Determination Of Potassium Ions Research Articles

A novel red emission carbon quantum dots-based aptasensor for detection of potassium ions in vitro and in vivo and its application in plant imaging

The determination of potassium ion (K+) concentration in organisms is of particular importance. Herein, an efficient, sensitive, and eco-friendly fluorescence aptasensor for detecting potassium ions (K+) was designed based on the interaction of aptamer (K-Apt), complementary sequence of aptamer (C-Apt), red emission carbon quantum dots (R-CDs), and graphene oxide (GO). Red luminescent CDs modified with K+ aptamer(R-CDs@K-Apt) and C-Apt modified GO (C-Apt@GO) were used as the fluorescence donor and acceptor, respectively, in this aptasensor. K+ was detected sensitively using the fluorescence resonance energy transfer (FRET) method. The linear range of this aptasensor was 5.0 × 10−9–2.2 × 10−7 mol/L, and its detection limit was as low as 6.2 × 10−11 mol/L. Importantly, this aptasensor can be employed for quantitative K+ detection in serum because of the enhancement of its selectivity and biocompatibility by the modification of biomolecules including K-Apt and C-Apt. Furthermore, the aptasensor’s red emission at 625 nm enabled it to completely avoid the background fluorescence caused by chlorophyll in wheat seedlings, allowing it to display the K+ concentration of the wheat through plant imaging. These findings lay a foundation for the development of a novel detection technique for analyzing the distribution of K+ in the body fluids of animals and plants.

Newly found K+-Thioflavin T competitive binding to DNA G-quadruplexes and the development of a label-free fluorescent biosensor with extra low detection limit for K+ determination in urine samples

The determination of potassium ion K+ in body fluids is important in health monitoring and diagnoses. One of the interesting and simple methods for K+ detection is the use of label-free biosensors based on DNA G-quadruplexes (GQs) coupled with a specific fluorescent probe, such as Thioflavin T (ThT), which lights up when bound with K+-stabilized GQs. However, these biosensors are not generally sensitive. In this work, we found a solution: at a low concentration, K+ competes with ThT in binding to a bimolecular GQ or a tetramolecular GQ, resulting in a decrease in ThT fluorescence emission with increasing K+. Therefore, we developed a label-free turn-off fluorescent K+ sensor. The sensor provides a very low detection limit of 21.87 ± 0.59 nM. Other possible interfering components in urine did not exert any effect even at quantities that were 10-fold greater than their upper limit of normal concentrations found in urine samples. With its only requirement of diluting samples, the developed low-cost label-free probe and simple sensor was successfully applied to the direct detection of K+ in normal urine samples with high accuracy (recoveries ranged from 90% to 100%).

Інноваційні технології пошуків корисних копалин, основані на дослідженнях флюїдних включень у мінералах

The innovative approach to the development of prospective technologies (methods) was substantiated on crystallogenic and physicochemical principles of the knowledge of mineral forming environments (fluids) (thermobarogeochemistry – mineralofluidology – fluid inclusions) as a new branch of geological knowledge within the framework of the new scientific direction in the geology – «thermobarometry and geochemistry of gases of veinlet-impregnated mineralization in deposits of oil- and gas-bearing areas and metallogenic provinces» as a natural phenomenon of the Earth’s lithosphere. According to him, the creation of radically new technologies and realization of prospecting for mineral deposits (first of all hydrocarbons and gold) simultaneously with the elucidation of the problem of genesis and synthesis of hydrocarbons at the atomic-molecular level fixed by such defects in the mineral crystals as fluid inclusions. Developed technologies, namely: determination of genesis of hydrocarbon gases; determination of prospects of oil and gas presence of a local area; local forecast of enriched areas of gold ore fields; express determination of potassium ions in inclusions for identification of gold-enriched and barren veinlet formations, – belong to the branch of the exploration geology and geochemistry and are used to ascertain genetic guestions, to solve tasks of the mineralogical-geochemical prediction and prospecting for mineral deposits in the local structures of oil- and gas-bearing areas and metallogenic provinces. The comparison of fluid inclusions of veinlets and host rocks based on the sections of a number of wells has shown the considerable possibilities of the developed technologies and prospects of the usage of thermobarogeochemical-mineralofluidological indicators in the complex with the geochemical and geophysical (petrophysical) methods, data of geological survey, deep-seated drilling while predicting hydrocarbon deposits in the local structures of the sedimentary strata promising for oil and gas and making necessary amendments in the directions of the following geological-prospecting works.

