Browsing by Author "Ida Tiwari"

Now showing 1 - 20 of 81

A highly efficient NiCo2O4 decorated g-C3N4 nanocomposite for screen-printed carbon electrode based electrochemical sensing and adsorptive removal of fast green dye
(Springer, 2024) Ankit Kumar Singh; Shreanshi Agrahari; Ravindra Kumar Gautam; Ida Tiwari
Herein, we demonstrate the preparation and application of NiCo2O4 decorated over a g-C3N4-based novel nanocomposite (NiCo2O4@g-C3N4). The prepared material was well characterized through several physicochemical techniques, including FT-IR, XRD, SEM, and TEM. The electrochemical characterizations via electrochemical impedance spectroscopy show the low electron transfer resistance of NiCo2O4@g-C3N4 owing to the successful incorporation of NiCo2O4 nanoparticles on the sheets of g-C3N4. NiCo2O4@g-C3N4 nanocomposite was employed in the fabrication of a screen-printed carbon electrode-based innovative electrochemical sensing platform and the adsorptive removal of a food dye, i.e., fast green FCF dye (FGD). The electrochemical oxidation of FGD at the developed NiCo2O4@g-C3N4 nanocomposite modified screen-printed carbon electrode (NiCo2O4@g-C3N4/SPCE) was observed at an oxidation potential of 0.65 V. A wide dual calibration range for electrochemical determination of FGD was successfully established at the prepared sensing platform, showing an excellent LOD of 0.13 µM and sensitivity of 0.6912 µA.µM−1.cm−2 through differential pulse voltammetry. Further, adsorbent dose, pH, contact time, and temperature were optimized to study the adsorption phenomena. The adsorption thermodynamics, isotherm, and kinetics were also investigated for efficient removal of FGD at NiCo2O4@g-C3N4-based adsorbents. The adsorption phenomenon of FGD on NiCo2O4@g-C3N4 was best fitted (R2 = 0.99) with the Langmuir and Henry model, and the corresponding value of Langmuir adsorption efficiency (qm) was 3.72 mg/g for the removal of FGD. The reaction kinetics for adsorption phenomenon were observed to be pseudo-second order. The sensitive analysis of FGD in a real sample was also studied. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.
A highly sensitive naphthaoxazole-based cell-permeable ratiometric chemodosimeter for hydrazine
(Royal Society of Chemistry, 2016) Shweta; Ajit Kumar; Neeraj; Sharad Kumar Asthana; Anand Prakash; Jagat Kumar Roy; Ida Tiwari; K.K. Upadhyay
The environmental toxicity, detonable characteristics and widespread usage of hydrazine in industrial activities, coupled with the fact that it is a leading candidate as a hydrogen reservoir, mean that selective methods for the detection of trace levels of hydrazine are much needed. We report herein a ratiometric chemodosimeter (P1) for the highly efficient detection of hydrazine at a lowest level of 1.79 × 10-9 M. The P1 probe was designed by the judicious anchoring of a naphthaoxazole skeleton to malononitrile. The same chemodosimeter also enables the bioimaging of hydrazine in live cells. The performance of P1 was tested in the form of test paper strips, as well as in the solid state for the identification of hydrazine vapours. The sensing mechanism was established through spectroscopic techniques and was further fortified through theoretical calculations using density functional theory. © 2016 The Royal Society of Chemistry.
A nanocomposite of ferrocenoyl glutaric acid hydrazone and multiwalled carbon nanotubes as a sensor for azide ions
(Royal Society of Chemistry, 2016) Ida Tiwari; Mandakini Gupta; Abhishek Rai; Lallan Mishra
A nanocomposite containing ferrocenoyl glutaric acid hydrazone and multiwalled carbon nanotubes (MWCNTs) has been synthesized and characterized for its structural, morphological and electrochemical properties. Characterization has been done using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), infrared (IR), X-ray photoelectron spectroscopy (XPS), and UV-visible studies. The electrochemical behavior and stability of the modified electrode have been investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A self-standing film of this electroactive and homogeneous composite has been obtained by solution casting method. It is observed that the ferrocenoyl glutaric acid hydrazone (L)/MWCNTs/Nafion composite has better electrochemistry, electrical properties and firm adhesion of the material at the electrode surface. The modified electrode showed an electro-catalytic response to the oxidation of azide ions at the potential of 0.30 V in 0.1 M phosphate buffer solution (pH 7.1). The linear range and detection limit for the azide ion were found to be 0.02 mM to 20 mM and 0.312 μM, respectively. © The Royal Society of Chemistry 2016.
