Molecular receptors and electrochemical sensors based on functionalized calixarenes

The approaches to the design of molecular receptors based on functionalized calixarenes aimed at recogni- tion of ions and neutral organic compounds are considered; such receptors can serve as the basis for potentiometric and amperometric sensors. The application of the receptors is exemplified and analytical characteristics of the sensors are discussed. Particular attention is paid to the factors affect- ing the efficiency of recognition and selectivity and sensi- tivity of the developed sensors. The bibliography includes 173 references. © 2010 Russian Academy of Sciences and Turpion Ltd

Advances in electrochemical aptasensors based on carbon nanomaterials

Carbon nanomaterials offer unique opportunities for the assembling of electrochemical aptasensors due to their high electroconductivity, redox activity, compatibility with biochemical receptors and broad possibilities of functionalization and combination with other auxiliary reagents. In this review, the progress in the development of electrochemical aptasensors based on carbon nanomaterials in 2016–2020 is considered with particular emphasis on the role of carbon materials in aptamer immobilization and signal generation. The synthesis and properties of carbon nanotubes, graphene materials, carbon nitride, carbon black particles and fullerene are described and their implementation in the electrochemical biosensors are summarized. Examples of electrochemical aptasensors are classified in accordance with the content of the surface layer and signal measurement mode. In conclusion, the drawbacks and future prospects of carbon nanomaterials’ application in electrochemical aptasensors are briefly discussed. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.R.S. acknowledges support of the state subsidy in the sphere of scientific activity for Kazan Federal University (proposal No 0671-2020-0063). T.H. acknowledges funding from the Science Grant Agency VEGA, project No.: 1/0419/20

Voltammetric Sensor with Replaceable Polyaniline-DNA Layer for Doxorubicin Determination

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim New voltammetric DNA sensor has been developed on the base of glassy carbon electrode covered with electropolymerized polyaniline with entrapped native DNA saturated with Methylene blue. The thickness and redox properties of the coating are easily regulated by the number of potential cycles and pH of the solution. Doxorubicin competes with Methylene blue for DNA binding sites and suppresses the electron transfer within the layer. The measurement of the decay of the cathodic peak current made it possible to determine down to 0.01 nM doxorubicin. After that, DNA can be replaced by consecutive treatment of the biosensor with concentrated HCl and fresh DNA solution. Second involvement of DNA was confirmed by electrochemical impedance spectroscopy. The DNA sensor developed was tested on artificial samples mimicking ionic content of human serum and on commercial drug formulation containing doxorubicin

Dopamine Sensor Based on a Composite of Silver Nanoparticles Implemented in the Electroactive Matrix of Calixarenes

A sensitive electrochemical sensor based on a composite containing silver nanoparticles and a redox active thiacalixarene with catechol fragments in the substituents at the lower rim has been developed and used for dopamine detection. The electrochemical investigation of thiacalixarene in homogeneous solution and on the electrode interface showed the reversible character of the redox conversion of catechol fragments and its involvement in the chemical reduction of silver which resulted in formation of uniform nanoparticles of 4-6nm in diameter. The use of such a material for electrode modification made it possible to record a high amplitude cathodic signal at -700mV that was proportional to the dopamine concentration within 1nM-1μM. (limit of detection 0.5nM). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

A whole-cell amperometric herbicide biosensor based on magnetically functionalised microalgae and screen-printed electrodes

We report the fabrication of an amperometric whole-cell herbicide biosensor based on magnetic retention of living cells functionalised with magnetic nanoparticles (MNPs) on the surface of a screen-printed electrode. We demonstrate that Chlorella pyrenoidosa microalgae cells coated with biocompatible MNPs and retained on the electrode with a permanent magnet act as a sensing element for the fast detection of herbicides. The magnetic functionalisation does not affect the viability and photosynthesis activity-mediated triazine herbicide recognition in microalgae. The current of ferricyanide ion was recorded during alternating illumination periods and biosensor fabricated was used to detect atrazine (from 0.9 to 74 M) and propazine (from 0.6 to 120 M) (the limits of detection 0.7 and 0.4 M, respectively). We believe that the methodology presented here can be widely used in fabrication of a number of whole cell biosensors since it allows for efficient and reversible cells immobilisation and does not affect the cellular metabolism. © 2011 The Royal Society of Chemistry

Polyaniline-DNA based sensor for the detection of anthracycline drugs

© 2015 Elsevier B.V. All rights reserved. New approach of the detection of anthracycline preparations intercalating native DNA has been proposed and realized in the assembly of electrochemical sensor. Glassy carbon was covered with polyaniline obtained by electropolymerization in the presence of native DNA and oxalic acid as doping agents. As was shown by impedimetric and voltammetric measurements, the surface coating obtained showed extended pH range of electrochemical activity and retained ability to interact with specific intercalators. The incubation of the sensor with anthracycline preparations resulted in regular decrease of electron transfer resistance and suppression of redox probe current (ferricyanide anion). In optimal conditions, the detection limits of 0.01 nM doxorubicin, 0.1 nM daunorubicin and 0.2 nM idarubicin were achieved. The replacement of oxalic acid with sulfuric acid as polymerization media as well as thermal denaturation of DNA resulted in disappearance of the response. The selectivity of DNA interaction detection was higher in weakly acidic media for impedimetric measurements and in HEPES, pH 7.0, for voltammetric detection. Albumin, blood plasma electrolytes and sulfanylamides do not interfere with anthracycline measurements. The electrochemical sensor developed was tested in the determination of doxorubicin in commercial preparation with 91-93% recovery