Solid‐state ion sensor for on‐chip determination of potassium ion in body fluid

AbstractThis article describes a synthetic route for the fabrication of all‐solid‐state potentiometric ion‐sensing device for on‐chip determination of potassium ion in body fluid. The sensing electrodes comprised of (a) a solid‐state reference electrode made from a Ag/AgCl‐printed electrode covered with a solid‐electrolyte‐embedded membrane made from siloxane polymer and (b) solid‐state ion‐selective electrode as working electrode made by assembling ionophore‐impregnated PVC membrane casting solution over a ion exchanger‐impregnated membrane. The ion exchanger‐impregnated membrane is cast by assembling siloxane–polyindole nanodispersion over working electrode of screen‐printed electrode to yield constant dipolar potential. The screen‐printed electrodes comprising of all‐solid‐state reference and working electrode can be operated under zero current flow to monitor potassium ion in given sample. The configuration of the printed electrodes is designed to fix a microneedle assembly over the working portion of both reference and working electrodes for transdermal ion sensing. The functional alkoxysilanes derived from nanodispersion allow to make solid‐state reference electrode avoiding the use of internal filling solution providing innovation in designing potentiometric sensor. In one aspect, a potentiometric device for detecting analyte in biological fluid that can include a array of hollowed microneedle in which each needle acts as protruded needle structure including an exterior wall forming a hollow interior covering both solid‐state working and reference electrode with an opening at terminal end in such that one microneedle is converted into a potassium ion‐selective electrode.

Label Free Determination of Potassium Ions Using Crystal Violet and Thrombin-Binding Aptamer

A label-free method for sensitive determination of potassium ions was developed. The most commonly studied thrombin-binding aptamer was used as the molecular probe and crystal violet was chosen as a fluorescence signal reporter. The fluorescence of crystal violet was significantly enhanced when the crystal violet solution was mixed with the single-stranded thrombin-binding aptamer. However, in the presence of potassium ions, due to the formation of potassium induced G-quadruplex structures, the fluorescence decreased. Potassium ions were determined using the change in fluorescence. The conformational transformation was investigated by circular dichroism, and interferences caused by sodium ions were studied. This label-free method offers a simple procedure that induces minimum effects on the G-quadruplex formation. Under the optimized conditions, the method exhibited a linear range from 30–420 µM for potassium ions with a detection limit of 6 µM.

Effective Photocatalytic Disinfection of E. coli K-12 Using AgBr−Ag−Bi2WO6 Nanojunction System Irradiated by Visible Light: The Role of Diffusing Hydroxyl Radicals

Urgent development of effective and low-cost disinfecting technologies is needed to address the problems caused by an outbreak of harmful microorganisms. In this work, we report an effective photocatalytic disinfection of E. coli K-12 by using a AgBr-Ag-Bi(2)WO(6) nanojunction system as a catalyst under visible light (lambda >or= 400 nm) irradiation. The visible-light-driven (VLD) AgBr-Ag-Bi(2)WO(6) nanojunction could completely inactivate 5 x 10(7) cfu mL(-1) E. coli K-12 within 15 min, which was superior to other VLD photocatalysts such as Bi(2)WO(6) superstructure, Ag-Bi(2)WO(6) and AgBr-Ag-TiO(2) composite. Moreover, the photochemical mechanism of bactericidal action for the AgBr-Ag-Bi(2)WO(6) nanojunction was investigated by using different scavengers. It was found that the diffusing hydroxyl radicals generated both by the oxidative pathway and the reductive pathway play an important role in the photocatalytic disinfection. Moreover, direct contact between the AgBr-Ag-Bi(2)WO(6) nanojunction and bacterial cells was not necessary for the photocatalytic disinfection of E. coli K-12. Finally, the photocatalytic destruction of the bacterial cells was directly observed by TEM images and further confirmed by the determination of potassium ion (K(+)) leakage from the killed bacteria. This work provides a potential effective VLD photocatalyst to disinfect the bacterial cells, even to destruct the biofilm that can provide shelter and substratum for microorganisms and resist to disinfection.

