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Showing papers in "Journal of analytical and bioanalytical techniques in 2013"


Journal ArticleDOI
TL;DR: The results revealed that CTAB-modified bentonite demonstrated high adsorption capacities toward acid dyes, while bentonite exhibited sorption capacities lower than CTABs modified bentonite (CTAB-MBn) as discussed by the authors.
Abstract: Adsorption of Congo red (CR) from water via batch adsorption experiments onto bentonite and CTAB-modified bentonite (CTAB-MBn) was investigated. Studies concerning the factors influencing the adsorption capacities of bentonite and CTAB-MBn, such as initial dye concentration, adsorbent dosage, pH, ionic strength, contact time and temperature were systematically investigated and discussed. The results revealed that CTAB-modified bentonite demonstrated high adsorption capacities toward acid dyes, while bentonite exhibited sorption capacities lower than CTAB-MBn. The kinetics data were analyzed using first order and pseudo-second order models. It was best described by the pseudo-second order model. The isotherm data were investigated accord¬ing to Langmuir and Freundlich equations. Thermodynamic parameters ΔG°, ΔH° and ΔS° were calculated for the adsorption of CR on bentonite and CTAB-MBn ; the value of ΔG° showed the spontaneous nature of adsorption for both sorbents.

61 citations


Journal ArticleDOI
TL;DR: In this paper, a linear correlation between the percent reflectance at 980 nm and hematocrit was found, with a correlation coefficient (r) of 0.9933.
Abstract: One of the biggest concerns with quantitative analysis of dried blood spots (DBS) is the uncertainty related to sample volume from a predefined punch. Blood with a high hematocrit will not diffuse as far as blood with a lower hematocrit when spotted on filter paper, resulting in differences in sample volume per unit area. Quantifying the hematocrit of blood would allow for correction of the sample volume, improving the quantitation in DBS analyses. Therefore, we have developed a novel approach using reflectance to measure hematocrit that will allow for sample volume correction. DBSs prepared at various levels of hematocrit from 25% to 75% were analyzed by UV-visible reflectance from 210 nm to 1000 nm using an Ocean Optics reflectance fiber optic probe. A linear correlation between the percent reflectance at 980 nm and hematocrit was found, with a correlation coefficient (r) of 0.9933. Quantitative analysis of sample volume was conducted by fortification of samples with known concentrations of acylcarnitines (Free carnitine, C2, C3, C4, C5, C6, C8, C10, C12, C14, C16 and C18). Analysis was carried out using LC/MS/MS on a Waters Premier triple quadrupole mass spectrometer. Hematocrit and sample volume showed a linear relationship with a correlation coefficient (r) of 0.9929. We validated our model using donor samples at various levels of hematocrit by first analyzing the samples by NIR reflectance to determine hematocrit and then correcting for sample volume. Our results showed improved quantitation of various donor samples with accuracies between 81% and 115% compared to not correcting for sample volume, which showed accuracies from 67% to 136%. This is the first on-card approach used to determine sample hematocrit allowing for improved quantitation by correcting sample volume. In addition, the reflectance format used allows for direct, automatable volume corrections on the card, without the need for off-line procedures to test whole blood.

34 citations


Journal ArticleDOI
TL;DR: A simple spectrophotometric method based-uricase enzyme for the detection of uric acid in normal urine and gout patient's urine samples has been developed based on the reaction of hydrogen peroxide (H2O2) with yellow color of 4-Aminodiphenylamine Diazonium Sulfate (variamine blue RT salt) to yield a pale yellow-green coloured solution as mentioned in this paper.
Abstract: A simple spectrophotometric method based-uricase enzyme for the detection of uric acid in normal urine and gout patient’s urine samples has been developed based on the reaction of hydrogen peroxide (H2O2) with yellow color of 4-Aminodiphenylamine Diazonium Sulfate (variamine blue RT salt) to yield a pale yellow-green coloured solution. The absorbance of products as the output of enzymatic reaction and variamine blue RT salt were detected using uv-visible spectrophotometer with maximum absorbance at 269 nm. The response time of this proposed method was 20 minutes. The optimum pH activity on enzymatic and variamine blue RT salt reactions was foud to be pH 9. The relative standard deviation (RSD) of the reproducibility of this method was very good at 0.7%. The calibration plot of different concentrations of uric acid was found to be between 0.5-13 mM with a detection limit of 0.58 mM. The kinetic parameters the Michaelis-Menten constant (KM) and the maximum abosrbance (Absmax) in the presence of different concentrations of uric acid were evaluated using the Linewaver-Burk and Hofstee plots respectively. The enzymatic-spectrophotometric method was compared with established clinicalmethod and satisfactory agreement was achieved.

