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For the first time, a Ti3C2Tx–MXene and poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) composite-modified electrode has been developed for electrochemical detection of the bilirubin (BR) by molecularly imprinted ortho-phenylenediamine (o–PD). BR is a biomarker for liver-related diseases. High levels of BR imply liver dysfunction; hence, its exact and rapid measurement is indispensable to its immediate diagnosis and treatment. The synergistic effects of MXene and PEDOT: PSS not only enhanced the electrochemical conductivity and provided a large electroactive surface area for better MIP polymerization but also improved the sensitivity, stability, and electro-catalytic activity of the developed electrode. This is the first study to combine MXene/PEDOT: PSS and molecularly imprinted orthophenylenediamine for BR sensing, which individually have demonstrated potential, but whose combined effects have never been explored in the context of BR detection. The successful synthesis and deposition of composite is confirmed by field emission scanning electron microscopy (FESEM) along with energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The electrochemical properties and surface morphology of the prepared electrode at every modification step were characterized by electrochemical techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS), and FESEM respectively. The MXene/PEDOT: PSS composite as an electrode modifier exhibited sensing of BR in the clinical relevant range of BR in human serum 0.1–20 mg/dL with a detection limit of 0.002 mg/dL. Additionally, the prepared electrode has excellent reproducibility, stability, selectivity, and repeatability and also showed acceptable results for the sensing of BR in human serum sample. [ABSTRACT FROM AUTHOR]

A sensitive molecularly imprinted poly‐(ortho‐phenylenediamine) electrochemical sensor was fabricated for selective melamine detection in milk and infant formula. The pencil graphite electrode (PGE) was modified by deposition of Au nanoparticles and reduced graphene oxide (RGO) on its surface. The fabrication of the electrode in various stages was monitored using cyclic voltammetry. The immobilized RGO, MIP, and gold nanoparticles on the PGE surface were morphologically characterized by field‐emission scanning electron microscopy (FESEM). Under the optimized conditions, the linear range and the limit of detection (LOD) were 10–17–10–8 M and 2.64 × 10–16 M (S/N = 3), respectively. The prepared sensor exhibited a good reproducibility and repeatability response. The recovery range of melamine‐spiked milk and infant formula was 92.7%–103.9% and 93.5%–105.8%, respectively. The sensor could apply successfully for melamine determination in milk and infant formula samples. [ABSTRACT FROM AUTHOR]

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.

Abstract 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 –NH 2 groups in amino anilines plays role in their interaction with coumarin derivative 5BAMC. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

The formation of a nanocomposite coating based on reduced graphene oxide (RGO) and poly(o-phenylenediamine) (PPD) in the chemical reaction of graphene oxide (GO) and o-phenylenediamine (OPD) has been studied by cyclic voltammetry (CVA), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It has been shown that the action of cyclic polarization provides a more uniform structure of the nanocomposite films (decrease in the corrugation effect). In addition, it has been found that the polarization of GO films containing the OPD monomer distributed inside to the PPD synthesis potentials leads to the formation of uniformly distributed globular structures, which most probably correspond to a polymer electrochemically synthesized in the space between the GO nanosheets. [ABSTRACT FROM AUTHOR]

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.

Silica sulfuric acid is found to catalyze efficiently the condensation of o-phenylenediamines with various linear and cyclic ketones to afford the corresponding 1,5-benzodiazepines in quantitative yields under solvent-free conditions at room temperature

Phương pháp nhanh chóng và hiệu quả ứng dụng sự hỗ trợ của vi sóng đã được phát triển thành công để tổng hợp các dẫn xuất 2-benzimidazolyl-4-oxo-4H quinolizine. Bằng phương pháp này, ba dẫn xuất 2-(1H-benzimidazol-2-yl)-4H-quinolizin-4-one đã được tổng hợp từ 4-oxo-4H-quinolizine-2-carbaldehyde với các ortho-phenylenediamine hoặc ortho-nitroaniline sử dụng Na2S2O4 hoặc Na2S2O5 làm tác nhân oxy hóa. Trong cả ba trường hợp khảo sát đều cho hiệu suất tổng hợp cao (76-92%) và thời gian tổng hợp ngắn (tối đa 10 phút). Cấu trúc của các dẫn xuất 2-(1H-benzimidazol-2-yl)-4H-quinolizin-4-one mới được xác định bằng các phương pháp phổ nghiệm 1H-NMR, 13C-NMR và MS.