Development and application of a fluorescent sensor for potassium ions based on a calix[6]arene ionophore and a novel cationic dye

A plasticised poly(vinyl chloride) optode membrane incorporated with a calix[6]arene hexaester, a H+-selective chromoionophore (3,3′,5,5′-tetramethyl-N,N-dibenzylbenzidine, a novel synthetic cationic dye) and a lipophilic potassium tetrakis(4-chlorophenyl)borate was used as a sensing device for the indirect optical determination of potassium ions. It exhibited a reversible response to the potassium ion in 0.05 mol/l HCl buffer media in the concentration range from 1 × 10− 6 to 1 × 10− 2 mol/l. The linear range was from 1.53 × 10− 5 to 3.20 × 10− 3 mol/l. The proposed optode sensor exhibited a fast response of less than 1 min, good repeatability (n = 7, RSD = 3.62%) at 5 × 10− 5 mol/l, and long-term stability with 92% of its initial sensitivity after 1 month of storage. The selectivity of the potassium-selective membrane allows its application for the detection of the potassium concentration in real sample analysis. The result was satisfactory compared with atomic absorption spectrometry.

Highly sensitive determination of trace potassium ion in serum using the resonance light scattering technique with sodium tetraphenylboron

A resonance light scattering technique has been developed in order to determine potassium ion in serum. Potassium ion was found to bind the tetraphenylboronate anion [(C6H5)4B]− in acetate buffer (pH 8.0) in the presence of sodium dodecyl benzene sulfonate as a stabilizer, forming the B(C6H5)4-K aggregate which produces intense resonance scattering light. Effects of factors such as acidity, ionic strength and interferents on the RLS of B(C6H5)4-K were investigated. The solution pH close to neutral facilitates the production of RLS, and few biologically relevant species interfere in the determination of potassium ion. The resonance scattering light intensity at the maximum peak of 567 nm was linear to the concentration of potassium ion in the range of 0.2–2.0 µg mL−1 with a detection limit of 20.0 ng mL−1. The method was applied to determine trace amounts of potassium ion in serum and showed high sensitivity and accuracy compared with the clinically used ion-selective electrode method.

Efficient destruction of bacteria with Ti(IV) and antibacterial ions in co-substituted hydroxyapatite films

Hydroxyapatite (Ca10(PO4)6(OH)2: HAP) was co-substituted with Ti(IV) and antibacterial ions (Ag+, Cu2+ or Zn2+) (HAPTiM), by coprecipitation and ion-exchange methods. Both HAPTiAg and HAPTiCu coated on porous spumous nickel film showed high efficiency for killing Escherichia coli and Staphylococcus aureus in the dark and under weak UVA irradiation, respectively. Moreover, their bactericidal activities were much higher than that of P25-TiO2 film. The studies of ESR revealed that not only O2− was formed on HAPTiM, HAPTi, HAP and P25-TiO2 films under weak UVA irradiation, but also at ambient temperature without light O2− was generated on HAPTiCu, HAPTiAg, and HAPTi. The redox couples of Cu0/Cu2+ and Ag0/Ag+ in the structure of HAPTiCu (Ag) caused the transfer of electron leading to the O2− generation under the above conditions. The higher bactericidal activities of HAPTiM were due to the synergy of the oxidation role of the O2− and the bacteriostatic action of antibacterial ions. The process of the damage of the cell wall and the cell membrane was directly observed by TEM, and further confirmed by the determination of potassium ion (K+) leakage from the killed bacteria.

Efficient Destruction of Pathogenic Bacteria with NiO/SrBi2O4 under Visible Light Irradiation

The photocatalytic inactivation of pathogenic bacteria in water was investigated systematically with NiO/SrBi2O4 under visible light (lambda > 420 nm) irradiation. The catalyst was found to be highly effective in killing Escherichia coli, a Gram-negative bacterium, and Staphylococcus aureus, a Gram-positive bacterium. ESR studies revealed that *OH and O2*- were involved as the active species in the photocatalytic reaction. The decomposition process of the cell wall and the cell membrane was directly observed byTEM and further confirmed by the determination of potassium ion (K+) leakage from the killed bacteria. A possible cell damage mechanism by visible-light-driven NiO/SrBi2O4 is proposed. In addition, the effects of pH, methanol, and inorganic ions on bacterial photocatalytic inactivation were investigated. These results indicated that the electrostatic force interaction of bacteria-catalyst is crucial for high bactericidal efficiency.