23 citations


Journal ArticleDOI
TL;DR: Zinc oxide (ZnO) nanostructures have attracted much interest for intracellular electrochemical measurements because of its large surface area, and its biocompatible properties as discussed by the authors.
Abstract: Zinc oxide (ZnO) nanostructures have attracted much interest for intracellular electrochemical measurements because of its large surface area, and its biocompatible properties. To design intracellu ...

19 citations


Journal ArticleDOI
TL;DR: The main aim of as discussed by the authors is chromatographic analysis of red pigment in different well known and local brands of lipsticks, which can be used as unique feature to distinguish among lipstick sources.
Abstract: The main aim of present work is chromatographic analysis of red pigment in different well known and local brands of lipsticks. Lipstick samples of different brands of similar color were selected for this study. Coloring agent was analyzed by thin layer chromatography (TLC). Using different solvent systems [Toluene/Benzene] (4:12), Toluene/Benzene/Cyclohexane (4:12:4), Toluene/Benzene/Diethyl ether (4:4). It is hypothesized that through thin layer chromatography analysis of the red pigment in these different brands will provide no characteristic data to distinguish among lipstick sources. There is no significant difference in the hRf values among the local and well known brands of lipsticks which can be used as unique feature.

18 citations


Journal ArticleDOI
TL;DR: A simple, precise, rapid, selective, and economic reversed phase high-performance liquid chromatography (RPHPLC) method has been established for simultaneous analysis of PRG and MC.
Abstract: A simple, precise, rapid, selective, and economic reversed phase high-performance liquid chromatography (RPHPLC) method has been established for simultaneous analysis of PRG and MC. A Phenomenex C18 (250×4.6 mm i.d) chromatographic column equilibrated with mobile phase water: methanol (60:40 v/v) adjusted to pH 6.5 with Triethylamine (1% v/v) was used. Mobile phase flow rate was maintained at 1 ml/min and effluents were monitored at 218 nm. The sample was injected using a 20 μl fixed loop, and the total run time was 10 min. Experimental conditions such as pH of mobile phase, column saturation time, selection of wavelength, etc. were critically studied and the optimum conditions were selected. The calibration curve 50-300 μg/ml for PRG and 0.5-2.0 μg/ml for MC. The limit of quantification was 24.10 μg/ml for PRG and 0.40 μg/ml for MC respectively. This HPLC procedure is economic, sensitive, and less time consuming than other chromatographic procedures. It is an importance tool for analysis of combined dosage form.

17 citations


Journal ArticleDOI
TL;DR: In this article, the structure interpretation of different organic compounds by different NMR techniques has been discussed, including 1D, 2D, and 3D-NMR, and Multi Dimensional NMR (Homonuclear and Heteronuclear).
Abstract: For the last fifty years nuclear magnetic resonance spectroscopy, generally referred as NMR, is one of the most versatile techniques for elucidation of structure of organic compounds. Among all available spectrometric methods, NMR is the only technique which offers a complete analysis and interpretation of the entire spectrum. Due to improved experimental technology and novel approaches, over the last decade nuclear magnetic resonance (NMR) has shown a tremendous progress. Generally, NMR spectroscopy makes use of three approaches; those are one dimension (1D), two dimensions (2D) and three dimensions (3D). Usually, the first approach of 1D-NMR ( 1H DEPT, 13 C, 15 N, 19 F, 31 P, etc.) generates good information about the structure of simple organic compounds, but in case of larger molecules the 1D-NMR spectra are generally overcrowded. Hence, the second approach of 2D-NMR (COSY, DQFCOSY, MQFCOSY, HETCOR, HSQC, HMQC, HMBC, TOCSY, NOESY, EXSY, etc.) is used for the further larger molecules, but 2D-NMR spectra also becomes complex and overlapping when used for further very large molecules like proteins. Hence, so as to achieve high resolution and reduced overlapping in spectra of very large molecules, Multi Dimensional-NMR (Homonuclear and Heteronuclear) are generally used. This paper supports interpretation of structure of different organic compounds by different NMR techniques.

