Prussian Blue Analogues: A Versatile Framework for Solid-Contact Ion-Selective Electrodes with Tunable Potentials

Solid-contact ion-selective electrodes with carbazole-derived ionophores were prepared. They were characterized as acetate sensors, but can be used to determine a number of carboxylates. The potentiometric response characteristics (slope, detection limit, selectivity, and pH sensitivity) of sensors prepared with different membrane compositions (ionophore, ionophore concentration, anion exchanger concentration, and plasticizer) were evaluated. The results show that for the macrocyclic ionophores, a larger cavity provided better selectivity. The sensors exhibited modest selectivity for acetate but good selectivity for benzoate. The carbazole-derived ionophores effectively decreased the interference from lipophilic anions, such as bromide, nitrate, iodide, and thiocyanate. The selectivity, detection limit, and linear range were improved by choosing a suitable plasticizer and by reducing the ionophore and anion exchanger concentrations. The influence of the electrode body’s material upon the composition of the plasticized poly(vinyl chloride) membrane, and thus also upon the sensor characteristics, was also studied. The choice of materials for the electrode body significantly affected the characteristics of the sensors.

Download Full-text

Calibration-Free Potentiometric Sensing With Solid-Contact Ion-Selective Electrodes

TrAC Trends in Analytical Chemistry ◽

10.1016/j.trac.2021.116277 ◽

2021 ◽

pp. 116277

Author(s):

Celeste R. Rousseau ◽

Philippe Bühlmann

Keyword(s):

Ion Selective Electrodes ◽

Solid Contact ◽

Calibration Free

Download Full-text

Ion-to-electron capacitance of single-walled carbon nanotube layers before and after ion-selective membrane deposition

Microchimica Acta ◽

10.1007/s00604-021-04805-1 ◽

2021 ◽

Vol 188 (5) ◽

Author(s):

Elena Zdrachek ◽

Eric Bakker

Keyword(s):

Carbon Nanotube ◽

Ion Selective Electrodes ◽

Solid Contact ◽

Single Walled Carbon Nanotube ◽

Single Walled Carbon ◽

Essential Step ◽

Before And After ◽

Selective Membrane ◽

High Potential Stability ◽

Potential Stability

AbstractThe capacitance of the ion-to-electron transducer layer helps to maintain a high potential stability of solid-contact ion-selective electrodes (SC-ISEs), and its estimation is therefore an essential step of SC-ISE characterization. The established chronopotentiometric protocol used to evaluate the capacitance of the single-walled carbon nanotube transducer layer was revised in order to obtain more reliable and better reproducible values and also to allow capacitance to be measured before membrane deposition for electrode manufacturing quality control purposes. The capacitance values measured with the revised method increased linearly with the number of deposited carbon nanotube–based transducer layers and were also found to correlate linearly before and after ion-selective membrane deposition, with correlation slopes close to 1 for nitrate-selective electrodes, to 0.7 and to 0.5 for potassium- and calcium-selective electrodes. Graphical abstract

Download Full-text

“Green” Prussian Blue Analogues as Peroxidase Mimetics for Amperometric Sensing and Biosensing

Biosensors ◽

10.3390/bios11060193 ◽

2021 ◽

Vol 11 (6) ◽

pp. 193

Author(s):

Galina Z. Gayda ◽

Olha M. Demkiv ◽

Yanna Gurianov ◽

Roman Ya. Serkiz ◽

Halyna M. Klepach ◽

...

Keyword(s):

Prussian Blue ◽

Noble Metals ◽

High Sensitivity ◽

Graphite Electrodes ◽

Flavocytochrome B2 ◽

Prussian Blue Analogues ◽

Scientific Investigations ◽

Electrochemically Active ◽

Amperometric Sensing ◽

Prussian Blue Analogs

Prussian blue analogs (PBAs) are well-known artificial enzymes with peroxidase (PO)-like activity. PBAs have a high potential for applications in scientific investigations, industry, ecology and medicine. Being stable and both catalytically and electrochemically active, PBAs are promising in the construction of biosensors and biofuel cells. The “green” synthesis of PO-like PBAs using oxido-reductase flavocytochrome b2 is described in this study. When immobilized on graphite electrodes (GEs), the obtained green-synthesized PBAs or hexacyanoferrates (gHCFs) of transition and noble metals produced amperometric signals in response to H2O2. HCFs of copper, iron, palladium and other metals were synthesized and characterized by structure, size, catalytic properties and electro-mediator activities. The gCuHCF, as the most effective PO mimetic with a flower-like micro/nano superstructure, was used as an H2O2-sensitive platform for the development of a glucose oxidase (GO)-based biosensor. The GO/gCuHCF/GE biosensor exhibited high sensitivity (710 A M−1m−2), a broad linear range and good selectivity when tested on real samples of fruit juices. We propose that the gCuHCF and other gHCFs synthesized via enzymes may be used as artificial POs in amperometric oxidase-based (bio)sensors.

Download Full-text