Highlights: [•] Structural characterization of non conductive electropolymerized oPD thin films. [•] Gallic acid capacitive sensing. [•] Impedance spectroscopy. [•] Raman spectra. [•] DFT calculations. [ABSTRACT FROM AUTHOR]

We report on an electrode for the amperometric determination of lorazepam. A glassy carbon electrode was coated with a molecular imprint made by electropolymerization of ortho-phenylenediamine and filled with multiwalled carbon nanotubes and gold nanoparticles, which enhances the transmission of electrons. The sensor was studied with respect to its response to hexacyanoferrate (III) as a probe and by electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry. The linear response range to Lorazepam is from 0.5 nM to 1.0 nM and from 1.0 nM to 10.0 nM, with a detection limit of 0.2 nM (at an S/N of 3). The electrode was successfully applied to determine Lorazepam in spiked human serum. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The carcinogenicity of ortho-phenylenediamine ( o-PD) was examined by administrating o-phenylenediamine dihydrochloride ( o-PD2HCl) in dinking water to groups of 50 F344/DuCrj rats and 50 Crj:BDF mice of both sexes for 2 years. The drinking water concentration of o-PD2HCl was 0, 500, 1,000 or 2,000 ppm (wt/wt) for male rats; 0, 250, 500 or 1,000 ppm for female rats; 0, 500, 1,000 or 2,000 ppm for male mice; and 0, 1,000, 2,000 or 4,000 ppm for female mice. Two-year administration of o-PD2HCl produced a dose-dependent increase in the incidences of hepatocellular adenomas and carcinomas in rats of both sexes and in female mice, and hepatocellular adenomas in male mice. In mice, the incidences of hepatocellular adenomas were increased at the lowest dose used in both males and females. Metastasis from hepatocellular carcinomas of rats occurred predominantly in the lung. Incidences of transitional cell papillomas and carcinomas in the urinary bladder were noted in male rats administered 2,000 ppm, together with an increased incidence of papillary and/or nodular hyperplasia of transitional epithelium. In mice, the incidence of papillary adenomas in the gall bladder, which is rare in mice, was increased in both males and females administered 2,000 ppm. Thus, o-PD is carcinogenic in two species, i.e., rats and mice of both sexes. [ABSTRACT FROM AUTHOR]

Abstract: A bilayer amperometric nitrate biosensor with an integrated permselective layer has been developed for exclusion of inorganic anion and cation interferences. The inner PPy(polypyrrole)–NaR–NADH layer of the biosensor is formed by galvanostatic polymerization of pyrrole (Py) in presence of nitrate reductase (NaR) and nicotinamide adenine dinucleotide (NADH), followed by formation of the outer permselective poly-ortho-phenylenediamine (P-o-PDA) layer by potentiodynamic polymerization of ortho-phenylenediamine (o-PDA). The exclusion efficiency (E eff) of the outer layer in rejecting inorganic cation and anion interferences is evaluated by a new proposed relationship. 73–87% and 47–84% of anion and cation interferences, respectively, were efficiently rejected with the permselective layer. Further improvement in the exclusion efficiency for cations was accomplished by combining the use of the outer layer with the addition of 1mM EDTA into the measurement solution. The addition of EDTA improved the E eff achieved for cation rejection by 10–40% to give net E eff of 89–94%. The inclusion of the outer layer also aided the retention of NaR and NADH in the inner PPy–NaR–NADH layer and, hence, enabled improved amperometric detection of nitrate, achieving a detection limit of 0.20μM and a linear concentration range of 10–500μM with a 3.4%rsd (n =10). [Copyright &y& Elsevier]