A novel amperometric hydrogen peroxide biosensor based on horseradish peroxidase incorporated in organically modified sol-gel glass matrix/graphite paste with multiwalled carbon nanotubes
(2010) Ida Tiwari; K.P. Singh; Manorma Singh; B.C. Upadhyay; V.S. Tripathi
We herein report an electrochemical hydrogen peroxide sensor based on horseradish peroxidase immobilized in organically modified sol-gel glass (ormosil) with mediator ferricyanide along with multiwalled carbon nanotubes (mwcnts). The ormosil material is converted to fine powder followed by incorporation within graphite paste electrode. The electrochemistry of redox materials encapsulated within ormosil has been studied. The requirement of mwcnts is examined. The ormosil prepared with optimum concentration of mwcnts shows better redox electrochemistry as compared to that made without mwcnts. The biosensor has been characterized by cyclic voltammetry and chroanoamperometry. The performance, stability, and reproducibility of a new peroxide biosensor are reported. © Taylor & Francis Group, LLC.
A novel ferrocene encapsulated palladium-linked ormosil-based electrocatalytic dopamine biosensor
(2001) P.C. Pandey; S. Upadhyay; Ida Tiwari; G. Singh; V.S. Tripathi
A novel finding on the development of electrocatalytic biosensor for dopamine is reported. The new electrocatalytic dopamine biosensor is developed using ferrocene encapsulated palladium (Pd)-linked organically-modified sol-gel glass (ormosil). The alkoxy precursors used for the preparation of new ormosil-based electrocatalytic biosensor are palladium-linked glycidoxypropyltrimethoxysilane and trimethoxysilane. The optimum concentrations of these precursors are added in aqueous solution of ferrocene monocarboxylic acid and HCl followed by gelation for 30 h at 25°C to form ormosil. The ferrocene encapsulated ormosil is characterized based on cyclic voltammetric measurements. The CV results shows peak separation of 57-59 mV and a linear relation between peak current and square root of scan rate suggesting well behaved reversible electrochemistry of ormosil encapsulated ferrocene. The CV results and the detection of ferrocene in working medium shows that ferrocene is not leached out of ormosil matrix. The tyrosinase is immobilized within polyvinyl alcohol over the ferrocene encapsulated new ormosil and finally mounted using nucleopore membrane. The electrocatalytic response of immobilized tyrosinase over new ormosil is observed and the results are reported. The performance, stability, and reproducibility of new ormosil-based dopamine biosensor are reported. © 2001 Elsevier Science B.V.
A novel ferrocene-encapsulated palladium-linked ormosil-based electrocatalytic biosensor. The role of the reactive functional group
(Wiley-VCH Verlag, 2001) P.C. Pandey; S. Upadhyay; Ida Tiwari; Soma Sharma
A novel palladium-linked ormosil material with encapsulated ferrocene is reported along with its application in bioelectrocatalysis. The Pdglycidoxypropyltrimethoxysilane is made by mixing an aqueous solution of palladium chloride and glycidoxypropyltrimethoxysilane. The linkage of palladium with glycidoxypropyltrimethoxysilane is confirmed by UV-vis, mass and 13C spectroscopy. It is suggested that Pd is sandwiched between two molecules of glycidoxypropyltrimethoxysilane replacing oxygen. The new ormosil is made using Pd-linked silane precursor containing ferrocene monocarboxylic acid, trimethoxysilane and HC1. The formation of ormosil at two different temperatures (10 and 30°C) is also studied, with the result that the ormosil formed at 10°C does not show electrocatalysis of glucose oxidase whereas the ormosil made at 30°C is found to be an efficient bioelectrocatalyst. The cyclic voltammetry results show peak separation of 57-59 mV of encapsulated ferrocene made at 30°C and relatively large peak separation of the one made at 10°C. The performance, stability, and reproducibility of the new ormosil based glucose biosensor are discussed. Another important investigation in support of the above outcome is reported showing the self-assembly of palladium on the reactive solid state ormosil surface. The reactive ormosil is developed using a mixture of trimethoxysilane and 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane in acidic medium.