Determination of potassium ions in pharmaceutical samples by FIA using a potentiometric electrode based on ionophore nonactin occluded in EVA membrane

A simple and rapid method was developed for the K + ions determination employing a flow injection system using a flow-through electrode based on the naturally-occurring antibiotic ionophore nonactin occluded in a polymeric membrane. The nonactin ionophore was trapped in poly(ethylene- co-vinyl acetate) (EVA) matrix (40% w/w in vinyl acetate) and dispersed on the surface of a graphite-epoxy tubular electrode. The plasticizer-free all-solid-state potassium-selective electrode showed a linear response for K + concentrations between 5.0×10 −5 and 5.0×10 −2 M ( r=0.9995) with a near-Nernstian slope of 51.5 mV per decade, when Tris–HCl buffer (pH 7.0;0,1 M) was employed as a carrier. The potentiometric-FIA system allows an analytical frequency of 120 samples per hour with a precision of 3.6%. The relative standard deviations (R.S.D.) for K + determination in pharmaceuticals samples, without any previous treatment, were lower than 4.0%, comparable to those obtained by flame photometry. Ammonium is the main analytical interference and the electrode response time was 5 s at 25 °C. The useful lifetime of the tubular sensor is longer than 3 months in continuous use.

Silver Hexacyanoferrate Film Directly Modified Electrode as a Potentiometric Sensor for Potassium Ion

A chemically modified electrode (CME) was fabricated by direct modification of a silver electrode with a thin film of silver hexacyanoferrate. The modified electrode was used as a potentiometric sensor for the determination of potassium ion. The sensor exhibits a response to potassium ion in a wide concentration range from 8.0 × 10−5 to 1.0 M with a low detection limit of 4.0 × 10−5 M. The potassium-selective electrode has a relatively short response time. It has a good sensitivity with a near-Nernstian slope of 53–57 mV/decade and good selectivity in the presence of possible interferences. The electrode response is highly sensitive to some controllable parameters mainly the thickness of electroactive film which is controlled by the charge passed in the cell during the deposition of the film. Stability of the directly modified electrode and its potentiometric response were also investigated during long-term usage, which were indicative of the possibility of the potassium-selective electrode for using in a long period.

Application of an ion-selective field effect transistor with a photocured polymer membrane in nephrology for determination of potassium ions in dialysis solutions and in blood plasma

Application of a potassium ion sensor based on an ion sensitive field effect transistor (ISFET) for ion control of a dialysis solution in an artificial kidney and in blood plasma of patients treated by hemodialysis is presented. Sensors and their long-term stability were characterised in constant contact with test solutions. Test results are compared to those obtained with conventional ion-selective electrodes and commercial blood ion analyser. Tested ISFET sensors showed high reliability in potassium ion measurements in the physiologically significant concentration range which, along with low cost of their production, makes them promising for cited application.

THE SYNTHESIS OF STYRENE/4'-VINYL-BENZO-24-CROWN-8 COPOLYMER AND ITS USE IN POTASSIUM-ION SELECTIVE ELECTRODES

A synthetic procedure has been developed for the preparation of styrene/4'-vinyl-benzo-24-crown-8 copolymer (SPV-B24C8). The resulting copolymer was used as a membrane carrier to construct a K+ ion-selective electrode. The electrode exhibits a Nernstian response for K+ ions over a wide concentration range. The nature of the plasticizer, the additive, the concentration of internal solutions in the electrodes and the composition of the membrane were investigated. The performance of the electrode in terms of electrode reproducibility, response stability and regeneration was also studied. The selectivity coefficients of the electrode for potential interferents including alkali, alkaline earth, some transition and heavy metal ions were found to be in the order of 10-3 or less. The electrode was successfully used for the determination of potassium ion in blood serum.

Flow-injection determination of traces of potassium by extraction with bis[2-(5′-bromo-2′-pyridylazo)-5-( N-propyl- N-sulphopropylamino)phenolato]cobaltate(III) and cryptand[2.2.2

The determination of trace amounts of potassium ion was carried out by liquid-liquid extraction using cobalt(III) 2-(5′-bromo-2′-pyridylazo)-5-( N-propyl- N-sulphopropylamino)phenolate and cryptand[2.2.2] with a flow-injection system. The determination of potassium ion in the range from tens to several hundred μg l −1 was possible with a sampling frequency of 30 h −1. The detection limit for potassium at a signal-to-noise ratio of 3 was 4.0 × 10 −7 M (16 μg l −1). Interferences from alkaline earth and heavy metal ions could be avoided by adding dilithium EDTA to the sample and/or reagent solutions. The results obtained for botanical reference materials were in good agreement with the certified values.

Determination of Potassium Ion and Sodium Ion by the Auto-Analyzer

Determination of Potassium Ion and Sodium Ion by the Auto-Analyzer