One-pot synthesis of benzimidazole compounds from ortho-phenylenediamine and a variety of aldehydes was developed under mild reaction conditions. All the reactions were carried out in the presence of samarium triflate (10 mol%) in acetonitrile at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: The addition of the ortho-phenylenediamine (OPDA) to aniline solution resulted in a slower polymer synthesis rate and in the modified PANI structural change. The interaction of both monomers produced the change in PANI morphology, which was confirmed by atomic force microscope (AFM). The stainless steel (SS) corrosion protective properties of PANI and modified PANI coatings were examined in chloride (Cl−) media by open circuit potential (Eo.c . vs. t) monitoring. The presence of Cl− in supporting electrolyte resulted in two different Eo.c. vs. t potential regions. The different Eo.c. “drop” in two specific potential regions was attributed to the facilitated and hindered Cl− flux through PANI towards the SS surface. The Cl− flux was found to be governed by the potentially dependant “pump” and “barrier” effects, which were explained to be governed by the PANI anion exchange property. It has been found that the polymer structure has a significant influence on the electroactive behavior of the modified PANI. The influence of the polymer structure on the “barrier” and “pump” effects was additionally investigated by adding OPDA. The denser polymer structure obtained by addition of OPDA resulted in “weakened pump” and “enhanced barrier” effects, which produced hindered Cl− flux. The anion exchange process detected by electrochemical impedance spectroscopy (EIS) in the low frequency region and the PANI anion exchange property were found to be under the influence of the OPDA additions. An increase in OPDA addition resulted in a lower polymer ability to replace the anions, which consequently hindered the process detected in the low frequency region. The method proposed in this paper offers the possibility to predict the modified PANI corrosive protective properties of SS in Cl− media using EIS measurement, which is less time consuming than the long-lasting Eo.c. vs. t measurements. [Copyright &y& Elsevier]

Abstract: Oxidative electropolymerization of aniline (Ani) in phosphoric acid (H3PO4) on composite 2B pencil graphite was accomplished using selected inorganic salts as supporting electrolytes. These salts determined the degree of conductivity of polyaniline (PAni) formed. The conductivity was in the order of CaCl2 >KCl>ZnCl2 >ZnSO4 >Ca3(PO4)2. The three pairs of redox peaks in the voltammogram of PAni formed in the presence of 0.06M Ca3(PO4)2 and 0.2M ZnSO4 have shifted 300mV to the negative potential. The shifting of peaks is strongly influenced by type of anions'' presence in the salts. However, the nature of the available cations had no significant effect. The negative shifts of redox peaks were exploited to facilitate the electrocopolymerization of Ani and ortho-phenylenediamine (oPD). The formation of the poly(Ani-co-oPD) was confirmed by the FTIR spectra. [Copyright &y& Elsevier]

Kinetics of ortho-phenylenediamine (PDA) oxidation has been investigated in the “pseudoperoxidase” system, Methemalbumin-H2O2, in the presence of 2-amino-4- tert-butylphenol (ATBP), 2-amino-4,6-di tert-butylphenol (ADTBP) and its four N-acyl derivates, as well as flavonoids (quercetin, morin, silibin, hesperidin and naringin). Under standard experimental conditions (20°C, phosphate buffered saline, pH 7.4, containing 5.25% ethanol and DMF) ATBP, ADTBP and two its N-acyl-derivatives and also all five flavonoids inhibited PDA oxidation with different efficiency, which was characterized in terms of the inhibition constants, Ki, M, or the percent of inhibition degree at the maximal concentrations of these inhibitors. Quercetin (Ki = 7.7 × 10−5 M) and ATBP (Ki = 1.26 × 10−4 M) were the most effective antioxidants. Using these characteristics and other required criteria, the pairs PDA-quercetin and PDA-ATBP were proposed for a practical application in the test-systems for evaluation of total antioxidant activity of biological objects. [ABSTRACT FROM AUTHOR]

