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•Highly sensitive and selective molecularly imprinted polymer-based electrochemical chiral (MIEC) sensors was fabricated for the detection of Pseudoephedrine (PSDO) enantiomers.•The ...developed (1S,2S)-PSDO@MIP/GCE sensor has an excellent selectivity towards (1R,2R)-PSDO with an imprinting factor of 4.97.•The proposed sensor was prepared with electropolymerization of o-PD monomer in the presence of (1S,2S)-PSDO.
In this study, simple, eco-friendly, highly sensitive, and selective molecularly imprinted polymer-based electrochemical chiral (MIEC) sensors were fabricated for the detection of Pseudoephedrine (PSDO) enantiomers. The sensitive and selective platform was prepared by in-situ electropolymerization of o-phenylenediamine (o-PD) on a glass carbon electrode in the presence of the template molecule, PSDO. The MIP modified sensor surface was characterized with Raman spectrometer, contact angle measurements, and scanning electron microscopy (SEM) to confirm successful preparation. Furthermore, cyclic voltammetry and electrochemical impedance spectroscopy were applied to test the electrochemical property of the sensor. Under the optimal conditions, the linear response of (1S,2S)-PSDO was obtained in the range of 1x10-15 − 1x10-14 M in the commercial human serum samples and effervescent tablets. Moreover, the high recovery data were obtained as 100.5 % and 100.4 % in pharmaceutical dosage forms and commercial human serum samples by the proposed (1S,2S)-PSDO@MIP/GCE sensor, respectively. The developed (1S,2S)-PSDO@MIP/GCE sensor has an excellent selectivity towards (1R,2R)-PSDO with an imprinting factor of 4.97.
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•Nano-In2O3 is found to be an efficient catalyst for three-component condensation.•In2O3 nanoparticles are recyclable without significant loss of catalytic activities.•Applicable to ...gram-scale synthesis of N-alkoxylated benzimidazoles.•Control experiments were done for mechanism studies.
A convenient method has been developed for the selective synthesis of N-alkoxylated benzimidazole derivatives by the cyclocondensation reaction of simple ortho-phenylenediamine, formaldehyde and alcohols in presence of indium oxide nanoparticles as catalyst. The alcohol acts as reactant as well as solvent in this reaction. No other solvents or additives have been used for this reaction. The catalyst can be reused several times without significant loss of catalytic activity. A probable reaction mechanism has been proposed based on some control experiments.
A ratiometric fluorescence method is described for the determination of the anticancer drug 6-mercaptopurine (6-MP). The method is based on the use of fluorescent MoS
quantum dots (MQDs) and of the ...enzyme horseradish peroxidase (HRP). In the absence of 6-MP, HRP catalyzes the oxidation of o-phenylenediamine (OPD) by H
O
to form 2,3-diaminophenazine (DAP). This leads to quenching of the violet fluorescence of MQDs (measured at excitation/emission wavelengths of 360/415 nm), while the strong yellow fluorescence of DAP (peaking at 560 nm) becomes increasingly strong. In the presence of 6-MP, however, it will be preferentially oxidized by the HRP/H
O
system to form a disulfide dimer. Hence, less H
O
is available for the oxidation of OPD and less DAP will be formed. This results in the recovery of the violet fluorescence and a decrease of the yellow fluorescence. The ratio of the two signals can be used to quantify either H
O
or 6-MP. Linear responses are observed for H
O
in 0.5-140 μM concentration range, and for 6-MP in the 0.5-70 μM concentration range, with detection limits of 0.1 μM and 0.29 μM, respectively. The method was applied to the determination of 6-MP in spiked human urine and gave satisfactory results. Graphical Abstract Schematic of an enzymatic fluorometric method for determination of 6-mercaptopurine (6-MP). It is based on the presence of 6-MP that can inhibit the HRP-catalyzed oxidation of o-phenylenediamine (OPD) to form 2,3-diaminophenazine (DAP). Hence, the fluorescence resonance energy transfer (FRET) between DAP and MoS
quantum dots (MQDs) is suppressed.
