Single Electrochemical Impacts of Shewanella oneidensis MR-1 Bacteria for Living Cells Adsorption onto a Polarized Ultramicroelectrode Surface

Funding Information: This work is supported by Nantes Université and the Région Pays de la Loire (Rising stars program, e-NANOBIO). The authors acknowledge the France-Portugal PHC PESSOA 2022 program for support, project 47857YM. Funding Information: This work is supported by Nantes Université and the Région Pays de la Loire (Rising stars program, NANOBIO). The authors acknowledge the France‐Portugal PHC PESSOA 2022 program for support, project 47857YM. e‐ Publisher Copyright: © 2022 The Authors. ChemElectroChem published by Wiley-VCH GmbH.Single electrochemical impacts of Shewanella oneidensis MR-1 Gram-negative electroactive bacteria onto ultramicroelectrode surfaces are reported and in-depth analysed. Chronoamperometry measurements recorded onto 10 μm-diameter Pt and 7 μm-diameter carbon fibre disk ultramicroelectrodes in a 20 mM potassium ferrocyanide aqueous solution in the presence of living bacteria show an electrostatic attraction of Shewanella cells onto the ultramicroelectrode surface polarized at +0.8 V vs Ag/AgCl. Single current step events analysis and atomic force microscopy experiments confirm the adsorption of living bacteria following the collision onto the ultramicroelectrode surface. The bacteria washing step before the chronoamperometry measurements leads to lower current step events related to the smaller size of the living cells. The electrostatic attraction of the negatively charged bacteria onto the positively charged ultramicroelectrode surface polarized at the oxidation potential of ferrocyanide is clearly demonstrated.publishersversionpublishe

Organostanniques [alpha]-aminés chiraux (synthèse diastéréosélective, déprotection électrochimique et applications en synthèse asymétrique)

Les organostanniques a-aminés chiraux constituent des précurseurs d anions a-aminés optiquement actifs très utiles en synthèse organique. Dans ce contexte, nous avons développé une nouvelle approche permettant d y accéder diastéréosélectivement. Dans une première partie, la préparation et l ouverture de 2-tributylstannyl-1,3-oxazolidines N-protégées pour donner des a-tributylstannyl amino alcools optiquement actifs ont été décrites. Une étude mécanistique sur la réaction d ouverture a été menée afin de rationaliser les résultats observés, notamment les hautes diastéréosélectivités obtenues dans le cas des oxazolidines N-arènesulfonylées. La désulfonylation des a-tributylstannyl amino alcools N-benzènesulfonylés obtenus a ensuite été étudiée. Après considération du mécanisme mis en jeu, la réduction électrochimique a pu être appliquée avec succès à la déprotection d organostanniques a-aminés N-benzènesulfonylés. La transmétallation des organostanniques a-aminés N-tertiobutoxycarbonylés en organolithiens correspondants a permis l obtention de molécules azotées chirales d intérêt biologique après piégeage par des agents électrophiles. La synthèse stéréocontrôlée de l Alafosfalin ainsi que celle d acides aminés issus de la transmétallation de N-(a-tributylstannylorgano)oxazolidinones ont constitué les deux principales illustrations du potentiel synthétique de ces nouveaux outils.Enantioenriched a-aminoorganostannanes have emerged as useful reagents for organic synthesis. In this context, we have developed a new route to chiral a-aminoorganostannanes. The preparation of N-protected 2-tributylstannyl-1,3-oxazolidines and ring-opening of these heterocycles to afford optically active a-tributylstannyl amino alcohols were first considered. Mechanistic studies on ring-opening reaction were conducted to explain the stereochemical outcomes, particularly the high diastereoselectivities obtained in the case of N-arenesulfonyl oxazolidines. We then embarked upon the desulfonylation of the obtained N-benzenesulfonyl a-tributylstannyl amino alcohols. After a detailed investigation, the electrochemical reduction was applied successfully to the deprotection of N-benzenesulfonyl a-aminoorganostannanes. Transmetalation of N-tertiobutoxycarbonyl a-aminoorganostannanes afforded the corresponding a-aminolithiums reagents whose electrophilic trapping gave chiral nitrogen-containing compounds of biological interest. Thus, the transmetalation reaction was applied to the asymmetric synthesis of an a-amino phosphonic acid : Alafosfalin. Finally, the transcarbamoylation reaction of chiral a-tributylstannyl amino alcohols was explored to afford optically active N-(a-tributylstannylorgano)oxazolidin-2-ones.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Recent advances in single liposome electrochemistry