Abstract: One-dimensional (1D) nanobelts of several hundred micrometers in length, several hundred nanometers in width and several hundred nanometers in height are obtained by direct mixing of ortho-phenylenediamine (oPD) and FeCl3 aqueous solution at room temperature. The nanobelts were characterized by elemental analysis, liquid chromatography/mass spectrometry (LC/MS), NMR (1H and 13C), FT-IR, UV–vis, thermogravimetric (TG) and conductivity measurement. The nanobelts are identified as 2,3-diaminophenazine assemblies. The formation of the nanobelts involves two stages: (1) oxidation of oPD by FeCl3, yielding individual 2,3-diaminophenazine molecules; and (2) self-assembly of the 2,3-diaminophenazine, forming the 1D nanobelts. The nanobelts exhibit fairly high thermal stability and show conductivity at the level of semiconductors. [Copyright &y& Elsevier]

Abstract: There is an association between occupational exposure to hair dyes and incidence of cancers. Permanent oxidant hair dyes are consisted of many chemical components including ortho-phenylenediamines. To clarify the mechanism of carcinogenesis by hair dyes, we examined DNA damage induced by mutagenic ortho-phenylenediamine (o-PD) and its derivatives, 4-chloro-ortho-phenylenediamine (Cl-PD) and 4-nitro-ortho-phenylenediamine (NO2-PD), using 32P-labeled DNA fragments obtained from the human p16 and the p53 tumor suppressor gene. We also measured the content of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), a marker of oxidative DNA damage, in calf thymus DNA with an electrochemical detector coupled to a high performance liquid chromatograph. Carcinogenic o-PD and Cl-PD caused Cu(II)-mediated DNA damage, including 8-oxodG formation, and antioxidant enzyme superoxide dismutase (SOD) enhanced DNA damage. o-PD and Cl-PD caused piperidine-labile and formamidopyrimidine-DNA glycosylase-sensitive lesions at cytosine and guanine residues respectively in the 5′-ACG-3′ sequence, complementary to codon 273, a well-known hotspot of the human p53 tumor suppressor gene. UV–vis spectroscopic studies showed that the spectral change of o-PD and Cl-PD required Cu(II), and addition of SOD enhanced it. This suggested that SOD enhanced the rate of Cu(II)-mediated autoxidation of o-PD and Cl-PD, leading to enhancement of DNA damage. On the other hand, mutagenic but non-carcinogenic NO2-PD induced no DNA damage. These results suggest that carcinogenicity of ortho-phenylenediamines is associated with ability to cause oxidative DNA damage rather than bacterial mutagenicity. [Copyright &y& Elsevier]

Abstract: A widely used generic assay for 2-oxoglutarate-dependent oxygenases relies upon monitoring the release of 14CO2 from labeled [1-14C]-2-oxoglutarate. We report an alternative assay in which depletion of 2-oxoglutarate is monitored by its postincubation derivatization with o-phenylenediamine to form a product amenable to fluorescence analysis. The utility of the procedure is demonstrated by assays with hypoxia-inducible factor hydroxylases where it was shown to give results similar to those reported with the radioactive assay, but it is more efficient and readily adapted to a multiwell format. The process should be amenable to the assay of other 2-oxoglutarate-consuming enzymes and to the discovery of inhibitors. [Copyright &y& Elsevier]

The peroxidase-catalyzed oxidation of 3,3",5,5"-tetramethylbenzidine (TMB), ortho-phenylenediamine (PDA), and 5-aminosalicylic acid (5-ASA) is significantly accelerated in the presence of 2-aminothiazole (AT) and melamine (MA), and an increase in their concentrations is associated with a parallel increase in the kcat and Km values for TMB and PDA. The activation of the peroxidase-catalyzed oxidation of TMB and PDA is quantitatively characterized by a coefficient (degree) α (M–1) which significantly depends on pH in the range 6.2-6.4, 6.4-7.4, and 6.0-7.4 for the TMB–AT, TMB–MA, and PDA–MA pairs, respectively. An increase in the coefficient α with increase in pH confirms nucleophilicity of activation of the peroxidase-catalyzed oxidation of the aromatic amines in the presence of AT and MA. Under optimal conditions the coefficients α for the TMB–AT, PDA–AT, TMB–MA, and PDA–MA pairs vary in the limits of (1.90-3.53)·103 M–1. [ABSTRACT FROM AUTHOR]

