02222nas a2200277   4500008004100000022001400041245009600055210006900151260000800220300001400228490000600242520131000248653002601558653001701584653001201601653001701613653003401630100002201664700002301686700002101709700002401730700002401754700002301778700002201801856012101823       2016                        eng d  a2379-369400aReduced graphene oxide modified electrodes for sensitive sensing of gliadin in food samples0 aReduced graphene oxide modified electrodes for sensitive sensing  cDEC  a1462-14700 v13 a<p>Incidences of food allergies are on the rise, which can greatly affect the well-being of children as well as adults. Intolerance to gluten, a protein composite of gliadin and glutenin, present in wheat, barley, and rye and several cereals, can be the causative agent of celiac disease (CD) and other allergic reactions. A gluten-free diet has become essential for people affected by CD, and consequently, the amount of gluten in food products needs to be strictly controlled. In this paper, we report an electrochemical label-free immunosensor for ultrasensitive and specific detection of gliadin. The sensor takes advantage of the specific properties of porous reduced graphene oxide (prGO) covalently functionalized with anti-gliadin antibodies using 1-pyrenecarboxylic acid as linker molecule. Using differential pulse voltammetry (DPV) and [Fe(CN)6](3-/4-) as a redox probe, a decrease of current is linked to the presence of gliadin. The sensor achieved a detection limit of 1.2 ng mL(-1) over a 1.2-34 ng mL(-1) linear range with high selectivity. The advantages offered by this sensor are the possibility to regenerate the surface of the immunosensor, its rapid and ease of production, as well as applicability for the screening of gliadin concentrations in real food samples, as shown here.</p>10aanti-gliadin antibody10afood samples10agliadin10aImmunosensor10aPorous reduced graphene oxide1 aChekin, Fereshteh1 aSingh, Santosh, K.1 aVasilescu, Alina1 aDhavale, Vishal, M.1 aKurungot, Sreekumar1 aBoukherroub, Rabah1 aSzunerits, Sabine  uhttps://library.ncl.res.in/content/reduced-graphene-oxide-modified-electrodes-sensitive-sensing-gliadin-food-samples03010nas a2200241   4500008004100000245014100041210006900182260000800251300001200259490000800271520213000279100002102409700002302430700002202453700002402475700002802499700002402527700002302551700002402574700002302598700002202621856012502643       2017                        eng d00a Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. part 1: lysozyme aggregation at pH 2 and 7.40 aPorous reduced graphene oxide modified electrodes for the analys  cNOV  a375-3830 v2543 aProtein instability due to misfolding and aggregation is of big concern for protein based therapeutics because it impacts the bioavailability and immunogenicity of such drugs. The development of simple and cost-effective methods for the analysis of pharmaceutical formulations, indicating the presence or absence of protein aggregates, is consequently of high importance. This work proposes a novel electrochemical interface based on porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) allowing for the early and sensitive identification of protein aggregation by following the change in the oxidative current of the proteins. The novelty of this work lies in the exploration of the ability of GC/prGO interfaces to capture different aggregation behaviors. Lysozyme is used as a model to follow by electrochemistry its aggregation at two pH values, pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Comparing the oxidation peak of lysozyme by differential pulse voltammetry (DPV) for different electrode architectures allowed validating the higher sensitivity of the GC/prGO interface versus bare glassy electrodes or electrodes coated with non-porous reduced graphene oxide. Parallel experiments were performed by fluorescence with thioflavin T, size exclusion chromatography and Atomic Force Microscopy (AFM) imaging. These tests further highlighted the usefulness of GC/prGO electrode to visualize in a fast and reliable manner the changes in the protein structure and the differences between the processes occurring at pH 2 and pH 7.4. In particular, the ability to emphasize changes related to the first steps in aggregation that could be indicative of the aggregation course, recommend the GC/prGO electrode in combination with DPV as a new analytical tool for aggregation studies of biopharmaceuticals. Part 2 of this work will demonstrate later the utility of this approach for the analysis of a fast acting injectable human insulin formulation, Humulin R, used for diabetes treatment as well as for calcitonin. (C) 2017 Elsevier Ltd. All rights reserved.1 aVasilescu, Alina1 aBoulahneche, Samia1 aChekin, Fereshteh1 aGaspar, Szilveszter1 aMedjram, Mohamed, Salah1 aDiagne, Abdou, Aziz1 aSingh, Santosh, K.1 aKurungot, Sreekumar1 