Microcystins In Water Samples Research Articles

Determination of microcystins in environmental water samples with ionic liquid magnetic graphene

Microcystins is a class of monocyclic of heptapeptides with many different isomerides. It has become potential hazardous material in water environment for its toxic, distribution and stability. This project worked on a method for determination of trace microcystin (MC-LR and MC-RR) in environmental waters. The ionic liquid magnetic graphene (IL@MG) was prepared and applied to the concentration and determination of microcystins, based on magnetic solid phase extraction (MSPE), and coupled with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The ionic liquid magnetic graphene was prepared by coprecipitatial synthesis and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), specific surface area (BET), pore size distribution (BJH) and magnetic hysteresis loop. The experimental parameters of magnetic solid phase extraction, including amount of IL@MG, pH, extraction time and elution solvent were investigated by a univariate method and orthogonal screening. The method showed good linearity in the range of 0.01–10.0 g/L and 0.005–10.0 μg/L for MC-LR and MC-RR, when the pH of water samples was 4.00 and 10.0 mg adsorbents were used to extract targets for 18 min. The lowest detection limit was 0.414 ng/L and 0.216 ng/L for MC-LR and MC-RR respectively. The recoveries of the microcystins were in the range of 83.6–100.9%, and the relative standard deviation was less than 7.59%. The trace amount of MC-LR (0.020 μg/L) and MC-RR (0.003 μg/L and 0.021 μg/L) was detected in actural water samples. Attributed to its simple operator, low detection limit and high sensitivity, this method could be used for the detection of trace microcystins in water samples.

Микроцистины в литорали Куршского залива в 2017 г. по данным иммунохроматографического анализа

Присутствие гепатотоксичных цианотоксинов группы микроцистинов регистрируется в южной части Куршского залива ежегодно с 2010 г. Куршский залив имеет высокое рекреационное значение; национальный парк «Куршская коса» включён в список объектов Всемирного наследия ЮНЕСКО. Таким образом, потенциальная опасность для здоровья, обусловленная присутствием микроцистинов, ― неотъемлемая проблема этого района. Содержание микроцистинов в пробах воды из литоральной зоны определяли с помощью иммунохроматографических экспресс-тестов (Microcystin Strip Test, Abraxis Ltd). Пробы воды отбирали в мае ― ноябре 2017 г. дважды в месяц на шести прибрежных мониторинговых станциях. Впервые показано присутствие микроцистинов в летне-осенний период во всей литорали южной части Куршского залива в течение вегетационного периода. В мае микроцистины отсутствовали. Самые высокие значения (5–10 мкг·л-1) отмечены в конце июня и в сентябре на Куршской косе. За период наблюдений в 2017 г. микроцистины встречались реже и в меньших количествах, чем в 2011–2016 гг. В середине и конце октября микроцистины выявлены только дважды, на Куршской косе. На восточном и южном побережьях максимальное значение составляло 5 мкг·л-1 (отмечено один раз в конце сентября). В других пробах токсины не были обнаружены или их значения не превышали 2,5 мкг·л-1.

Determination of microcystins in water samples by deep eutectic solvent-based vortex-assisted liquid-liquid microextraction coupled with ultrahigh-performance liquid chromatography-high resolution mass spectrometry.

Rapid screening of two microcystins (i.e., microcystin-YR (MC-YR) and microcystin-LR (MC-LR)) in surface water samples was performed by a simple and eco-friendly procedure using deep eutectic solvent-based vortex-assisted liquid–liquid microextraction (DES-based VALLME) combined with ultrahigh-performance liquid chromatography and electrospray ionization (+)-quadrupole time-of-flight mass spectrometry (UHPLC-ESI(+)-qTOF-MS) detection. To obtain an efficient water-miscible DES, choline chloride and phenol at a molar ratio of 1 : 2 were used as an extractant for VALLME. To optimize factors of DES-based VALLME, response surface design alongside Box–Behnken design was used. The limits of quantitation (LOQs) were 0.5 ng mL−1 and 0.4 ng mL−1 for MC-YR and MC-LR, respectively, which is sensitive enough to meet the World Health Organization (WHO) maximum guideline level for MC-LR in water of 1.0 ng mL−1. Moreover, satisfactory precision with relative standard deviations (RSD) for both intra- and inter-day analysis lower than 11%, and trueness (also known as mean extraction recovery) ranged from 85.5 to 113% based on the ICH method validation guideline.

