for extraction and determination of mercury(II) in water and vegetable samples.


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