The effect of stereo electronic factors of amino anilines such as ortho-phenylenediamine (OPD) and para-phenylenediamine (PPD) on the fluorescence of 5,6-benzo-4-azidomethyl coumarin (5BAMC) in polar ...aprotic and polar protic solvents has been studied. From UV absorption and 1 H NMR studies, observed blue shift in the presence of PPD is due to H-bonding with 5BAMC. Fluorescence quenching studies indicate the role of static and dynamic quenching mechanisms for both the quenchers and larger quenching efficiency of PPD than OPD. The sphere of action static quenching and finite sink approximation models reveal static effect in the excited state and diffusion limited bimolecular quenching reactions. Electrochemical analysis indicates that quenching efficiency of PPD is more than OPD based on the magnitudes of free energy change for electron transfer. Binding equilibria analysis confirms that the magnitude of binding between PPD and 5BAMC is stronger compared to OPD. It is also noticed that the binding between PPD and 5BAMC in polar protic solvents is stronger than that in aprotic solvents. Lastly, from the magnitudes of thermodynamic parameters, interaction between PPD and 5BAMC is hydrophobic and spontaneous. Thus from the present investigation, it is concluded that the separation between two –NH2 groups in amino anilines plays role in their interaction with coumarin derivative 5BAMC.
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•A sorbent composite was one-step electrodeposited on a modified plaswood substate.•The sorbent composite had a large surface area and was highly porous.•The design of the substrate ...improved the extraction of PAHs in coffee drinks.•The device highly efficiently extracted PAHs in coffee drinks.•The developed device could be reused up to 18 times.
Coffee beans can be contaminated during roasting by polycyclic aromatic hydrocarbons (PAHs), some of which have been classified as carcinogens. An extraction device for PAHs in coffee drinks was designed with six compact DC motors rotating six sorbents. The sorbents were plaswood propellers modified by one-step electrodeposition of a poly(ortho-phenylenediamine) and Zn composite (PoPD-Zn). Benzo(a)anthracene (BaA), chrysene (Chry), benzo(b)fluoranthene (BbF), and benzo(a)pyrene (BaP) were chosen as representative PAHs. Scanning electron micrographs of the PoPD-Zn showed a porous structure. The extracted PAHs were quantified by gas chromatography coupled with a flame ionization detector. Detected concentrations of PAHs in coffee drink samples were as follows: BaA 1.4 ± 0.4 to 16.5 ± 0.8 µg L−1; Chry 0.5 ± 0.2 to 2.1 ± 0.5 µg L−1; BbF 2.2 ± 0.6 µg L−1; and BaP 6.2 ± 1.0 µg L−1. Good recoveries ranging from 82.7 ± 1.9% to 99.0 ± 0.5% were obtained.
A poly(ortho-phenylenediamine-co-aniline) copolymer is synthesized via the oxidative route, using a 1:1 M ratio of aniline to ortho-phenylenediamine (oPDA) and ammonium persulfate as the oxidizing ...agent. Infrared spectroscopy indicates that the copolymer contains the functional groups typically present in polyaniline and poly(ortho-phenylenediamine); whereas UV-vis-NIR spectroscopy shows that the copolymer adopts a phenazine-type structure. Cyclic voltammetry evidences the copolymer synthesis, as a redox peak at −65 mV, different from those exhibited by polyaniline (160 mV and 600 mV) or poly(o-phenylenediamine) (−240 mV) is observed. Finally, electrochemical impedance spectroscopy and the charge/discharge test provide support to propose the copolymer application in electrodes for supercapacitors.
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•Polyaniline electrochemical properties are modified by copolymerization.•Copolymer structure strongly influences the specific capacitance.•Phenazine units provide greater stability during the charge/discharge cycles.
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•A new configuration of IT-SPME based on a thin-film coating was introduced.•Electrodeposited Poly(ortho-phenylenediamine with long lifetime was used as a sorbent.•To study the ...applicability of IT-SPME, chlorophenols (CPs) were selected as model analytes.•Separation and determination of CPs were performed with HPLC-UV.•The method was used for the extraction of model analytes from rain water and honey samples.