Magnetic γ-cyclodextrin polymer with compatible cavity promote the magnetic solid-phase extraction of microcystins in water samples

Microcystins (MCs), which are produced by eruptive cyanobacteria, seriously threaten the health of humans for their poisonousness. Herein, a facile strategy was introduced to synthesize the magnetic γ-cyclodextrin polymer (Fe3O4@PDA@γ-CDP) composite and set it as a novel adsorbent with excellent properties for the magnetic solid-phase extraction (MSPE) of MCs. The prepared Fe3O4@PDA@γ-CDP microspheres exhibit good aqueous dispersibility and highly affinity for MCs, thus contribute to an excellent extraction performance for trace MCs in water samples. Combined with HPLC–MS/MS, a handy, sensitive and efficient method was developed for detection of MCs in water samples, which shows good linearity (R2 ≥ 0.9992) in the range of 1.0–1000 pg mL−1, low limits of detection (0.8–2.0 pg mL−1, S/N = 3), satisfactory repeatability with the relative standard deviations (RSDs) lower than 6.2% (n = 5). At last, the proposed method was successfully applied for the extraction and detection of MCs in fresh water and sea water samples, which provides great potential of trace-level MCs determination in lake and sea water.

Analysis of microcystins using high-performance liquid chromatography and magnetic solid-phase extraction with silica-coated magnetite with cetylpyridinium chloride.

Microcystins (MCs), produced by freshwater cyanobacteria, can be serious water pollutants, so it is important to monitor their concentration in drinking water. We have developed a method for rapid and accurate determination of microcystin levels in environmental water, using magnetic solid-phase extraction and high-performance liquid chromatography with UV detection. The magnetic composite material, which was combined with cetylpyridinium chloride, was prepared by hydrothermal synthesis. The optimal extraction of microcystins in water sample was achieved by optimizing the amount of adsorbent, time of adsorption, ratio of eluting solvent, and volume of eluent. Under the optimal conditions, the limit of detection of MC-LR was 0.001μg/L, and the limit of quantification was 0.0028μg/L. The limit of detection of MC-RR was 0.001μg/L, and the limit of quantification was 0.003μg/L. These values are far lower than those established by the International Health Organization for the maximum concentration of microcystins in drinking water. The magnetic solid-phase extraction adsorbent used in this method has the advantages of simple preparation, low price, and easy solid-liquid separation, and it can be used for the rapid and sensitive monitoring of trace microcystins in environmental water samples.

Extending electronic tongue calibration lifetime through mathematical drift correction: Case study of microcystin toxicity analysis in waters

There are certain issues in e-tongue research which precludes wide adoption of these systems in routine analytical practice. An important problem relates to sensor readings’ drift which may invalidate corresponding multivariate calibration. Invalidation of established multivariate classification and regression models during a certain period of time leads to necessity of frequent e-tongue system recalibration requiring significant investment of time and efforts. An alternative approach can be based on mathematical sensor drift correction using sensor responses in certain standard solutions which are measured with required periodicity. In this study we show that application of univariate single sensor standardization approach (similar to single wavelength standardization suggested in spectroscopy) can significantly improve precision of both regression and classification models and can extend a calibration lifetime up to the period of over two months compared with two weeks for raw uncorrected data. As a case study analysis of microcystins in water samples with potentiometric e-tongue was addressed in two aspects: quantitative microcystins concentration evaluation and classification of samples into toxic and non-toxic ones.