The mutagenic potential of ortho-phenylenediamine - known by studies on Salmonella typhimurium - was studied in mice, Chinese hamsters and Guinea pigs with the use of the micronucleus test. In bone marrow of all three species, chromosomal damage was detected following intraperitoneal injections of the test chemical, this damage was seen also after peroral administration to mice. Four derivatives of ortho-phenylenediamine containing one or two methyl-, nitro- or chlorosubstituents in 4- or 5-position of the aromatic ring were studied in mice. Of these the 4-methyl-derivative induced micronuclei, the 4-nitro-, 4,5-dimethyl-, and 4,5-dichloroderivatives were inactive. The results indicate that the chemical nature and the number of substituents influence the chromosome damaging potential. [ABSTRACT FROM AUTHOR]

A new compound, 1,3,5-tris-(2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-1,2,3,4,5,6-hexahydro-s-triazine was obtained by the reaction of ortho-phenylenediamine 1 with 1,3,5-triacryl-1,2,3,4,5,6-hexahydro-1,3,5-triazine 2. Spectroscopic (IR, 1H-NMR, 13C-NMR and MS) data are supplied to support the proposed structure for the title compound. [ABSTRACT FROM AUTHOR]

• Nano-In 2 O 3 is found to be an efficient catalyst for three-component condensation. • In 2 O 3 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. [ABSTRACT FROM AUTHOR]

• Carrageenan sulfate groups doped to the conductive copolymer. • Composite morphology is variable, depends on iota -carrageenan content. • Conductivity and electroactivity can be tuned by iota -carrageenan loading. A series of poly(ortho -phenylenediamine- co -aniline)/ iota -carrageenan biocomposites were synthesized via oxidative polymerization. Infrared spectroscopy revealed the ionic interaction between the sulfate groups in iota -carrageenan (i-CRG) and the quaternary amine groups in the copolymer, demonstrating that i-CRG exerts the function as the dopant. Cyclic voltammetry showed redox potentials around 35 mV, indicating that the i-CRG presence does not constrain electroactivity. Additionally, the biocomposites presented ionic and electrical conductivity (in the range of 10−5-10-3 S cm-1) determined respectively by electrochemical impedance spectroscopy and the four-point technique. Interestingly, it was observed by scanning electron microscopy that i-CRG played the role as a template since its presence, depending on the weight ratio respecting the copolymer, caused copolymer morphology modification. This set of properties is highly advantageous due to the combination of conduction mechanisms and electroactive behavior, which can be used in applications related to energy storage devices such as supercapacitors and chemical sensors. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 MoS2 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 H2O2 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/H2O2 system to form a disulfide dimer. Hence, less H2O2 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 H2O2 or 6-MP. Linear responses are observed for H2O2 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.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 MoS2 quantum dots (MQDs) is suppressed. [ABSTRACT FROM AUTHOR]

The authors describe a dual-mode (colorimetric-fluorometric) nanoprobe for H2O2 that was fabricated by covering molybdenum disulfide nanosheets (MoS2 NS) with ortho-phenylenediamine (OPD). The probe (OPD-MoS2 NS) was applied to the optical determination of H2O2, to the quantitation of cell numbers, and to the detection of intracellular concentrations of H2O2. Oxidation by H2O2 leads to a colored and fluorescent product (oxidized OPD) with absorption/excitation/fluorescence peaks at 450/450/557 nm. The nanoprobe can detect H2O2 in down to 500 nM concentrations, and HeLa cells at levels of 100 cells mL−1. The detection limit for intracellular H2O2 is in the 5.5 to 12.6 μM concentration range when the method is applied to cells at levels of 102-106 cells mL−1. Due to its good biocompatibility and easy cell uptake, the nanoprobe also permits sensitive fluorometric imaging of intracellular H2O2. It can also comparatively discriminate the change of intracellular oxidation state in living cancerous and normal cells.A dual-mode (colorimetric-fluorometric) detection nanoplatform based on OPD-modified MoS2 nanosheets is used to quantitatively detect H2O2, cell numbers and intracellular H2O2. The MoS2 nanoprobes also permit sensitive fluorescence imaging of intracellular H2O2, and can discriminate intracellular oxide states in living cancerous and normal cells. [ABSTRACT FROM AUTHOR]

