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We report herein a Pt(IV) prodrug with metronidazole in axial positions

We report herein the design, synthesis, and biological investigation of a series of novel Pt(IV) prodrugs with non-steroidal anti-inflammatory drugs naproxen, diclofenac, and flurbiprofen, as well as these with stearic acid in the axial position. Six Pt(IV) prodrugs

We report on the amperometric second-generation glucose test strips with the linear calibration range covering blood glucose concentrations. Chitosan membrane was used for immobilization of both enzyme and mediator in a single step. Optimal chitosan concentration in membrane-forming mixture corresponds to the highest enzyme activity and dramatically improved mediator adsorption in final membrane. On one hand, the immobilized glucose oxidase activation with an increase of the chitosan polymer content in the membrane has been noticed. On the other hand, positively charged chitosan matrix retains mediator (hexacyanoferrate (III) ion) in the membrane, due to its negative charge. Additionally, the excessive adsorption of the mediator on screen-printed electrodes coated with membranes was proved by means of cyclic voltammetry and impedance spectroscopy. Glucose test strips have been elaborated via single-step modification of the sensor support with the enzyme-mediator-polymer mixture. Apparently, the record linear calibration range from 1 mM to 50 mM glucose was achieved recording amperometric response at 5

We report on Prussian Blue based nanozymes, comparable in size with a natural enzyme peroxidase. Protein-sized nanoparticles have been synthesized in the course of reduction of ferric ion (Fe

A series of 73 ligands and 73 of their Cu+2 and Cu+1 copper complexes with different geometries, oxidation states of the metal, and redox activities were synthesized and characterized. The aim of the study was to establish the structure-activity relationship within a series of analogues with different substituents at the N(3) position, which govern the redox potentials of the Cu+2/Cu+1 redox couples, ROS generation ability, and intracellular accumulation. Possible cytotoxicity mechanisms, such as DNA damage, DNA intercalation, telomerase inhibition, and apoptosis induction, have been investigated. ROS formation in MCF-7 cells and three-dimensional (3D) spheroids was proven using the Pt-nanoelectrode. Drug accumulation and ROS formation at 40-60 μm spheroid depths were found to be the key factors for the drug efficacy in the 3D tumor model, governed by the Cu+2/Cu+1 redox potential. A nontoxic in vivo single-dose evaluation for two binuclear mixed-valence Cu+1/Cu+2 redox-active coordination compounds, 72k and 61k, was conducted.

We first report on constant potential (dc) amperometric flow-injection analysis (FIA) transduced by electroactive (conductive) polymers. Amperometric response is caused by the polymer recharging in order to maintain the electrode potential at a constant level when (i) ions are crossing the film|solution interface and polarizing electrode|film interface or (ii) ions or neutral molecules are specifically interacting with the polymer recharging it. The response under constant solution flow is a current peak and in flow-injection mode is a couple of current peaks directed opposite of the first sharp, analytically valuable peak. In both constant flow and flow-injection regimes, the peak current is dependent on analyte concentrations; obviously, the FIA mode provides more advantageous analytical characteristics. Constant potential amperometric flow-injection analysis is shown for boronate- and sulfate-functionalized polyanilines as well as for Prussian Blue, a member of the inorganic polymer family. As a proof of concept, the successful dc amperometric detection of lactate in human sweat with boronate-functionalized polyaniline has been shown. The proposed approach would revolutionize the field of conductive/electroactive polymer-supported ion sensing with the introduction of reliable and robust amperometry as a valuable alternative to existing potentiometry.

The review is dedicated to polymers of 2- and 3-aminophenylboronic acid. In contrast to the majority of other conducto- and impedimetric sensors, the ones developed by the authors can discriminate between specific and unspecific processes: conductivity as an analytical signal of the sensor is increasing upon specific binding being opposite to the result of an unspecific process. The increase of conductivity as a result of a specific process is demonstrated for the first time by our group, and the effect was confirmed by physicochemical investigations. The developed sensors are applicable to aerosol analysis as well as to aqueous media. Human whole sweat analysis performed by the sensors succeeded to determine the concentration of lactate (which is recognized as a hypoxia marker and the second important metabolite after in clinical diagnostics) in the range of 10−40 mM. The developed sensors are also applicable to reagentless mold detection in bioaerosols in the concentrations in the range 200−800 CFU/m3 that includes Russian hygienic standard for locality (500 CFU/m3).

In this work we propose a flow injection amperometry at constant potential as a perspective alternative to classical potentiometry for solid contact ion-selective electrodes (SC-ISEs). The amperometric readout mode eliminates the problem of background drift and potential instability – common limitations of potentiometry for SC-ISEs. The selectivity in flowinjection and constant flow amperometric modes is similar to the potentiometric one. Moreover, flow injection amperometry in comparison to potentiometry for ion-selective electrodes provides a shorter response time, within 15–30 s, by two orders of magnitude decreased detection limit and 5-6 fold increased signal-to-noise ratio. The proposed approach is an attractive readout mode that opens new horizons for the improvement of performance characteristics of solid contact ISEs.

The majority of reagentless affinity sensors suffer from poor selectivity because specific binding and non-specific interactions generate responses in the same direction, commonly causing resistance increase. We report on the advanced transducer, synthesized in course of molecular imprinting, which generates conductivity increase as a result of specific binding. Electropolymerization of 3-aminophenylboronic acid (3-APBA) known to yield conductive polyaniline only in the presence of F−, has been carried substituted the latter for hydroxy acids. The achieved synthesis of conductive polymer in course of fluoride-free 3-APBA electropolymerization indicates successful imprinting of hydroxy acids. Imprinting poly(3-APBA) provides as 10–15 times increased, as even decreased binding constants towards target analytes as compared to the non-imprinted polymer. This allows one to achieve the desired selectivity among polyols. Tuning binding properties of boronate functionalized polyaniline we’ve demonstrated the enzyme-free selective detection of saccharides and hydroxy acids via conductivity increase of the conductive polymer.