A novel ormosil based electrocatalytic biosensor for glucose/ethanol based on dehydrogenase modified electrode
(Wiley-VCH Verlag, 2001) P.C. Pandey; S. Upadhyay; Ida Tiwari; V.S. Tripathi
A novel ormosil material for designing electrocatalytic biosensors for glucose and ethanol based on dehydrogenase catalyzed reactions is reported. The electrode material is prepared using palladium-linked glycidoxypropyltrimethoxysilane, ferrocene monocarboxylic acid, trimethoxysilane and HCl. The ormosil prepared from these ingredients shows reversible electrochemistry of ormosil encapsulated ferrocene. The electrocatalytic oxidation of NADPH/NADH and subsequently novel dehydrogenase based biosensors for glucose and ethanol are developed. The results based on cyclic voltammetry and amperometry are reported. The enzyme sensors are developed based on the modification of electrode material by dehydrogenase enzymes. The modification of electrode material is made by two approaches of enzyme immobilization: immobilization of dehydrogenase within polyvinyl alcohol and sandwiching the dehydrogenase within two layers of ormosils among which the first layer being the electrode material itself and the second layer of ormosil prepared without palladium linkage precursor and ferrocene. The biosensor made by the second approach shows high stability and much better reproducibility of enzyme electrode performance. The results on glucose and alcohol sensing based on electrochemical measurements are reported.
A rapid and sensitive colorimetric discrimination and detection of cysteine, homocysteine and glutathione by phloroglucinol-functionalized silver nanoresonators with real applications
(Royal Society of Chemistry, 2023) Anurag Kumar Singh; Raksha Singh; Minu Yadav; Manish Sharma; Ida Tiwari; K.K. Upadhyay
This study describes the preparation and application of simple yet effective silver nanoprobes for the facile colorimetric discrimination and detection of cysteine, homocysteine and glutathione in real time at the micro molar levels with three distinct colors. These nanoprobes were further exploited to detect and determine cysteine and glutathione from their respective commercial samples, with recoveries exceeding 80%. FT-IR spectroscopy, UV-Vis spectroscopy, SEM, TEM, EDAX, AFM and DLS studies have supported our findings. © 2023 The Royal Society of Chemistry.
A reduced graphene oxide-cyclodextrin-platinum nanocomposite modified screen printed electrode for the detection of cysteine
(Elsevier B.V., 2018) Monali Singh; Nandita Jaiswal; Ida Tiwari; Christopher W. Foster; Craig E. Banks
This article presents a highly sensitive and specific new sensing platform for cysteine determination. For the fabrication of electrochemical sensor, reduced graphene oxide-β-cyclodextrin-platinum nanocomposite (GR/CD/Pt) was prepared and surface of screen-printed electrodes were bulk modified with this nanocomposite which exhibited excellent electrocatalytic activity towards the sensing of cysteine. The GR/CD/Pt was characterized using SEM, TEM, AFM, FT-IR, TGA. The electrochemical behaviour of the fabricated sensor was investigated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. During the determination of cysteine, a good electrocatalytic response current was obtained which is linear with respect to the concentration of cysteine over the range 0.5–170 μM with the limit of detection corresponding to 0.12 μM. © 2018 Elsevier B.V.
