Chitosan based Butyrylcholinesterase Biosensor for the Pesticide Detection

The increasing concern for ground water pollution, due to the use of pesticides in agriculture, requires a strong effort in order to detect pollutants with reliable, economical and rapid methods; some pollutants like pesticides and heavy metals, infact, are very dangerous for human health. Pesticides are highly toxic compounds and some of them are powerfull inhibitors of enzymes involved in nerve functions. It is true that they show low environmental persistence but they have acut toxicity and therefore, there is a demand for fast screening methods for low concentrations of these pollutants. Detection methods currently used (LC, GC-MS) are not suitable as rapid screening methods, as they are time consuming and provide only discontinuous analysis. In this study, our goal was to develop a rapid and cheaper method for pesticide analysis. It is based on the potentiometric determination of the inhibiting properties of the pesticides on the cholinesterase activity. The enzyme butyrylcholinesterase is immobilized on the surface of the pH-electrode by using chitosan membrane, then the measuring conditions (pH, temperature, ionic strenght) were optimized. On the other hand, organic phase stabilitiy of the enzyme electrode was also tested. A temperature of 25 oC and pH 8.5 were found to be optimum conditions. All measurements were carried out 2.5 mM borate buffer (pH 8.5) at 25 oC. Furthermore, dependence of enzyme inhibition of the pesticide concentration and the regeneration conditions of inhibitted enzyme were achieved

A Lipoxygenase Sensor for Essential Fatty Acid (EFA) Determination

The essential fatty acids (EFAs) are a group of 12 compounds, but linoleic acid and a-linolenic acid are the only EFAs which are found in the diet, particularly in vegetable oils, in some abundance. The other on EFAs are either metabolic products of linoleic and a-linolenic acids or are found in the diet especially in marine foods, considerebly smaller amounts. The steadily growing knowledge about the correlation between the fatty acid composition of the diet and clinical disorders leads to a growing demand for a rapid and easy to use analytical device for fatty acid determination in foods. Up to date, the fatty acid composition of fats and oils is determined mainly by gas chromatography (GC), although GC is well established in lipid analysis and offers high sensitivities, it is still time consuming and laborious . In this study, we describe the development of enzyme sensors for the determination of w-3 and w-6 fatty acis from the mixture of EFAs. Since linoleic and a-linolenic acids show differences in first and second oxygenation activities, it is possible to analyse each of them in EFAs mixture. Lipoxygenases in general catalyse the oxygenation of polyunsaturated fatty acids containing a cis, cis-1,4-pentadiene system by molecular oxygen. The oxygen consumption due to the lipoxygenase catalysed oxygenation of EFAs monitored amperometrically. Lipoxygenase was immobilized on the surface of oxygen electrode by using different membrane systems. Each systems were compared with regard to linear ranges of the calibration plots, sensitivities, detection limits. Furthermore, optimization of working conditions (pH, temperature etc.) and stability tests were also studied

Transferrin-Decorated Niosomes with Integrated InP/ZnS Quantum Dots and Magnetic Iron Oxide Nanoparticles: Dual Targeting and Imaging of Glioma

The development of multifunctional nanoscale systems that can mediate efficient tumor targeting, together with high cellular internalization, is crucial for the diagnosis of glioma. The combination of imaging agents into one platform provides dual imaging and allows further surface modification with targeting ligands for specific glioma detection. Herein, transferrin (Tf)-decorated niosomes with integrated magnetic iron oxide nanoparticles (MIONs) and quantum dots (QDs) were formulated (PEGNIO/QDs/MIONs/Tf) for efficient imaging of glioma, supported by magnetic and active targeting. Transmission electron microscopy confirmed the complete co-encapsulation of MIONs and QDs in the niosomes. Flow cytometry analysis demonstrated enhanced cellular uptake of the niosomal formulation by glioma cells. In vitro imaging studies showed that PEGNIO/QDs/MIONs/Tf produces an obvious negative-contrast enhancement effect on glioma cells by magnetic resonance imaging (MRI) and also improved fluorescence intensity under fluorescence microscopy. This novel platform represents the first niosome-based system which combines magnetic nanoparticles and QDs, and has application potential in dual-targeted imaging of glioma

Analytical techniques for multiplex analysis of protein biomarkers

Introduction: The importance of biomarkers for pharmaceutical drug development and clinical diagnostics is more significant than ever in the current shift toward personalized medicine. Biomarkers have taken a central position either as companion markers to support drug development and patient selection, or as indicators aiming to detect the earliest perturbations indicative of disease, minimizing therapeutic intervention or even enabling disease reversal. Protein biomarkers are of particular interest given their central role in biochemical pathways. Hence, capabilities to analyze multiple protein biomarkers in one assay are highly interesting for biomedical research. Areas covered: We here review multiple methods that are suitable for robust, high throughput, standardized, and affordable analysis of protein biomarkers in a multiplex format. We describe innovative developments in immunoassays, the vanguard of methods in clinical laboratories, and mass spectrometry, increasingly implemented for protein biomarker analysis. Moreover, emerging techniques are discussed with potentially improved protein capture, separation, and detection that will further boost multiplex analyses. Expert commentary: The development of clinically applied multiplex protein biomarker assays is essential as multi-protein signatures provide more comprehensive information about biological systems than single biomarkers, leading to improved insights in mechanisms of disease, diagnostics, and the effect of personalized medicine