15 citations


Journal ArticleDOI
TL;DR: In this article, the integration of photodynamic therapy (PDT) in a stage related treatment concept was presented and 10/12 cases in which PDT application was beneficial for achieving mucosal healing of BRONJ lesions.
Abstract: Introduction: Even though surgical intervention is the preferred option in treatment of Bisphosphonate-related Osteonecrosis of the Jaws (BRONJ) the application of low-level-laser therapy (LLLT) has been described either as part of conservative protocols or as adjuvant measure in surgical regimes. So far there are no reports concerning adjuvant photodynamic laser application in this indication in the literature. Case series: We present the integration of Photodynamic Therapy (PDT) in a stage related treatment concept and report 10/12 cases in which PDT application was beneficial for achieving mucosal healing of BRONJ lesions. Discussion and conclusion: In treatment of bisphosphonate-related osteonecrosis conservative therapeutic measures like the application of low-level-laser therapy and photodynamic therapy help to manage symptoms or may even promote mucosal healing. They are particularly helpful if surgical procedures are not indicated. Photodynamic therapy additionally provides antimicrobial effects and can therefore be used if complications in postoperative healing occur.

14 citations


Journal ArticleDOI
TL;DR: In this article, a simple, precise, rapid, selective, and economic reversed phase high-performance liquid chromatography (RPHPLC) method has been established for estimation analysis of DRO.
Abstract: A simple, precise, rapid, selective, and economic reversed phase high-performance liquid chromatography (RPHPLC) method has been established for estimation analysis of DRO. A Brownlee ODS C-18 column (250×4.6 mm i.d) chromatographic column equilibrated with mobile phase methanol-0.02 M KH2PO4 (80:20, v/v) (Final pH adjusted to 4 using Orthophosphoric acid) was used. Mobile phase flow rate was maintained at 1 ml/min and effluents were monitored at 289 nm. The sample was injected using a 20 μl fixed loop, and the total run time was 10 min. Experimental conditions such as pH of mobile phase, column saturation time, selection of wavelength, etc. were critically studied and the optimum conditions were selected. In RP-HPLC linear range was found to be 5-15 μg/ml and, mean recovery was found to be 99.99-100.03% and Rt of dronedarone was found to be 4.7 min. Degradation in acid, base, peroxide and thermal was found in range 8-20%. This stability indicating HPLC method is economic, sensitive, and less time consuming than other chromatographic procedures. It is a user-friendly and importance tool for analysis of dronedarone in tablet dosage forms.

14 citations


Journal ArticleDOI
TL;DR: The results of these experiments show that SpLAG-anti-IgY-HRP conjugate, a novel reagent, was the most versatile product among NSC and commercially-available conjugates.
Abstract: The aim of this study was to create universal chimeric conjugates able to react with both avian and mammalian immunoglobulins to be used as a reagent in Enzyme-linked Immunosorbent Assays (ELISAs). The periodate method was used in the conjugation process of linking horseradish peroxidase to immunoglobulin-binding bacterial proteins. ELISAs were used to prove the efficacy of the conjugates, namely newly synthesize conjugates (NSC) in the detection of immunoglobulins. All NSC bound to mammalian immunoglobulins, but failed to bind avian immunoglobulin Y (IgY), with the exception of the SpLAG-anti-IgY-HRP that was the most versatile binding to the all panel of purified immunoglobulin and sera. In conclusion, the results of these experiments show that SpLAG-anti-IgY-HRP conjugate, a novel reagent, was the most versatile product among NSC and commercially-available conjugates.

13 citations


Journal ArticleDOI
TL;DR: In this paper, TLC densitometric method for quantification of gallic acid, quercetin and lupeol using HPTLC has been developed, which can also be used for the estimation of these compounds in other herbal preparations and may be useful for standardization purposes.
Abstract: Objective: TLC densitometric method for quantification of gallic acid, quercetin and lupeol using HPTLC is developed. This is the first report of quantification of these three bioactive compounds viz. Gallic acid, quercetin and lupeol using HPTLC from this plant. Methodology: Quantification of gallic acid and quercetin was carried out from the methanolic extract using the solvent system of Toluene:Ethyl acetate:Formic acid (6:4:0.8 v/v/v). Lupeol was quantified from chloroform extract using the solvent system of Toluene:Ethyl acetate (7:3 v/v). Results: The Rf values of gallic acid, quercetin and lupeol are 0.22, 0.37 and 0.70 respectively. The linearity ranges for gallic acid (100 to 600 ng), quercetin (2000 to 7000 ng) and lupeol (100 to 1200 ng) with correlation coefficients (r-values) of 0.99968, 0.99708, and 0.99971 respectively. The amount of gallic acid, quercetin and lupeol was 124.31, 580.4, 24.89 μg/ml respectively. Conclusion: Quantification of gallic acid, quercetin and lupeol showed good resolution and separation from other constituents of extract. Its main advantages are its simplicity, accuracy, and selectivity. This method can also be used for the estimation of these compounds in other herbal preparations and may be useful for standardization purposes.