A selective hydrolytic and restructuring approach through a Schiff base design on a coumarin platform for “turn-on” fluorogenic sensing of Zn 2+
(Royal Society of Chemistry, 2019) Abha Pandey; Sharad Kumar Asthana; Anand Prakash; Jagat Kumar Roy; Ida Tiwari; K.K. Upadhyay
A new Schiff base, CMD, designed based on a coumarin platform was synthesized and fully characterized through single crystal X-ray diffraction studies. CMD underwent selective Zn 2+ -triggered hydrolysis in ethanolic medium followed by restructuring of its fragments, resulting in a “turn-on” green fluorogenic response. This response was confirmed through various physico-chemical measurements along with single crystal X-ray diffraction studies. This selective hydrolytic fluorogenic event was exploited for the successful optical detection and live cell imaging of Zn 2+ in SiHa cells. The above restructured products were characterized as two new Schiff bases, viz.CM and NSA, of which NSA was highly fluorescent (green). Hence, the formation of this green fluorogenic product accounted for the above fluorogenic “turn-on” sensing of Zn 2+ with a sub-nanomolar detection limit. Spectroscopic evidence along with mass determinations indicated that the Zn-CMD ensemble took the form of CM-Zn-CM in solution, supporting our above proposal of hydrolysis and restructuring. However, the X-ray diffraction studies of the Zn-CMD ensemble further revealed it to consist of NSA and CM-Zn-CM′, where CM′ is yet another new Schiff base formed in situ during the process of developing single crystals. © The Royal Society of Chemistry.
Acetylthiocholine/acetylcholine and thiocholine/choline electrochemical biosensors/sensors based on an organically modified sol-gel glass enzyme reactor and graphite paste electrode
(Elsevier Sequoia SA, 2000) P.C. Pandey; S. Upadhyay; H.C. Pathak; C.M.D. Pandey; Ida Tiwari
Electrochemical sensors for acetylthiocholine and acetylcholine are described. The non-mediated electrochemistry of acetylthiocholine and thiocholine is studied on the surface of graphite paste electrode and results show that acetylthiocholine is directly oxidized/reduced at >0.32 V vs. Ag/AgCl in both acidic and basic medium. In basic medium, both cathodic and anodic peak currents are less as compared to that of the same amount in acidic medium, which shows that the kinetics of non-enzymatic hydrolysis of acetylcholine into electroactive thiocholine is faster in acidic medium and slower in basic medium. Thiocholine is directly oxidized/reduced at >0.35 V vs. Ag/AgCl with relatively larger anodic current compared to cathodic peak current similar to that of acetylcholine results recorded in acidic medium (pH 6.0). The electrochemical sensor/biosensors for acetylthiocholine/acetylcholine and thiocholine/choline are developed using two enzyme reactors: (1) acetylcholinesterase (AChE) encapsulated organically modified sol-gel glass, and (2) choline oxidase (ChO) immobilized within mediators (tetracyanoquinodimethane (TCNQ), tetrathiafulvalene (TTF), and dimethyl ferrocene (dmFc))-modified graphite paste electrodes. The AChE-immobilized into organically modified sol-gel glass behaves as the reactor for enzymatic hydrolysis of acetylthiocholine/acetylcholine into thiocholine/choline, whereas mediator- and ChO-modified paste electrodes are used for the detection of thiocholine/choline through mediated mechanism. The electrochemistry of AChE-generated thiocholine is studied at the mediator-modified electrodes in the presence and absence of ChO. It is observed that thiocholine undergoes both mediated and non-mediated oxidation in the absence of ChO as well as oxidation through enzyme-catalyzed mediated reactions. The results based on cyclic voltammetry on the oxidation of thiocholine at the surface of mediator-modified electrodes in the presence and absence of ChO are reported. In the presence of the ChO large anodic current is observed near the mediator's redox potentials as compared to the anodic current in the absence of enzyme, which shows mediated bioelectrochemistry of thiocholine. The typical response curves for the detection of thiocholine/choline using mediators and ChO-modified electrodes below 0.24 V vs. Ag/AgCl in 0.1 M Tris-HCl buffer pH 8.0 are reported. Comparative analytical performance on the mediated electrochemical responses of the biosensors is discussed.
