03009nas a2200241   4500008004100000245014100041210006900182260000800251300001200259490000800271520213000279100002102409700002302430700002202453700002402475700002802499700002402527700002302551700002402574700002302598700002202621856012402643       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  uhttp://library.ncl.res.in/content/porous-reduced-graphene-oxide-modified-electrodes-analysis-protein-aggregation-part-1