Characterization of cyanobacterial toxins in Lake Naivasha, Kenya

Microcystins are a class of cyanobacterial toxins largely found in water and are often responsible for poisoning animals as well as humans. A more recent scenario is the poisoning of domestic water supply system in Toledo (Ohio), USA. Consequently, water supply to the city had to be suspended for weeks in order for authorities to ascertain the commodity's safety before restoring supply. In Kenya, there have been very few studies on cyanotoxins and their adverse health effects in spite of the fact that cyanobacteria have been implicated in several poisoning episodes of humans and animals worldwide, occasioned by drinking of microcystin contaminated water. This paper therefore, reports data on the first identification and characterization of hepatotoxic microcystins in water samples of Lake Naivasha. Samples from the lake were investigated over a modest period of three months. The phytoplankton community was mainly dominated by the cyanobacterium Microcystisaeruginosa. The colour of the water samples was found to be 520 ± 91 ptco, while the conductivity was 234 ± 0.8 μs/cm and the total dissolved solids was 1035 ± 12 mg/L. Due to the high turbidity (59.0 ± 24 ntu), phytoplankton biomass was low, ranging between 1.5 and 8.2 mg L−1. Using UV-Vis and HPLC techniques, the microcystin-LR and-RR were detected in all the water samples collected from the lake. HyperChem computational package was used to estimate the toxicity index of microcystin-RR based on the octanol-water partition coefficient and found to be 230 times more soluble in water than in octanol. Thus, microcyctin-RR is highly soluble in polar biological tissues which may result in cell injury, oxidative stress, and ultimately cancer. To the best of our knowledge, this is the first evidence of microcystins in Lake Naivasha.

Microcystins-LR, -YR and -RR in Six Bulgarian Water Bodies of Health and Conservational Importance (2012-2014)

This study presented the results of HPLC-DAD microcystin and nodularin analyses from five Bulgarian water bodies (reservoirs Stoudena, Pchelina and Bistritsa, and lakes Dourankoulak and Vaya) carried out in 2012-2014, as a continuation of our work from 2004 to 2005 and in 2011, and first data on microcystins in the lake Momin Brod were detected in the period 2012-2014. The total concentration of microcystins in water samples ranged from 0.1 to 1.8 μg/l and their amount in the concentrated biomasses from net samples ranged from 1.35 to 296 μg/g (d.w.). The presence of the most toxic microcystin-LR was recorded in all studied lakes and reservoirs, where also microcystins RR and YR were detected, but no microcystin-LA and nodularin were found.

Solid-phase extraction based on mesoporous Fe 3 O 4 @mSiO 2 @Cu 2+ magnetic nanoparticles coupled with high performance liquid chromatography for the determination of microcystins in water samples

Mesoporous magnetic nanoparticles of Fe3O4 @ mSiO2 @ Cu2+ were synthesized by two methods of hydrothermal synthesis and room temperature synthesis. The synthesized mesoporous Fe3O4 @ mSiO2 @ Cu2+ nanoparticles presented uniform sizes, good magnetic properties and specific selectivity. In this work, a novel magnetic solid-phase extraction (MSPE) method based on mesoporous Fe3O4 @ mSiO2 @ Cu2+ nanoparticles (NPs) coupled with high performance liquid chromatography (HPLC) was developed for the simultaneous extraction of trace amount of microcystin-LR (MC-LR) in water samples. The MSPE extraction conditions and HPLC conditions were optimized. The results showed that good linear relationship (r = 0.999 4) was obtained between peak area and mass concentration of MC-LR in the range of 0.1-15 µg/L. The limit of detection was 0.025 µg/L, and the limit of quantification was 0.082 µg/L. Furthermore, this method was used for the analysis of algal toxins in water samples with the recovery of 78%. The results indicated that Fe3O4 @ mSiO2 @ Cu2+ magnetic nanoparticles were good pretreatment alternatives for the concentration of microcystin-LR in water samples.

Total microcystins analysis in water using laser diode thermal desorption-atmospheric pressure chemical ionization-tandem mass spectrometry