In the present research, in-tube solid phase microextraction and thin-film microextraction were combined in a new configuration in order to use the advantages of both techniques. For this purpose, poly(ortho-phenylenediamine) thin-film was electrodeposited on stainless-steel sheets. The sheets were inserted into a cartridge. The resulting configuration was used for in-tube solid phase microextraction of chlorophenols as model analytes. The analytes were separated and detected by high performance liquid chromatography coupled with ultraviolet detection. The important factors affecting the extraction such as the pH (6) and salt concentration of the sample solution (0%), extraction time (15 min), extraction and desorption flow rates (6 mL min−1 and 70 µL min−1, respectively), and desorption solvent type and volume (methanol, 500 µL) were optimized. The presented method can detect model analytes at concentrations as low as 0.3 µg L−1. The method showed good linearity in the range of 0.8–100.0 µg L−1 of chlorophenols with coefficients of determination better than 0.9945. The intraday and interday precisions were in the range of 1.3–5.8% and 3.5–8.3%, respectively. The tube-to-tube repeatability of the method was lower than 13.0%. Finally, the validated method was successfully used for the analysis of the selected analytes in real samples including rain water and honey.
A poly-o-phenylenediamine film modified glassy carbon electrode (PoPD/GC) was successfully prepared by cyclic voltammetry in acetate buffer solution. The polymerization mechanism of oPD is discussed. ...The impedance behavior and morphology of the PoPD membrane were characterized using cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy, respectively. It is discovered that the PoPD/GC prepared only in acetate buffer solution had dual electrocatalytic activity toward the oxidation and reduction of H
2
O
2
. The optimal buffer solution pH, scanning rate, monomer concentration, and number of scannings for film forming were 4.2, 0.05 V s
−1
, 6.0 mmol L
−1
, and 30, respectively. The linear ranges between the anodic (Δi
a
) or cathodic (Δi
c
) current and H
2
O
2
concentration were 0.07−1.0 × 10
4
and 0.04−4.5 × 10
4
μmol L
−1
, respectively. The corresponding calibration curves were Δi
a
(μA) = 8.03c (mmol L
−1
) + 6.36 (n = 18, R
2
= 0.9989) and Δi
c
(μA) = −5.52c (mmol L
−1
) − 0.77 (n = 18, R
2
= 0.9990) with a detection limit of 0.03 and 0.02 μmol L
−1
(S/N = 3), respectively. The PoPD/GC prepared in the optimal conditions showed good stability and quick response (<0.2 s) to H
2
O
2
, which was successfully applied to the determination of H
2
O
2
in real water samples with satisfactory results.
There is a growing interest in the technological transfer of highly performing electrochemical sensors within portable analytical devices for the in situ monitoring of environmental contaminants, ...such as perfluorooctanesulfonic acid (PFOS). In the redesign of biomimetic sensors, many parameters should be taken into account from the working conditions to the electrode surface roughness. A complete characterization of the surface modifiers can help to avoid time-consuming optimizations and better interpret the sensor responses. In the present study, a molecularly imprinted polymer electrochemical sensor (MIP) for PFOS optimized on gold disk electrodes was redesigned on commercial gold screen-printed electrodes. However, its performance investigated by differential pulse voltammetry was found to be poor. Before proceeding with further optimization, a morphological study of the bare and modified electrode surfaces was carried out by scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS), atomic force microscopy (AFM) and profilometry revealing an heterogeneous distribution of the polymer strongly influenced by the electrode roughness. The high content of fluorine of the target-template molecule allowed to map the distribution of the molecularly imprinted polymer before the template removal and to define a characterization protocol. This case study shows the importance of a multi-analytical characterization approach and identify significant parameters to be considered in similar redesigning studies.
Zn-containing proteins play essential roles in the viability and virulence of bacteria, so are considered to be possible molecular new drug targets. Based on literature data about ...N-acyl-o-phenylenediamine and 2-pycolylamine as warheads of drugs and molecular probes for Zn-bearing enzymes like histone deacetylases, we guessed that N-(7-nitrobenzofurazan-4-y)-o-phenylenediamine (NBD-OPD), 2-pycolyl-(N-(7-nitrobenzofurazan-4-amine)) and ciprofloxacin 2-pycolylamide (CPF-Pic2) are potential fluorescent inhibitors of such enzymes. Molecular docking was performed for estimate affinity of the compounds to a set of bacterial enzymes, and photochemical and electrochemical properties were calculated in silico using DFT.
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