02219nas a2200241   4500008004100000245011100041210006900152260000800221300001400229490000600243520137800249100002301627700001801650700002201668700002201690700002301712700002101735700002801756700002401784700002301808700002201831856012401853       2017                        eng d00aOn demand electrochemical release of drugs from porous reduced graphene oxide modified flexible electrodes0 ademand electrochemical release of drugs from porous reduced grap  cAUG  a6557-65650 v53 aDespite the advantages of an electrochemical control for drug release, only a handful of electrochemical-based release systems have been developed so far. We report herein on the development of an electrochemically activatable platform for on-demand delivery of drugs. It is based on flexible gold thin film electrodes coated with porous reduced graphene oxide (prGO) nanosheets onto which the drug of interest has been integrated beforehand. Two different drugs are investigated here: ondansetron hydrochloride (ODS), a selective 5-HT3 receptor antagonist used for preventing nausea and vomiting caused by chemotherapy and radiotherapy, and ampicillin (AMP), an antibiotic to prevent and treat a number of bacterial infections such as respiratory tract infections, urinary tract infections, and meningitis. In the case of ODS, application of a negative potential bias of -0.8 V results in a sustained slow ODS release with an ODS flux of 47 mu g cm(-2) h(-1). In the case of AMP, we show that polyethyleneimine modified prGO (prGO/PEI) is an extremely efficient matrix. Upon the application of +0.8 V, 24% of AMP could be released from the electrical interface in a time span of 2 h. The released AMP kept its antibacterial activity as demonstrated by antimicrobial tests. These examples illustrate the major benefits of the developed approach for biomedical applications.1 aBoulahneche, Samia1 aJijie, Roxana1 aBarras, Alexandre1 aChekin, Fereshteh1 aSingh, Santosh, K.1 aBouckaert, Julie1 aMedjram, Mohamed, Salah1 aKurungot, Sreekumar1 aBoukherroub, Rabah1 aSzunerits, Sabine  uhttps://library.ncl.res.in/content/demand-electrochemical-release-drugs-porous-reduced-graphene-oxide-modified-flexible03010nas 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-2