A new approach for the analysis of the cyanobacterial microcystins (MCs) in environmental water matrices has been developed. It offers a cost efficient alternative method for the fast quantification of total MCs using mass spectrometry. This approach permits the quantification of total MCs concentrations without requiring any derivatization or the use of a suite of MCs standards. The oxidation product 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) was formed through a Lemieux oxidation and represented the total concentration of free and bound MCs in water samples. MMPB was analyzed using laser diode thermal desorption-atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). LDTD is a robust and reliable sample introduction method with ultra-fast analysis time (<15ssample−1). Several oxidation and LDTD parameters were optimized to improve recoveries and signal intensity. MCs oxidation recovery yield was 103%, showing a complete reaction. Internal calibration with standard addition was achieved with the use of 4-phenylbutyric acid (4-PB) as internal standard and showed good linearity (R2>0.999). Limits of detection and quantification were 0.2 and 0.9μgL−1, respectively. These values are comparable with the WHO (World Health Organization) guideline of 1μgL−1 for total microcystin-LR congener in drinking water. Accuracy and interday/intraday variation coefficients were below 15%. Matrix effect was determined with a recovery of 91%, showing no significant signal suppression. This work demonstrates the use of the LDTD-APCI-MS/MS interface for the screening, detection and quantification of total MCs in complex environmental matrices.

Production of a broad specificity antibody for the development and validation of an optical SPR screening method for free and intracellular microcystins and nodularin in cyanobacteria cultures

A highly sensitive broad specificity monoclonal antibody was produced and characterised for microcystin detection through the development of a rapid surface plasmon resonance (SPR) optical biosensor based immunoassay. The antibody displayed the following cross-reactivity: MC-LR 100%; MC-RR 108%; MC-YR 68%; MC-LA 69%; MC-LW 71%; MC-LF 68%; and Nodularin 94%. Microcystin-LR was covalently attached to a CM5 chip and with the monoclonal antibody was employed in a competitive 4 min injection assay to detect total microcystins in water samples below the WHO recommended limit (1 µg/L). A 'total microcystin' level was determined by measuring free and intracellular concentrations in cyanobacterial culture samples as this toxin is an endotoxin. Glass bead beating was used to lyse the cells as a rapid extraction procedure. This method was validated according to European Commission Decision 96/23/EC criteria. The method was proven to measure intracellular microcystin levels, the main source of the toxin, which often goes undetected by other analytical procedures and is advantageous in that it can be used for the monitoring of blooms to provide an early warning of toxicity. It was shown to be repeatable and reproducible, with recoveries from spiked samples ranging from 74 to 123%, and had % CVs below 10% for intra-assay analysis and 15% for inter-assay analysis. The detection capability of the assay was calculated as 0.5 ng/mL for extracellular toxins and 0.05 ng/mL for intracellular microcystins. A comparison of the SPR method with LC-MS/MS was achieved by testing six Microcystis aeruginosa cultures and this study yielded a correlation R(2) value of 0.9989.

New Records of Microcystins in Some Bulgarian Water Bodies of Health and Conservational Importance

Microcystins cause acute hepatotoxicity and chronic liver tumor promotion. This study presents the results of HPLC DAD analyses and their LC-MS confirmation of samples from five Bulgarian water bodies (reservoirs Stoudena, Pchelina, Bistritsa and lakes Dourankoulak, Vaya). The total concentration of microcystins in water samples ranged from 0.1 to 26.5 μg/l. The amount of microcystins in the biomasses ranged from 11.4 to 49.6 μg/g (d.w.). The high percent of positive samples in which the most toxic microcystin-LR is recorded, can serve as a strong alarm for the necessity of a serious study and relevant discussion of the problem with responsible authorities at national level.

Sensitive determination of total microcystins with GC-MS method by using methylchloroformate as a derivatizing reagent

Various microcystins (MCs) produced by cyanobacteria pose a potential threat to water resources, therefore, the determination of the total MCs rather than the content of some specific types of MCs in water is of great importance. Oxidation of MCs causes cleavage of the Adda moiety of microcystins to 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB). In this paper, a new method based on the derivatization of MMPB with methylchloroformate is proposed for the sensitive determination of total MCs. The oxidation conditions as well as the esterification process were optimized through a series of batch experiments. With the optimized procedure, a detection limit as low as 0.56 μg L−1 was achieved for total MCs and the method was successfully applied to the determination of MCs in real samples. A comparison study by using the LC-MS method for direct quantification of the MMPB was also conducted to validate the proposed method. The results proved that the technique is highly sensitive and convenient for the quantification of total MCs in water samples. As an additional feature, the method does not require the use of toxic and expensive standards of MCs in the environmental monitoring.