Pestisit tayinine yönelik biyosensör geliştirilmesi ve karakterizasyonu

Pestisitlerin dünyada yaygınlaşan kullanımları, bu maddelerin çevresel analizlerine gösterilen ilgiyi arttırmaktadır. Geçmişte yaygın olarak kullanılan DDT, Aldrin, Lindan gibi organoklorlu insektisitlerin yerini günümüzde organofosfat pestisitleri almıştır. Bu grup bileşikler, çevresel kalıcılıkları organoklorlu maddelere göre daha az olmasına rağmen, akuatik ekosistemin dengesine yönelik ciddi bir problem yaratacak yüksek akut toksisiteye sahiptirler. Bu özellikten kaynaklanan ve insan sağlığını direk etkileyecek bir diğer önemli sorun ise gıda kontaminasyonudur. Ayrıca, bu maddelerin toksisitesi nedeniyle pestisit üretiminde çalışan işçilerin ve kullanıcıların sağlığının ciddi bir şekilde etkilendiği açıktır. Pestisit analizleri genellikle gaz kromatografisi ve HPLC gibi yöntemler ile gerçekleştirilmektedir. Ancak bu metodlar genellikle bir takım ön işlemleri (deriştirme vb.) gerektirmektedir ve yerinde analizler için kullanımları uygun değildir. Kolin esterazların inhibisyonlarını temel alan biyosensör sistemleri bu amaca yönelik oldukça kullanışlı sistemlerdir. Asetil- yada bütirilkolin klorürün enzimatik hidrolizi sonucu açığa çıkan protonun bir transduser ile tayini kolaylıkla mümkündür ve enzim inhibisyonu sonucunda enzimatik reaksiyon ürünündeki azalma pestisit konsantrasyonuyla orantılı olmaktadır. Bu çalışmada, organofosfat pestisitlerinin potansiyometrik tayinlerine yönelik asetilkolin esteraz(AChE) ve bütirilkolin esteraz(BuChE) enzimlerini temel alan jelatin ve kitosan tabanlı pratik biyosensörlerin hazırlanması hedeflenmiştir. Öncelikle, her iki enzim de sırasıyla jelatin ve kitosan membranlar vasıtasıyla pH elektrotları üzerine immobilize edilerek, jelatin ve kitosan tabanlı AChE ve BuChE enzim elektrotları hazırlanmış ve karakterizasyonları gerçekleştirilmiştir. Biyosensör performansını etkileyen bazı parametreler (pH, sıcaklık, substrat konsantrasyonu, organik çözgenler) araştırılarak, enzim elektrotlarının kararlılığı belirlenmiştir. Bunların yanısıra, pestisit tayinine yönelik olarak kullanılabilirlikleri incelenerek, bu amaca yönelik en uygun sistem tesbit edilmiştir

Preface

WOS: 00024805160000

Towards the electrochemical diagnosis of cancer: nanomaterial-based immunosensors and cytosensors

WOS: 000389708700022In this review, nanomaterial based electrochemical biosensors including electrochemical immunosensors and cytosensors towards cancer detection are covered. Brief definitions of biosensors together with nanomaterials are presented. Electrochemical biosensors for cancer biomarkers and cytosensors are listed. Also, the potential of adaptation of these biosensors to point of care systems is discussed

L’éducation de l’élite féminine dans l’Empire Ottoman au XIXe siècle : Le Pensionnat de filles de Notre-Dame de Sion d’Istanbul (1856)

Le pensionnat de filles de Notre-Dame de Sion d’Istanbul (1856) connut une grande réputation auprès des familles aisées stambouliotes de diverses races et confessions  tournées vers l’Occident et soucieuses de l’éducation tant langagière que culturelle de leurs filles ayant pour vocation d’être de futures épouses et mères. Notre sujet porte sur l’étude de ce prestigieux pensionnat pendant la période de 1856-1912 et sur le rôle et l’importance de l’apprentissage du français des filles au sein d’une société cosmopolite stambouliote.  The girls’ private boarding school of Istanbul Notre Dame de Sion was well-received by the wealthy families of Istanbul who were of different races and religions but turned their faces to the West and were concerned with the education of their daughters, namely the mothers and wives of the future. This study focuses on the 1856-1912 curriculum of this prestigious boarding school as well as the role and importance of learning French in the education of girls in a cosmopolitan Istanbul