aBoukherroub, Rabah1 aSzunerits, Sabine  uhttps://library.ncl.res.in/content/porous-reduced-graphene-oxide-modified-electrodes-analysis-protein-aggregation-part-102837nas a2200337   4500008004100000022001400041245018300055210006900238260000900307300001200316490000800328520165900336653001501995653002602010653002102036653003402057653002402091100002102115700001202136700002302148700002202171700001802193700002802211700002402239700002302263700002402286700001902310700002302329700002202352856012502374       2018                        eng d  a0013-468600aPorous reduced graphene oxide modified electrodes for the analysis of protein aggregation. Part 2: Application to the analysis of calcitonin containing pharmaceutical formulation0 aPorous reduced graphene oxide modified electrodes for the analys  cMAR   a364-3720 v2663 a<p>In part 1 (A. Vasilescu et al., Porous reduced graphene oxide modified electrodes for the analysis of protein aggregation. Part 1: Lysozyme aggregation at pH 2 and 7.4 Electrochem. Acta, 254 (2017) 375 -383) we proposed porous reduced graphene oxide coated glassy carbon electrode (GC/prGO) in combination with differential pulse voltammetry as a new analytical tool for aggregation studies of proteins. Lysozyme was used as a model to follow its aggregation by electrochemical means at pH 2 and pH 7.4, leading to the formation of amyloid and amorphous aggregates, respectively. Part 2 of this work widens the scope of this approach by investigating a biopharmaceutical product, as the aggregation of peptide based drugs affects their therapeutic activity and can induce allergic reactions in patients. The salmon polypeptide calcitonin (sCT) was chosen as an example of a bioactive peptide with limited pharmaceutical potential due to a tendency to form cytotoxic aggregates and amyloid fibrils. For practical applications, screen printed electrodes (SPE) and flexible electrodes (FE) modified with polydiallyldimethylammonium (PDDA) and prGO by using the layer-by-layer deposition technique have been developed for the detection of sCT. The results indicate that these electrodes can differentiate between formation of amyloid aggregates of calcitonin (2 mg mL(-1)) in citrate buffer to no aggregation in acetate buffer. It was further demonstrated that these electrodes are able to analyze a pharmaceutical drug product of low potency, Miacalcic (8.3 mu g mL(-1)), where no aggregation was observed. (C) 2018 Elsevier Ltd. All rights reserved.</p>10aCalcitonin10aDisposable electrodes10aElectrochemistry10aPorous reduced graphene oxide10aProtein aggregation1 aVasilescu, Alina1 aYe, Ran1 aBoulahneche, Samia1 aLamraoui, Sabrina1 aJijie, Roxana1 aMedjram, Mohamed, Salah1 aGaspar, Szilveszter1 aSingh, Santosh, K.1 aKurungot, Sreekumar1 aMelinte, Sorin1 aBoukherroub, Rabah1 aSzunerits, Sabine  uhttps://library.ncl.res.in/content/porous-reduced-graphene-oxide-modified-electrodes-analysis-protein-aggregation-part-201983nas a2200229   4500008004100000245014000041210006900181260000800250300001200258490000800270520115600278100002201434700002101456700001801477700002301495700002401518700002001542700002001562700002301582700002201605856012601627       2018                        eng d00aSensitive electrochemical detection of cardiac troponin I in serum and saliva by nitrogen-doped porous reduced graphene oxide electrode0 aSensitive electrochemical detection of cardiac troponin I in ser  cJUN  a180-1870 v2623 aCardiovascular diseases pose one of the highest mortality risks among all diseases in developed countries, steadily increasing the burden on the health systems. Early diagnosis of cardiovascular diseases has consequently become highly important to decrease mortality and to use more adapted therapeutic decisions. We demonstrate here the utility of nitrogen-doped reduced graphene oxide (N-prGO) for detecting and quantifying of cardiac troponin I (cTnI), a key human cardiac protein biomarker, under physiologically relevant conditions. Non-covalent modification of N-prGO by 1-pyrenecarboxylic acid (py-COOH) and poly(ethylene glycol) modified pyrene (py-PEG) ligands allowed the covalent integration of Tro4 aptamer, known for its high selectivity towards cTnI. Using differential pulse voltammetry (DPV), a label-free electrochemical sensor for cTnI for concentrations down to 1 pgmL(-1) in human serum could be obtained. This sensitive detection arises from the integration of a porous nanomaterial with excellent electrochemical properties being easily amendable to site-specific surface modification. (C) 2018 Elsevier B.V. All rights reserved.1 aChekin, Fereshteh1 aVasilescu, Alina1 aJijie, Roxana1 aSingh, Santosh, K.1 aKurungot, Sreekumar1 aIancu, Madalina1 aBadea, Gabriela1 aBoukherroub, Rabah1 aSzunerits, Sabine  uhttps://library.ncl.res.in/content/sensitive-electrochemical-detection-cardiac-troponin-i-serum-and-saliva-nitrogen-doped