Optimization of Microcystin Extraction for Their Subsequent Analysis by HPLC-MS/MS Method in Urban Lake Water

This paper represents to propose an effective extraction procedure for traditional toxin determination techniques in urban lake. Efficiency of each extraction solvent as well as other key parameters affecting extraction efficiency including ultrasonication time and extraction pH were evaluated and optimized. The present study results indicated that 40% acidified methanol (pH~3) with sonication 15~20min has been shown to be a rapid and efficient method for the routine analysis of a wide range of microcystins in water samples. Our study also suggested that analytical method based on HPLC-MS/MS with SPE techniques provides a simplified enrichment procedure and rich information for both quantization and identification effective tool for analysis of urban landscape water quality. The development of this method may facilitate the understanding of the best extraction method for the routine analysis of microcystins in water bodies. Moreover, it may be valuable for purification scale.

Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide

A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440–540nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4–1.2μgL−1 and 1.4–3.9μgL−1, respectively. The method was validated at 0.1 and 1.0μgL−1 levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples.

Development and application of ultra performance liquid chromatography–electrospray ionization tandem triple quadrupole mass spectrometry for determination of seven microcystins in water samples

In the present work, an ultra performance liquid chromatography (UPLC)–electrospray ionization tandem triple quadrupole/mass spectrometry (ESI-MS/MS) method was developed in selected reaction monitoring (SRM) mode to determine the amounts of seven/microcystin variants (MCYST-RR, -YR, -LR, -LA, -LY, -LW, -LF) in water samples. Solid phase extraction (SPE) or porous filter was used for sample cleaning-up and analyte enrichment. A C18 column enabled separation of 7 microcystins within 10 min. Translation reaction ions including 995.6 > 134.9 (RR), 1045.8 > 135.1 (YR), 910.9 > 375.7 (LA), 1002.3 > 375.6 (LY), 520.1 > 135.0 (LR), 1025.8 > 891.7 (LW), 986.8 > 852.6 (LF) were set as quantitative ions and the enkephalin was the internal standard. Upon method validation, the limits of detection (LODs) and limits of quantification (LOQs) were found to be 0.06 μg L −1 and 0.2 μg L −1 (injection volume of 10 μL), respectively, for all seven microcystin variants. The correlation coefficients were larger than 0.994 in all linear ranges and recoveries were in the range of 66.24–99.22%. The developed approach was highly sensitive and easy to perform. It generated accurate quantitative results for the analysis of microcystins in environmental water samples with a wide concentration range. The results showed that MC-RR and MC-LR widely existed in polluted water, while MC-LA and MC-LY were detected sporadically.