Journal ArticleDOI
TL;DR: P22 phage tail spike proteins have been immobilized on Si surfaces for optimized capture of host Salmonella enteric serovar Typhimurium and it was demonstrated that roughening of the Si surface before the TSP immobilization improves the bacterial capture 2-fold compared to a flat Si surface.
Abstract: Bacteriophage based technology has gained interest in developing pathogen detection platforms for biosensing applications. In this study, P22 phage tail spike proteins (TSPs) have been immobilized on Si surfaces for optimized capture of host Salmonella enteric serovar Typhimurium. It was then demonstrated that roughening of the Si surface before the TSP immobilization improves the bacterial capture 2-fold compared to a flat Si surface. Coarse, medium, fine and superfine size ridges were patterned on the Si surface using block copolymer layer and plasma etching and each surface was functionalized by TSPs for bacterial capture. The capture density increased with decreasing size of the ridge until it reached an optimum for fine ridges; the capture density decreased when the surface ridges were superfine and deep. This method shows a 22-fold and 3-fold increase in bacterial capture density compared to a Cys- and a His6-tag based oriented TSP immobilization, respectively. Bovine serum albumin (BSA) was used as a surface protective layer to prevent non-specific binding of bacteria and E. coli cells were used as control to demonstrate the specificity of recognition. Negligible binding was observed for control bacteria in presence of TSPs and the host bacteria in the absence of TSP on the surfaces.


Journal ArticleDOI
TL;DR: The present role and future possible improvements of ocular PDT are summarized and the use of PDT in the treatment of PCV is dramatically increasing.
Abstract: Photodynamic therapy (PDT) has represented an important treatment modality in many ocular disorders for more than a decade. The introduction of verteporfin-PDT to the treatment of neovascular age-related macular degeneration and polypoidal choroidal vasculopathy has rescued millions of patients from vision loss and blindness around the world. The most well-known vascular tumors in the eye treated with PDT include retinal capillary hemangioma, choroidal hemangioma, retinal vasoproliferative tumor or Wyburn-Mason syndrome. The discovery of the role of vascular endothelial cell growth factor in age-related macular degeneration and the revolution of its treatment by anti-vascular endothelial cell growth factor agents reduced the need for PDT in age-related macular degeneration; however, the use of PDT in the treatment of PCV is dramatically increasing. Furthermore, clinical results obtained with PDT, in combination with angiogenesis inhibitors, vascular disrupting agents, or/and anti-inflammatory compounds as adjuvant therapies, may well keep PDT as one the main treatment options. This review summarizes the present role and future possible improvements of ocular PDT.

Journal ArticleDOI
TL;DR: In this article, a variety of technologies for creation of sensors based on carbon nanotubes and their application in detecting of a numerous of biological molecules are discussed, and the authors underlined also the variety of technology for creating of sensors basing on carbon Nanotubes, which are often the principal element of electrochemical biosensors.
Abstract: Electrochemical biological sensor device unite the sensitivity of classic instrumental techniques with the inseparable selectivity of the biological agent. The bio-element of the sensing device identifies the analyte following in a biocatalytic way and definitely generates an electrical response recorded by a transducing element. The signal is proportional to concentration of the analyzed substance. Certain of developed modern biosensors are commercial available and are regularly applied in clinical, environmental, or industrial arrangements. The enzymatic electrode is often the principal element of electrochemical biosensors. The choice of suitable composition of agents, in example: biocatalyst, mediators, semiconducting elements, supports, for design of enzymatic sensors directs an electrode activity according to electron transport rate, its stability, and vitality. Presented article underlined also the variety of technologies for creation of sensors basing on carbon nanotubes and their application in detecting of a numerous of biological molecules.