Advances in Sensors' Nanotechnology
(Wiley Blackwell, 2014) Ida Tiwari; Manorama Singh
Nowadays, sensors are considered as important instruments available particularly in health care systems, for diagnosis and monitoring of diseases as there has been a strong demand for producing highly sensitive, responsive, selective, and cost-effective sensors. As a result, research emphasis is on developing new sensing materials and technologies to amplify signal of biorecognition event. In this context, the use of nanomaterials for the construction of sensor devices constitutes one of the most exciting approaches. The extremely promising prospects of these devices accrue from the unique properties of nanomaterials. Although different nanomaterials (e.g., carbon nanotubes, nanoparticles, graphene, etc.) are employed for the construction of sensors in different fields, it is in medical diagnostics where maximum application can be made due to enhanced analytical performance with respect to other designs. With the advent of nanotechnology, research is on track to create highly selective, highly sensitive and miniaturized sensors for medical applications. Miniaturized sensors can lead to lower power consumption, reduced weight, and low cost. © 2014 Scrivener Publishing LLC. All rights reserved.
An amperometric sensor for nanomolar detection of hydrogen peroxide based on encapsulation of horseradish peroxidase in thymol blue-ormosil composite
(2011) Ida Tiwari; Manorama Singh; V.S. Tripathi; G. Lakshminarayana; Masayuki Nogami
An amperometric biosensor based on horseradish peroxidase and thymol blue-organically modified sol-gel glass composite has been fabricated for the determination of H 2O 2. We are for the first time reporting electrochemistry of thymol blue encapsulated within organically modified sol-gel glass. The biosensor has been characterized by electrochemical and amperometric measurements. The biosensor shows fast response with minimum interference. Under the optimized experimental conditions, H 2O 2 could be determined in a linear calibration range from 1.0×10 -8 M to 1.2×10 -3 M with a correlation coefficient of 0.998, sensitivity of 23.74 μA/mM and a detection limit of 1 nM at S/N ratio = 3. Copyright © 2011 American Scientific Publishers All rights reserved.
An anthraquinone moiety/cysteamine functionalized-gold nanoparticle/chitosan based nanostructured composite for the electroanalytical detection of dissolved oxygen within aqueous media
(Royal Society of Chemistry, 2014) Ida Tiwari; Mandakini Gupta; Rajiv Prakash; Craig E. Banks
This work reports a nanostructured composite electrode comprising gold nanoparticles, anthraquinone derivatives and chitosan electrically wired via immobilisation upon a glassy carbon macroelectrode. The as-prepared nanostructured composite was morphologically characterised using transmission electron microscopy with surface characterization performed with atomic force microscopy while other physical characterization was undertaken by infra-red, UV-Vis, and energy dispersive X-ray spectroscopy. Electrochemical investigations and stability measurements of the composite electrode were performed by cyclic voltammetry. Electrocatalytic activity of the composite electrode was investigated for the oxygen reduction reaction in 0.1 M phosphate buffer solution of pH 6.5. Furthermore, the response characteristics show that this fabricated electrode has a shelf-life of between 3 and 4 months and has improved electrochemical and electrical properties and firm adhesion of the material with homogeneous dispersion at the electrode surface. The linear range and detection limit for the electrochemical detection of dissolved oxygen under the optimum conditions using the nanostructured composite was found to be over the accessible range of 0.2 to 5.8 mg L-1 and 0.03 mg L-1 respectively. This journal is © the Partner Organisations 2014.