Aptamers in Immunotherapy

Human Gene TherapyVol. 19, No. 5 ReviewsAptamers in ImmunotherapyClaudia M. Dollins, Smita Nair, and Bruce A. SullengerClaudia M. DollinsSearch for more papers by this author, Smita NairSearch for more papers by this author, and Bruce A. SullengerSearch for more papers by this authorPublished Online:28 May 2008https://doi.org/10.1089/hum.2008.045AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited ByChemical Modifications for a Next Generation of Nucleic Acid Aptamers29 April 2022 | ChemBioChem, Vol. 23, No. 15Generation and Selection of Specific Aptamers Targeting Brucella Species through an Enhanced Cell-SELEX Methodology30 May 2022 | International Journal of Molecular Sciences, Vol. 23, No. 11Visual detection of tropomyosin, a major shrimp allergenic protein using gold nanoparticles (AuNPs)-assisted colorimetric aptasensor12 February 2021 | Marine Life Science & Technology, Vol. 3, No. 3Recent Progress in Aptamer Discoveries and Modifications for Therapeutic Applications30 June 2020 | ACS Applied Materials & Interfaces, Vol. 13, No. 8Alternative Analyte-Binding Compounds for Immunosensor-Like Point-of-Care Application13 October 2020Aptamers for Thrombotic Diseases26 March 2021DNA aptamer-based rolling circle amplification product as a novel immunological adjuvant17 December 2020 | Scientific Reports, Vol. 10, No. 1A Homodimeric Aptamer Variant Generated from Ligand-Guided Selection Activates the T Cell Receptor Cluster of Differentiation 3 ComplexMolecular Therapy - Nucleic Acids, Vol. 22Biosensing of microcystins in water samples; recent advancesBiosensors and Bioelectronics, Vol. 165Inhibition of miR‐155 in MCF‐7 breast cancer cell line by gold nanoparticles functionalized with antagomir and AS1411 aptamer31 January 2020 | Journal of Cellular Physiology, Vol. 235, No. 10Ligand Guided Selection (LIGS) of Artificial Nucleic Acid Ligands against Cell Surface Targets2 December 2019 | ACS Applied Bio Materials, Vol. 3, No. 5HER2-Positive Breast Cancer Immunotherapy: A Focus on Vaccine Development9 January 2020 | Archivum Immunologiae et Therapiae Experimentalis, Vol. 68, No. 1 Aptamer Hybrid Nanocomplexes as Targeting Components for Antibiotic/Gene Delivery Systems and Diagnostics: A Review 1 June 2020 | International Journal of Nanomedicine, Vol. Volume 15A Bottom-Up Approach for Developing Aptasensors for Abused Drugs: Biosensors in Forensics1 October 2019 | Biosensors, Vol. 9, No. 4Aptamer Oligonucleotides as Potential Therapeutics in Hematologic DiseasesMini-Reviews in Medicinal Chemistry, Vol. 19, No. 10Dye Coupled Aptamer-Captured Enzyme Catalyzed Reaction for Detection of Pan Malaria and P. falciparum Species in Laboratory Settings and Instrument-Free Paper-Based Platform22 February 2019 | Analytical Chemistry, Vol. 91, No. 6DNA NanostructuresAdvances in the oligonucleotide-based sensor technology for detection of pharmaceutical contaminants in the environmentComplexes of DNA with fluorescent dyes are effective reagents for detection of autoimmune antibodies15 May 2017 | Scientific Reports, Vol. 7, No. 1Emerging Biorecognition and Transduction Schemes for Rapid Detection of Pathogenic Bacteria in Food11 September 2017 | Comprehensive Reviews in Food Science and Food Safety, Vol. 16, No. 6A Novel PD-L1-targeting Antagonistic DNA Aptamer With Antitumor EffectsMolecular Therapy - Nucleic Acids, Vol. 5Cancer immunotherapy via nucleic acid aptamersInternational Immunopharmacology, Vol. 29, No. 2Aptamer Oligonucleotides: Novel Potential Therapeutic Agents in Autoimmune Disease Weibin Li and Xiaopeng Lan20 July 2015 | Nucleic Acid Therapeutics, Vol. 25, No. 4Selection of HBsAg-Specific DNA Aptamers Based on Carboxylated Magnetic Nanoparticles and Their Application in the Rapid and Simple Detection of Hepatitis B Virus Infection19 May 2015 | ACS Applied Materials & Interfaces, Vol. 7, No. 21Development of Aptamer oligonucleotides as Anticoagulants and Antithrombotics for Cardiovascular Diseases: Current StatusThrombosis Research, Vol. 134, No. 4Aptamer-targeted Antigen DeliveryMolecular Therapy, Vol. 22, No. 7Functionalized DNA Nanostructures for Nanomedicine24 June 2013 | Israel Journal of Chemistry, Vol. 53, No. 8Electrochemical Analysis of Proteins31 October 2012Aptamer-Mediated Delivery of Splice-Switching Oligonucleotides to the Nuclei of Cancer Cells Jonathan W. 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Sullenger.Aptamers in Immunotherapy.Human Gene Therapy.May 2008.443-450.http://doi.org/10.1089/hum.2008.045Published in Volume: 19 Issue 5: May 28, 2008Online Ahead of Print:May 12, 2008PDF download

Study on Separation of Microcystins Using Polymethacrylate-Based Capillary Monolithic Column