Electrochemical DNA-Sensor Based on Macrocyclic Dendrimers with Terminal Amino Groups and Carbon Nanomaterials

The assembling of thiacalix[4]arene-based dendrimers in cone, partial cone, and 1,3-alternate configuration on the surface of a glassy carbon electrode coated with carbon black or multiwalled carbon nanotubes has been characterized using cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. Native and damaged DNA were electrostatically accumulated on the modifier layer. The influence of the charge of the redox indicator and of the macrocycle/DNA ratio was quantified and the roles of the electrostatic interactions and of the diffusional transfer of the redox indicator to the electrode interface indicator access were established. The developed DNA sensors were tested on discrimination of native, thermally denatured, and chemically damaged DNA and on the determination of doxorubicin as the model intercalator. The limit of detection of doxorubicin established for the biosensor based on multi-walled carbon nanotubes was equal to 1.0 pM with recovery from spiked human serum of 105–120%. After further optimization of the assembling directed towards the stabilization of the signal, the developed DNA sensors can find application in the preliminary screening of antitumor drugs and thermal damage of DNA. They can also be applied for testing potential drug/DNA nanocontainers as future delivery systems. © 2023 by the authors.Russian Science Foundation, RSF: 21-73-20067This research was funded by the Russian Science Foundation (grant 21-73-20067, https://rscf.ru/en/project/21-73-20067 (accessed on 3 May 2023))

Electrochemical behavior of pillar[5]arene on glassy carbon electrode and its interaction with Cu2+ and Ag+ ions

© 2014 Elsevier Ltd. All rights reserved. The electrochemical behavior of pillar[5]arene (P[5]A) and of its reaction products with Ag+ and Cu2+ ions has been investigated using cyclic voltammetry, optical methods and transmission electron microscopy (TEM). Stepwise oxidation of hydroquinone units of P[5]A molecule is guided by self-assembling and acid-base interactions. From one to three hydroquinone units per P[5]A molecule are oxidized depending on the measurement conditions. The deposition of P[5]A on glassy carbon electrode (GCE) partially blocks the electron transduction. Interfering influence of dissolved oxygen can be partially eliminated by the use of carbon black as immobilization matrix. The reaction of P[5]A with silver ions results in formation of most stable form with three benzoquinone and two hydroquinone units stabilized by quinhydrone-like structure. The Ag nanoparticles formed in the reaction retain electron transduction with the electrode due to involvement of shielding P[5]A molecules. Similar reaction with Cu2+ ions does not lead to stable products because of the formation of Cu2O particles detected by UV spectroscopy and TEM. Possible analytical applications of the materials obtained were proved by electrocatalytic reduction of hydrogen peroxide and mediated oxidation of thiocholine as model systems. In both cases, high sensitivity and wide range of the concentration determined were shown

Ag selective electrode based on glassy carbon electrode covered with polyaniline and thiacalix[4]arene as neutral carrier

Potentiometric sensor based on glassy carbon electrode covered with polyaniline and neutral carrier, e.g. thiacalix[4]arene containing pyridine fragments in the substituents in the lower rim has been developed and applied for determination of Ag+ ions in the range from 1.0 × 10-2 to 5.0 × 10-7 M with the response time of 12 s. The presence of thiacalixarene in the surface layer improves the reversibility and selectivity of the signal towards transient metal ions. The potentiometric selectivity coefficients were determined for various measurement conditions. As shown, the pH control and the use of NaF as a masking agent fully eliminate the interfering effect of Hg2+ and Fe3+ ions, respectively. The reaction of Ag+ with thiacalixarene was proved by the investigation of the extraction of picrate complexes of transient metals in the organic phase. The potentiometric sensor developed was successfully used for the potentiometric determination of silver sulfathiazole (Argosulfan™). © 2006 Elsevier B.V. All rights reserved

Discrimination of apple juice and herbal liqueur brands with solid-state electrodes covered with polyaniline and thiacalixarenes

Solid-contact ion-selective electrodes based on glassy carbon electrode covered with electropolymerized polyaniline and tetrasubstituted thiacalix[4]arene ionophores with hexyl and o-pyridylamido functional groups at the lower rim have been developed and examined in the discrimination of the brands of apple juices and herbal liqueurs. For this purpose, the liquids tested were diluted and spiked with a constant amount of Fe3+ ions. The variation of the signal toward Fe3+ ions was achieved due to their involvement in the reactions with the organic ligands and the antioxidants present. As was shown, the combination of the three electrodes with various receptors makes it possible to predict the brand of apple juices and herbal liqueurs using linear discriminant analysis in 95-100% cases. The discrimination procedure makes it possible to discriminate liquids within 20 min. Besides, the electrodes developed make it possible to detect individual antioxidants (ascorbic, malic, oxalic acids, hydroquinone, and quercetin) in the range from 5.0 × 10-6 to 1.0 × 10-2 M in direct potentiometric measurements and redox titration. © 2010 Elsevier B.V. All rights reserved