An Array-based Photolithographically Patterned Electrochemical Sensing Platform for Highly Sensitive Determination of Uric Acid, Dopamine, l-Tryptophan, and Pyridoxine in Biological Samples
(Springer Nature, 2024) Ankit Kumar Singh; Shreanshi Agrahari; Shivani Shukla; Ida Tiwari; Muhammad Ahmad; S. Ravi P. Silva
Biomolecules play important roles in physiological functions and pharmacological characteristics of human body. Uric acid (UA) is the end product of purine. Dopamine (DA) is a neurotransmitter of catecholamine group. l-tryptophan is an essential amino acid that can be metabolized to neuroactive substances. Pyridoxine is a water-soluble vitamin playing an important role in nervous system. The abnormalities in their concentration levels led to a wide range of significant mental and physical illnesses. Thus, electrochemical analysis of these analytes on an array system would be beneficial from clinical or scientific points of view. This work was aimed at the development of practical sensor array for determination of multiple analytes on a single sensing platform using individually addressable microelectrodes. The occurrence of adsorption–desorption phenomenon on the surface of palladium microelectrode array (Pd MEA) printed on the silicon wafer through photolithography was exploited for electro-oxidation of UA, DA, l-tryptophan and pyridoxine. The sensing of electroactive UA was done using carbon nanotubes(CNTs) grown Pd MEA as a working electrode, while selectivity for other analytes was achieved by the modification of CNTs/Pd MEA through electrodeposition of poly(l-lysine) (poly(l-lysine)/CNTs/Pd MEA) for DA sensing, poly(l-arginine) (poly(l-arginine)/CNTs/Pd MEA) for l-tryptophan sensing and reduced graphene oxide (rGO/CNTs/Pd MEA) for pyridoxine sensing. The electrochemical differential pulse voltammetry (DPV) analyses reveal excellent linearity in the concentration ranges of 50–6000 µmol/L, 2–8000 µmol/L, 20–15,000 µmol/L, and 10–5000 µmol/L with detection limits of 15.0, 0.5, 10.0, and 1.0 µmol/L for UA, DA, l-tryptophan, and pyridoxine, respectively. The proposed multiple analytes sensor has shown very high sensitivities of 140, 9580, 2280, and 940 µA·(µmol·L−1)−1·cm−2 for UA, DA, l-tryptophan, and pyridoxine sensing, respectively. Further, accuracy and reliability of the fabricated sensor were also tested in real samples. © The Nonferrous Metals Society of China 2024.
An impedimetric biosensor based on electrophoretically assembled ZnO nanorods and carboxylated graphene nanoflakes on an indium tin oxide electrode for detection of the DNA of Escherichia coli O157:H7
(Springer, 2020) Nandita Jaiswal; Chandra Mouli Pandey; Shipra Solanki; Ida Tiwari; Bansi Dhar Malhotra
Aminopropyltrimethoxysilane (APTMS)-functionalized zinc oxide (ZnO) nanorods and carboxylated graphene nanoflakes (c-GNF) were used in a composite that was electrophoretically deposited on an indium tin oxide (ITO) coated glass substrate. The modified ITO electrodes were characterized using various microscopic and spectroscopic techniques which confirm the deposition of the APTMS-ZnO/c-GNF composite. The electrodes have been used for the covalent immobilization of an Escherichia coli O157:H7 (E. coli)-specific DNA prob. Impedimetric studies revealed that the gene sensor displays linear response in a wide range of target DNA concentration (10−16 M to 10−6 M) with a detection limit of 0.1 fM. The studies on the cross-reactivity to other water-borne pathogens show that the bioelectrode is highly specific. [Figure not available: see fulltext.] © 2019, Springer-Verlag GmbH Austria, part of Springer Nature.
An insight review on the application of polymer-carbon nanotubes based composite material in sensor technology
(2009) Ida Tiwari; K.P. Singh; Manorama Singh
Carbon nanotubes (CNT) polymer composites have shown potential applications for sensor/ biosensor fabrication. Methods for preparation, characteristics are highlighted and future aspects are explored. Various analytes and polymeric materials have been cited to prove the importance of polymer/CNT composite systems in sensor technology. © Pleiades Publishing, Ltd., 2009.