International audienceSingle liposome electrochemistry is a very sensitive and versatile electroanalytical tool for understanding biological processes and fundamental mechanisms occurring at the lipid membrane / electrode interface. The extension of the electrochemistry of single redox liposome impact for sensing applications represents a great opportunity for detecting various biotargets in a short time of analysis with a high sensitivity. Both the electrochemistry of individual vesicle impact onto a surface of ultramicroelectrode and the detection of the electroactive content encapsulated in a giant unilamellar vesicle are reported in this review and illustrated with recent examples. The limitations, applications, perspectives and challenges of single liposome electrochemistry are briefly discussed based on the last published studies

Preparation of functionalized aryl- and heteroarylpyridazines by nickel-catalyzed electrochemical cross-coupling reactions

0022-3263International audienceA general efficient electrochemical method for the preparation of aryl- and heteroarylpyridazines in a nickel-catalyzed cross-coupling reaction of 3-chloro-6-methoxypyridazine and 3-chloro-6-methylpyridazine with a range of functionalized aryl or heteroaryl halides is reported

Electrochemical Cleavage of Sulfonamides: An Efficient and Tunable Strategy to Prevent β-Fragmentation and Epimerization

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Some mechanistic aspects of a nickel-catalyzed electrochemical cross-coupling between aryl halides and substituted chloropyridazines

The nickel-2,2'-bipyridine catalyzed electrochemical cross-coupling reaction between an aryl halide and a chloropyridazine was investigated by an electrochemical study The electrochemical behavior of the divalent nickel complex is affected by the presence of pyridazine rings which act as co-ligands of nickel Cyclic voltammetry indicates that the cross-coupling reaction involves first a rapid oxidative addition of the chloropyridazine on the electrogenerated zerovalent nickel complex. The coupling product is then obtained by reaction with the aryl halide. (C) 2010 Elsevier Ltd. All rights reserved

Electrochemically promoted tyrosine-click-chemistry for protein labeling

International audienceThe development of new bio-orthogonal ligation methods for the conjugation of native proteins is of particular importance in the field of chemical biology and biotherapies. In this work, we developed a traceless electrochemical method for protein bioconjugation. The electrochemically promoted tyrosine-click (e-Y-CLICK) allowed the chemoselective Y-modification of peptides and proteins with labeled urazoles. A low potential is applied in an electrochemical cell to activate urazole anchors in situ and on demand, without affecting the electroactive amino acids from the protein. The versatility of the electrosynthetic approach was shown on biologically relevant peptides and proteins such as oxytocin, angiotensin 2, serum bovine albumin, and epratuzumab. The fully conserved enzymatic activity of a glucose oxidase observed after e-Y-CLICK further highlights the softness of the method. The e-Y-CLICK protocols were successfully performed in pure aqueous buffers, without the need for co-solvents, scavenger or oxidizing chemicals, and should therefore significantly broaden the scope of bioconjugation

Pd-Catalyzed Chemoselective Cross-Coupling Reaction of Triaryl- or Triheteroarylbismuth Compounds with 3,6-Dihalopyridazines

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An Electrochemical Nickel-Catalyzed Arylation of 3-Amino-6-Chloropyridazines

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Electrochemical Cleavage of Sulfonamides: An Efficient and Tunable Strategy to Prevent β-Fragmentation and Epimerization

The electrochemical reduction of sensitive sulfonamides is described. The addition of a benzoyl group on the nitrogen atom facilitates the reductive cleavage of sulfonamides preventing β-fragmentation and epimerization. This strategy was successfully applied to the cyclopropylamine and to α-amino stannanes