Journal ArticleDOI
TL;DR: The dot-ELISA affinity test was optimized on Aβ peptide as antigen and anti-Aβ mAb and applied to a panel of eight anti-EpCAM mAbs which should be subsequently used for preparation of magnetic immunosorbent to capture circulating tumor cells (CTCs).
Abstract: Selecting the “right” monoclonal antibody (mAb) for an immunoaffinity-based application can be tricky, as many mAb producers offer a wide range of mAb clones against molecular structures of interest. Since there are significant differences in the quality of mAb clones, and particularly in their binding activity, an easy method for quick and low-cost comparison of various mAb clones was developed. The dot-ELISA affinity test is a simple, versatile and instrumentally no demanding technique, since it requires no expensive equipment (such as an ELISA reader or chemiluminescence/fluorescence imaging system) and can be performed in any biochemical laboratory. This method is based on a previously described dot-ELISA technique that is improved with a chaotropic step using different concentrations of ammonium thiocyanate in the range 0-2 M. In this work, the dot-ELISA affinity test was optimized on Aβ peptide as antigen and anti-Aβ mAb. Such protocol was then applied to a panel of eight anti-EpCAM (epithelial cell adhesion molecule) mAbs which should be subsequently used for preparation of magnetic immunosorbent to capture circulating tumor cells (CTCs).

Journal ArticleDOI
TL;DR: In this article, the authors review exciting trends in the development of synthetic reagents, fluidic integration, and mobile platforms that are necessary for ubiquitous point-of-care diagnostics.
Abstract: Biosensing technology is not currently capable of widespread use outside of a laboratory environment due to significantly limitation in bioreceptor function and production, as well as in the overall size, weight, and cost of the sensing platform. However, as technology continues to advance, biosensors could truly become ubiquitous, employing social media and personal electronic devices for mundane yet powerful capabilities. In the near future, point-of-care diagnostics in third-world countries could save millions of lives and revolutionize the healthcare industry worldwide. Recent trends show many of the traditional barriers to realizing this vision will soon be overcome. In this paper we review exciting trends in the development of synthetic reagents, fluidic integration, and mobile platforms that are necessary for ubiquitous biosensing capabilities.

Journal ArticleDOI
TL;DR: In lungs of infected mice, the influenza virus structural nucleoprotein NP was detected in parallel using a specific anti-NP antibody and a SPR technology, suggesting that applied sensor chip technology may be amenable to an arrow immunosensor for simultaneous detection of all known influenza virus proteins in infected tissues and cells.
Abstract: The detection and evaluation of concentration of influenza virus proteins in biological samples is critical in a broad range of medical and biological investigations regarding the concern over potential outbreaks of virulent influenza strains in animals and humans. This paper describes a sensitive, label-free approach for the detection of a virulence factor PB1-F2. PB1-F2 is a small, 90 amino acid long polypeptide expressed in influenza A viruses, which generally exacerbate virus pathogenicity. The developed immunosensoris based on a non-the-chipcovalently immobilized specific monoclonal anti-PB1-F2 antibody and a SPR technology. The immunosensor was calibrated using purified full length PB1-F2 protein. Itdetected PB1-F2 with the linear range extended from 10 to 500 nM, repeatability of 5% for 500 nM PB1-F2 and showed saturationof protein concentrations higher than 1 μM. The sensor can quantify PB1-F2 in its monomeric form but not when its oligomerization was induced by preincubation in 0.05% SDS. The immunosensor was successfully applied in the detection and quantification of PB1-F2 in infected mouse lungs and cell lines, providing temporal expression profiles of PB1-F2 during viral infection. In lungs of infected mice, the influenza virus structural nucleoprotein NP was detected in parallel using a specific anti-NP antibody. This parallel detection of PB1-F2 and NP suggests that applied sensor chip technology may be amenable to an arrow immunosensor for simultaneous detection of all known influenza virus proteins in infected tissues and cells.