Polymethacrylate-based monolithic column was prepared in 150 microm i. d. capillary column in situ using butylmethacrylate and ethylene dimethacrylate. The application of methacrylate monolithic column in capillary high performance liquid chromatography ( micro-HPLC) for separation of microcystins (MCs) with ultraviolet (UV) detection has been studied. The properties of the monolithic column could be easily tailored by altering the preparation conditions. For the good reproducibility in preparation of monolithic column, this method could be used for the analysis of samples in practical. The effects of composition of mobile phase, pH value, concentration of the buffer, and the flow rate of the mobile phase on the separation of microcystins were investigated. The optimum separation for microcystins, MC-LR, MC-YR, and MC-RR, was achieved with a gradient elution of mobile phase A (0. 01 mol/L phosphate buffer, pH 2. 5 ) and mobile phosphate B (acetonitrile). The standard microcystins could be baseline-separated within 9 min. The limits of detection (LODs) (S/N = 3) for three standard microcystins were in the range of 0. 80 - 1. 03 mg/L. The intra-day and inter-day precisions of the method were obtained with the values of relative standard deviation less than 1. 0% and 2. 0%, respectively. This method was successfully used to analyze bloom samples and laboratory-cultured samples of cyanobacteria after performing solid phase extraction (SPE) using C18 cartridges for preconcentration. The whole procedure provided low LODs for MCs, e. g. the LOD for MC-LR was found to be 420 ng/L. This family of microcystin is analyzed by VL-HPLC using methacrylate monolithic column for the first time. It is shown that this method is promising in the routine analysis of microcystins in water samples in practical.

Determination of trace amount of microcystins in water samples using liquid chromatography coupled with triple quadrupole mass spectrometry

Microcystins, a group of cyclic heptapeptide heaptoxins and tumor promoters, are bio-generated by cyanobacteria occurring in eutrophic lakes, rivers and reservoirs. In the present work, a novel liquid chromatography electrospray ionization (ESI-MS) tandem triple quadrupole mass spectrometry method was developed to determine the trace amounts of major microcystin variants in waters. Solid phase extraction (SPE) consuming 10 mL of water samples was used for sample cleaning-up and analyte enrichment. A reverse phase LC separation system consisting a symmetry 300 C-18 column (4.6 mm × 75 mm i.d., 3.5 μm, pore size 300 Å) and binary gradient methanol-water mobile phase was applied for the separation of microcystin variants (MC-RR, -LR, -LW and -LF). Formic acid was spiked into the mobile phase to enhance the ionization efficiency. Tandem MS/MS analysis was performed in multi-reaction monitoring mode (MRM). Product-ion traces at m/ z 519.9 → 135.0 for MC-RR, 498.4 → 135.0 for MC-LR, 1025.8 → 891.7 for MC-LW and 986.8 → 852.5 for MC-LF was used for quantification of the corresponding microcystin variants, and trace at m/ z 556.1 → 278.0 used for internal standard enkephalin. Limits of quantification (LOQs) were 0.16, 0.04, 2.0, 1.0 and 0.10 μg/L for MC-RR, MC-LR, MC-LW, MC-LF and enkephalin, respectively. Intra- and inter-day precisions for the determination of the four variants were better than 5 and 6% in relative standard deviations (R.S.D.s), and recoveries for the four variants were in the range of 95–105%. The developed approach has been applied for the determination of the trace amounts of miccocystins in water samples of Taihu Lake of eastern China. The results showed that MC-RR and MC-LR were major variants detected in the water samples, and their concentrations significantly increased with the season changing from Spring to Summer.

Use of protein phosphatase inhibition assay to detect microcystins in Donghu Lake and a fish pond in China

Seasonal variations in the level of total microcystins in water samples collected from Donghu Lake and a fish pond in Wuhan, China, were studied between March 1995 and February 1996 using a protein phosphatase inhibition assay involving a radioactive 32P-labelled substrate. The assay is highly reliable and repeatable, and is probably the most sensitive assay for microcystin detection to date. Results of the survey indicated the presence of microcystins in the water samples, and the concentration of microcystins appeared to be related to the degree of eutrophication and water temperature. There is also a correlative relationship between the quantity of microcystins and the abundance of microcystin-producing cyanobacteria ( Anabaena and Oscillatoria) in the water bodies over a year cycle. In the present study, the positive detection of microcystins in water bodies having no signs of algal bloom warns of considerable potential threat of these waters to public health.