The development of fingerprints in blood on a dark-coloured surface can be difficult. Contrast between the bloodmark and the surface can be difficult to achieve using photography and chemical reagents. The use of haem-reagent ortho-Phenylenediamine (OPD) and Zar-Pro™ strips in the enhancement of bloody impressions were investigated. Depletions of bloodmarks were deposited on black ceramic tiles and aged up to 90 days. OPD, Acid Yellow 7, and Hungarian Red were applied to these tiles and the developed fingermarks were compared using a numerical score system. Zar-Pro™ strips were applied to chemically treated and untreated bloodmarks alike. OPD proved to be effective at developing bloodmarks aged up to 90 days, including latent marks. Despite this capability, OPD did not perform as well as Acid Yellow 7 and so the continued use of Acid Yellow 7 is recommended. Zar-Pro™ strips were able to lift bloodmarks aged up to 90days as well as those chemically treated with either: OPD, Hungarian Red, Acid Yellow 7, or Amido Black although ridge detail was poor. Additional investigation into the capabilities of Zar-Pro™ strips for this purpose is recommended., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The benzazole scaffolds are present in various therapeutic agents and have been recognized as the essential pharmacophore for diverse biological activities. These have generated interest and necessity to develop efficient synthetic methods of these privileged classes of compounds to generate new therapeutic leads for various diseases. The biological activities of the benzazoles and efforts towards their synthesis have been summarized in a few review articles. In view of these, the aim of this review is to provide an account of the developments that have taken place in the synthesis of biorelevant benzazoles under microwave irradiation as the application of microwave heating has long been recognized as a green chemistry tool for speedy generation of synthetic targets. Attention has been focused to those literature reports wherein the use of microwave irradiation is the key step in the formation of the heterocyclic ring system or in functionalization of the benzazole ring system to generate the essential pharmacophoric feature. The convenient and economic way to synthesize these privileged class of heterocycles through the use of microwave irradiation that would be beneficial for the drug discovery scientist to synthesize biologically active benzazoles and provide access to wide range of reactions for the synthesis of benzazoles constitute the theme of this review. Examples have been drawn wherein the use of microwave heating offers distinct advantage in terms of improved product yields and reduction of reaction time as compared to those observed for the synthesis under conventional heating., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Lymphatic filariasis, a global cause of morbidity needs much more attention in developing potent therapeutics that can be effective against both microfilariae (mf) and adults. Efficient botanicals that can induce apoptosis of filarial parasites possibly can provide a direction towards developing new class of antifilarials. In this work we have evaluated the antifilarial efficacy of an optimized polyphenol rich ethanolic extract of Azadirachta indica leaves (EEA). A. indica A. Juss has been widely used in the traditional Indian medicinal system 'Ayurveda' for the treatment of a variety of ailments. A thorough investigation towards biochemical and molecular mechanisms describing ROS mediated apoptosis in Setaria cervi was performed. Motility reduction, MTT reduction assay and dye exclusion test have confirmed the micro- and macrofilaricidal potential of EEA. Alterations were visible in mf and trichrome stained section of EEA-treated adult worms. We have found cellular disturbances in EEA-treated parasites characterized by chromatin condensation, in situ DNA fragmentation and nucleosomal DNA laddering. Depletion in worm GSH level and elevation in parasite GST, SOD, catalase, GPx and superoxide anion indicated the generation of ROS. Our results provided experimental evidence supporting that EEA causes a decreased expression of anti-apoptotic genes and increased pro-apoptotic gene expression at the level of both transcription and translation. Here we are reporting for the first time that antifilarial activity of EEA is mediated by ROS up regulation and apoptosis., (Copyright © 2013 Elsevier Inc. All rights reserved.)