Journal ArticleDOI
TL;DR: Similarities and differences in the metabolism of glyburide confirm the role of cytochrome P450 (CYP 45) enzymes and its distinct activity across the species.
Abstract: Studies were conducted on the Metabolism of sulfonylurea drug glyburide (5-chloro-N-(4-[N-(cyclohexylcarbamoyl) sulfamoyl] phenethyl)-2-methoxybenzamide) in human, mouse, rat, dog and monkey hepatic microsomes. Liquid chromatography with Diode array detector (LC-DAD) hyphenated with Q-Trap-Mass Spectrometer (Q-TRAP-MS/ MS) was employed to study the metabolism of glyburide in different species. The primary objective of the present study is to identify the similarities and differences in the metabolism of glyburide and to confirm the recent newly identified metabolites across the species. Results obtained from LC-UV and LC-MS/MS confirm the similarities and differences in the biotransformation of glyburide across the species. LC-UV-MS/MS data clearly suggests that the quantities of metabolites formed in all the species are dissimilar. Drug metabolite ratio is also different in all the species considered for tests. Mono-oxygenated metabolites and a metabolite due to the ring loss were identified in all the species. Similarities and differences in the metabolism of glyburide confirm the role of cytochrome P450 (CYP 45) enzymes and its distinct activity across the species.

Journal ArticleDOI
TL;DR: An accurate, sensitive, precise, rapid and isocratic Reversed-Phase HPLC (RP-HPLC) method for simultaneous estimation of Ipratropium bromide and Levosalbutamol in the bulk drug and in the pharmaceutical metered dose inhalers has been developed and validated as discussed by the authors.
Abstract: An accurate, sensitive, precise, rapid and isocratic Reversed-Phase HPLC, (RP-HPLC) method for simultaneous estimation of Ipratropium bromide and Levosalbutamol in the bulk drug and in the pharmaceutical metered dose inhalers has been developed and validated. The best separation was achieved on a 250 mm × 4.6 mm i.d., 5 μm particle, Inertsil ODS 3V-RP C18 column with Acetonitrile as the organic modifier and Di-Potassium Hydrogen Phosphate [0.03M] in water with pH 3.2 adjusted with Ortho-Phosphoric Acid (0.1% v/v) in the proportion of [30:70 v/v] as mobile phase at a flow rate of 0.8 mL min-1. UV detection was at 242 nm. Retention times were found to be 5.206 min. for Ipratropium bromide and 7.016 min. for Levosalbutamol.The response was a linear function of concentration over the range of 2.00 to 6.00 μg/ml, and 5.00 to 15.00 μg/ml respectively with correlation coefficient of 1.000 for Ipratropium Bromide and 0.994 for Levosalbutamol respectively. The percentage assay of Ipratropium Bromide and Levosalbutamol were found to be 99.87 %, and 101.42 % respectively. The Limit of Detection (LOD) for Ipratropium bromide and Levosalbutamol were found to be 1.27 μg/ml and 4.41μg/ml respectively. The Limit of Quantification (LOQ) for Ipratropium bromide and Levosalbutamol were found to be 3.81μg/ml and 13.23μg/ml respectively. The excipients present in the formulation were not interfered with the assay. The method is suitable for application in quality-control laboratories, because it is simple and rapid with good accuracy and precision.

Journal ArticleDOI
TL;DR: In this paper, the effect of ion suppression on the accuracy of liquid chromatography/ tandem mass spectrometry (LC-MS/MS) measurements was studied using Cremophor EL (CrEL).
Abstract: Ion suppression effect of dosing vehicle excipient Cremophor EL (CrEL) on the accuracy of liquid chromatography/ tandem mass spectrometry (LC-MS/MS) measurements was studied. Ion suppression cause significant errors in accuracy of the measured concentrations of test compounds, thereby invalidating the assessment of pharmacokinetic results. Using CrEL as a probe compound, the concentration-time profile of the excipient in plasma from rats dosed both orally and intravenously was determined. The most abundant molecular ions corresponding to PEG oligomers at m/z 828, 872, 916 and 960 with daughter ion at m/z 89 were selected for multiple reaction monitoring (MRM) in electrospray mode of ionization. Plasma concentrations of CrEL ranging from 0.50-1.0 mg/mL in the initial sampling points caused 2-10 fold ion suppression on most of the analytes studied. This can result in false rejection of compounds in a drug discovery screen. In this paper, various sample preparation methods, enhanced chromatographic selectivity, and alternative ionization methods were investigated as means to avoid or minimize ion suppression effects. The elimination of ion suppression effects was achieved by Liquid-Liquid Extraction (LLE) with hexane, TBME in Electrospray Ionisation (ESI) mode as sample preparation method. In contrast to ESI mode that had severe suppression effects from CrEL, atmospheric pressure chemical ionisation (APCI) mode is totally free of suppression effects. The mechanism of ion suppression caused by CrEL in relation to both liquid and gas phase reactions was discussed.