Electropolymerization of aminophenylboronic acids proceeds by the mechanism typical of conducting polyaniline, if the substituent in the ring is the electron donor and its position favors the electrophilic substitution into the para position with respect to the amino group in the ring. For the same reason, the polymerization of meta-aminophenylboronic acid requires the presence of fluoride ions to transform the weak electron acceptor, boronic acid group into the electron-donating trifluoroborate anion. It is shown that electropolymerization of ortho-aminophenylboronic acid can be carried out in strongly acidic media in the absence of fluoride ions, in analogy to unsubstituted polyaniline. The conductivity of the resulting polyanilineboronic acids synthesized under optimal conditions increases upon their binding with sugars and oxyacids, which allows detecting the specific interactions only, while the nonspecific interactions lower down the polymer conductivity.

The reduction of activated 5-(indol-3-yl)pyrrolidin-2-ones leading to a mixture of the respective indolyl pyrrolidines and their borane complexes, as well as several other transformations indicate that the electrophilicity of carbonyl group in 5-indolylpyrrolidin-2-ones is significantly decreased.

For noninvasive diagnostics of hypoxia, we propose the nonenzymatic sensor based on screen-printed structures with the working surface modified in course of electropolymerization of 3-aminophenylboronic acid (3-APBA) with imprinting of lactate. Impedimetric sensor allows lactate detection in the range from 3 mM to 100 mM with the detection limit of 1.5 mM; response time is 2–3 min. Sensor sensitivity remains unchanged within 6 months of storage unpacked in dry state at a room temperature, which is unachievable for enzyme based devices. Analysis of human sweat with poly(3-APBA) based sensor is possible due to (i) much higher lactate content compared to other polyols and (ii) high sensor selectivity (Klactateglucose 0.9). The attractive performance characteristics of poly(3-APBA) based ...

We report on the novel reagentless and label-free detection principle allowing discrimination of specific binding over non-specific interactions. Unlike majority of impedimetric and conductometric (bio)sensors, which specific and unspecific signals are directed in the same way (resistance increase), making doubtful their real applications, the response of the reported system results in resistance decrease, which is directed oppositely to the background. The mechanism of the resistance decrease is the polyaniline self-doping, i.e. as an alternative to proton doping, an appearance of the negatively charged aromatic ring substituents in polymer chain. Negative charge at boronic ring substituent appears as a result of complex formation with di- and triols, i.e. specific binding. Thermodynamic data on interaction of the electropolymerized aminophenylboronic acids with saccharides and hydroxy acids indicate that the observed resistance decrease is due to polymer interaction with polyols. A possibility to detect microorganisms (Penicillum chrysogenum) on the basis of interdigitated electrodes modified with boronate substituted polyaniline is also shown. The first reported conductivity increase as a specific signal opens new horizons for reagentless affinity sensors.

Boronate-substituted polyanilines are able to serve as advanced affinity transducers if synthesized at their highest conductivity and remind properties (particularly, cyclic voltammograms in acidic media) of common conductive polyaniline. This presumes growing conditions, when the substituent promotes electrophilic substitution in para-position relatively amino-group. Thus electropolymerization of 3-aminophenylboronic acid (3-APBA) requires free fluoride ions to convert boronic acid residue to trifluoroborate serving as electron donor. On the contrary, when in ortho-position to amino-group, boronic acid does not hamper the polyaniline-type growth, but its conversion to trifluoroborate inhibits the polymerization. Accordingly, optimal media for electropolymerization of 2-aminobenzeneboronic acid (2-APBA) are strong acidic solutions similar to unsubstituted aniline. Conducting polyaniline-type polymers synthesized from both isomers generate an increase in their conductivity as a response to polyols (saccharides and hydroxy acids) according to the mechanism of self-doping by freezing negative charges in ring substituents upon complexation. This comprises the novel detection principle for reagentless affinity sensors, allowing to discriminate the specific affinity interactions from non-specific bindings. Keywords: Sensor, Polyaniline self-doping, Electropolymerization, Polyols, Conductivity

We report on the novel reagentless and label-free detection principle based on electroactive (conducting) polymers considering sensors for polyols, particularly, saccharides and hydroxy acids. Unlike the majority of impedimetric and conductometric (bio)sensors, which specific and unspecific signals are directed in the same way (resistance increase), making doubtful their real applications, the response of the reported system results in resistance decrease, which is directed oppositely to the background. The mechanism of the resistance decrease is the polyaniline self-doping, i.e., as an alternative to proton doping, an appearance of the negatively charged aromatic ring substituents in polymer chain. Negative charge "freezing" at the boron atom is indeed a result of complex formation with di- and polyols, specific binding. Changes in Raman spectra of boronate-substituted polyaniline after addition of glucose are similar to those caused by proton doping of the polymer. Thermodynamic data on interaction of the electropolymerized 3-aminophenylboronic acid with saccharides and hydroxy acids also confirm that the observed resistance decrease is due to polymer interaction with polyols. The first reported conductivity increase as a specific signal opens new horizons for reagentless affinity sensors, allowing the discrimination of specific affinity bindings from nonspecific interactions.