An organically modified silicate-based ethanol biosensor
(Academic Press Inc., 2001) P.C. Pandey; S. Upadhyay; Ida Tiwari; V.S. Tripathi
A novel electrocatalytic ethanol biosensor using ferrocene-encapsulated palladium (Pd)-linked organically modified sol-gel glass (ormosil) is reported. The alkoxy precursors used to prepare the new ormosil-based electrocatalytic biosensor are Pd-linked glycidoxypropyltrimethoxysilane and trimethoxysilane. Pd-glycidoxypropyltrimethoxysilane (black solution) is made by mixing aqueous solutions of palladium chloride and glycidoxypropyltrimethoxysilane. The new ormosil is made using a Pd-linked silane precursor, trimethoxysilane, an aqueous solution of ferrocene monocarboxylic acid, and HCl. Alcohol dehydrogenase (ADH) is assembled over the ferrocene-ormosil layer using polyvinyl alcohol and then protecting the immobilized enzyme layer using Millipore filter membranes (pore size 1 μm). The electrocatalytic response of immobilized ADH, soluble nicotinamide adenine dinucleotide, and Pd-linked ormosil-encapsulated ferrocene is then observed. The electrocatalytic oxidation of NADH and the subsequent ADH-catalyzed formation of NADH are monitored electrochemically. Typical results recorded after the addition of varying concentrations of ethanol are reported; however, the sensor is sensitive to other alcohol and known ADHsensitive substrates. The stability and reproducibility of the new ethanol biosensor are reported. © 2001 Academic Press.
Anhydrous proton-conducting organic-inorganic hybrid membranes synthesized from tetramethoxysilane/methyltrimethoxysilane/diisopropyl phosphite and ionic liquid
(2010) Gandham Lakshminarayana; Vijay S. Tripathi; Ida Tiwari; Masayuki Nogami
Inorganic-organic hybrid membranes were prepared by sol-gel process with tetramethoxysilane/methyltrimethoxysilane/diisopropyl phosphite and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid as precursors. The Fourier transform infrared spectroscopy (FT-IR) and 31P, 29Si, 1H, 13C, and 19F nuclear magnetic resonance measurements have shown good chemical stability and complexation of (POH[(CH3)2CHO]2) with [BMIMBF4] ionic liquid in the fabricated hybrid membranes. The influence of the textural properties of all the prepared composite membranes could be interpreted from nitrogen adsorption-desorption measurements. The average pore size was increased proportionally with the ionic liquid weight percent ratio in the host phosphosilicate matrix from 2.59 to 11.71 nm, respectively. Thermogravimetric analysis and differential thermal analysis measurements confirmed that the hybrid membranes were thermally stable up to 260 °C. Thermal stability of the hybrid membranes was significantly enhanced by the presence of inorganic SiO2 framework and high stability of [BF4] anion. For all the composite membranes, the conductivities were measured within the temperature range (-30 °C) to 150 °C, and a maximum conductivity of 7 × 10-3 S/cm at 150 °C was achieved for 40 wt.% ionic liquid-based composite membrane under nonhumidified conditions. © 2010 Springer-Verlag.
Answer to comments on: ‘Voltammetric analysis of epinephrine using glassy carbon electrode modified with nanocomposite prepared from Co-Nd bimetallic nanoparticles, alumina nanoparticles and functionalized multiwalled carbon nanotubes’ by Ida Tiwari et al., (Doi: 10.1007/s11356-022–23660-y)
(Springer Science and Business Media Deutschland GmbH, 2023) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
This is an answer to the letter by the editor that was sent in response to our previously published article entitled “Voltammetric analysis of epinephrine using glassy carbon electrode modified with nanocomposite prepared from Co-Nd bimetallic nanoparticles, alumina nanoparticles and functionalized multiwalled carbon nanotubes." We are grateful to the writers for showing an interest in our manuscript and for providing such helpful feedback. We emphasise that our research was just a preliminary investigation to detect epinephrine in different biological samples, however, in literature a link between epinephrine and acute respiratory distress syndrome (ARDS) is already reported. Hence, we are agreeing to the authors that epinephrine is suggested as a cause for ARDS following anaphylaxis. It is recommended that more research be carried out to evaluate the possibility of epinephrine as a cause for ARDS and to validate the therapeutic relevance of the findings. Additionally, the purpose of our research was electrochemical sensing of epinephrine alternative to the conventional means like HPLC, fluorimetry, etc. for epinephrine detection. We have found that benefits which the electrochemical sensors have, are their simplicity, cost-effectiveness, ease of use owing to their small size, mass manufacture, and straightforward operation, as well as their extreme sensitivity and selectivity, hence the electrochemical sensing methods are more beneficial than conventional techniques for epinephrine analysis. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.