Journal ArticleDOI
TL;DR: Researchers maintain their efforts to determine specific markers of virulence and to evaluate the potential of emerging strains to cause new pandemics.
Abstract: Influenza A viruses (IAV) remain a major cause of respiratory disease worldwide each year and have been responsible for three main pandemics during the last century comprising the Spanish flu which killed up to 50 million of people. IAV are RNA enveloped viruses belonging to the Orthomyxoviridae family. The nature of the genome of IAV favors the constant and hardly predictable emergence of new strains such as highly virulent H5N1 viruses since 2003, or the H1N1 2009 pandemic strain. Recently, new human cases of severe respiratory illness with a new avian influenza A (H7N9) virus have been reported in China (mortality rate of 60%).Thus, researchers maintain their efforts to determine specific markers of virulence and to evaluate the potential of emerging strains to cause new pandemics.

Journal ArticleDOI
TL;DR: Protein damage photosensitized by DDP(V)TPP was inhibited by the addition of sodium azide and enhanced in deuterium oxide, indicating the contribution of singlet oxygen, and sodium azides could not completely inhibit the damage of human serum albumin, suggesting that the electron transfer mechanism contributes to protein damage as does singletoxy generation.
Abstract: For the fundamental study of photodynamic therapy, protein-damaging activity of the water-soluble phosphorus(V) porphyrin (DDP(V)TPP) was examined. Absorption spectrum measurement demonstrated the binding interaction between DDP(V)TPP and human serum albumin, a water-soluble protein. Photo-irradiated DDP(V)TPP damaged the amino acid residue of human serum albumin, resulting in the decrease of fluorescence intensity from the tryptophan residue of human serum albumin. Protein damage photosensitized by DDP(V)TPP was inhibited by the addition of sodium azide and enhanced in deuterium oxide, indicating the contribution of singlet oxygen. However, sodium azide could not completely inhibit the damage of human serum albumin, suggesting that the electron transfer mechanism contributes to protein damage as does singlet oxygen generation. Isolated tryptophan was also damaged by a photosensitization of DDP(V)TPP in solution, whereas DDP(V)TPP did not induce photodamage to tyrosine and phenylalanine. Using the application of a fluorometry of hydrogen peroxide, the deactivation of catalase photosensitized by DDP(V)TPP was demonstrated.

Journal ArticleDOI
TL;DR: In this article, a rapid sensitive and selective pseudo MRM based method for the determination of Cremophor EL (CrEL) in rat plasma was developed using Liquid chromatography/Tandem mass spectrometry (LC-MS/MS).
Abstract: A rapid sensitive, and selective pseudo MRM based method for the determination of Cremophor EL (CrEL) in rat plasma was developed using Liquid chromatography/Tandem mass spectrometry (LC-MS/MS). The analytes were detected using atmospheric pressure chemical ionization (APCI) tandem mass spectrometry. Plasma concentrations of CrEL were quantified after administration through oral and intravenous routes in male sprague dawley rats at a dose of 0.26 g/kg. The standard curve was linear (0.9982) over the concentration range of 2.10 to 2100.00 μg/mL. The lower limit of quantitation for CrEL was 2.10 μg/mL using 50 μL plasma. The coefficient of variation and relative error for inter and intra assay at three QC levels were 1.23 to 8.87 and -12.08 to 4.10 respectively. CrEL has poor oral bioavailability with mean absolute bioavailability of 2.32%. CrEL plasma concentration profiles after oral and intravenous dosing were without spiky concentration levels. Spiky plasma concentration profiles for new chemical entities (NCEs) are a common phenomenon in drug discovery, which could be due to entrohepatic circulation, sample handling errors. A novel proposal was conveyed to the scientific community, where formulation vehicle can be analysed as qualifier in the analysis of NCEs to address the spiky profiles.


Journal ArticleDOI
TL;DR: The principle of PDT relies on the administration of the PS, followed by the irradiation of the diseased area with light of appropriate wavelength, leading to the selective destruction of neoplastic cells.
Abstract: The principle of PDT relies on the administration of the PS, followed by the irradiation of the diseased area with light of appropriate wavelength. In the presence of molecular oxygen, highly cytotoxic reactive oxygen species (ROS) are generated, leading to the selective destruction of neoplastic cells (Figure 1). Specifically, once the PS has absorbed a photon, an electron is promoted from the ground state (S0) to an electronically excited state (S1). This short-lived specie can release its energy by emitting light (fluorescence), by internal conversion to heat or undergoing intersystem crossing to form a more stable triplet state (T1). The relatively long lifetime of the triplet state allows the interaction of the excited PS with the surrounding molecules, performing two classes of reactions, defined as Type I and Type II mechanisms. In the Type I pathway, the PS reacts directly with a substrate, transferring an hydrogen atom or an electron to form radical species. These free radicals further react with molecular oxygen, leading to ROS such as superoxide, peroxide or hydroxyl radicals. Alternatively, the Type II pathway is initiated by the energy transfer between the triplet excited state of the PS and nearby oxygen molecules, generating the singlet excited state of oxygen, referred as singlet oxygen, O2 (Figure 2). Both mechanisms can produce the photo-oxidation of certain amino acids residues in proteins, pyrimidine and purine bases of DNA/ RNA and unsaturated lipids. This process causes DNA damage and/or cytoplasmic membrane damage, allowing leakage of cellular contents or inactivation of membrane transport systems and, thus, triggering final cell death [4]. While it is generally accepted that O2 plays a key role in primary photodynamic effects, ROS generated by Type I mechanism become more important at low oxygen concentrations [5].

Journal ArticleDOI
TL;DR: A simple, precise, rapid, selective, and economic high-performance thin layer chromatography (HPTLC) method has been established for estimation analysis of BAL and is a user-friendly and importance tool for analysis of tablet dosage forms.
Abstract: A simple, precise, rapid, selective, and economic high-performance thin layer chromatography (HPTLC) method has been established for estimation analysis of BAL. HPTLC method was developed using Chloroform: methanol (3.5:2, v/v) as a Mobile Phase and Pre-coated silica gel G60–F254 aluminum sheet as a SP. Detection wavelength was 361 nm. In HPTLC linear range was 500-3000 ng/band, mean recoveries were found to be 99.99-100.04% & Rf of a BAL was found to be 0.61. This HPTLC method is economic, sensitive, and less time consuming than other chromatographic procedures. It is a user-friendly and importance tool for analysis of tablet dosage forms.

Journal ArticleDOI
TL;DR: A receptor-based biosensor, based on the reversible interaction between a blocked macromolecule and soluble ligands, and with major advantages such as the rapidity, the reusability of the capturing surface and the low cost per single test, could represent a promising approach for the diagnosis of SSc and other diseases characterized by anti-receptor autoantibodies or other bioactive ligands to cellular receptors.
Abstract: Biosensors are versatile tools for monitoring molecular interactions. Herein, we report a novel assay designed to detect anti-platelet-derived growth factor receptor α (PDGFRα) autoantibodies in the serum of patients affected by systemic sclerosis (SSc), an autoimmune disease of the connective tissue. The assay was based on resonant mirror sensing, and used recombinant PDGFRα as molecular "bait" for anti-PDGFRα autoantibodies (IgG class). The selection and optimization of the analytical procedure required a preliminary investigation on the preservation of the native-like conformation of the receptor following the immobilization procedure. The PDGFRα-based biosensor was used to test IgG purified from sera of SSc patients and healthy controls (HC). The specificity and the reversibility of the interaction permitted a rapid analysis, a single detection test requiring only a few minutes. Remarkably, this assay could discriminate between SSc patients and HC. This receptor-based biosensor, based on the reversible interaction between a blocked macromolecule and soluble ligands, and with major advantages such as the rapidity, the reusability of the capturing surface and the low cost per single test, could represent a promising approach for the diagnosis of SSc and other diseases characterized by anti-receptor autoantibodies or other bioactive ligands to cellular receptors.


Journal ArticleDOI
TL;DR: Microelectrodes coated with ZnO nanorods and immobilized glucose oxidase was used to determine glucose concentration in ASL of well-differentiated cultures of human airway epithelia and is an important step towards characterizing the physicochemical properties of ASL and understanding diseases caused by changes in AsL composition.
Abstract: The surface of the airways that conduct gases into and out of the lungs has components that are crucial in protecting the host from inhaled and aspirated pathogens. The thin (4-7µm height) layer of ...