Supplementary data for the article: Habtamu, H. B.; Sentic, M.; Silvestrini, M.; De Leo, L.; Not, T.; Arbault, S.; Manojlovic, D.; Sojic, N.; Ugo, P. A Sensitive Electrochemiluminescence Immunosensor for Celiac Disease Diagnosis Based on Nanoelectrode Ensembles. Analytical Chemistry 2015, 87 (24), 12080–12087. https://doi.org/10.1021/acs.analchem.5b02801

Supporting information for: [https://doi.org/10.1021/acs.analchem.5b02801]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2014

3D electrogenerated chemiluminescence: from surface-confined reactions to bulk emission

Among luminescence techniques, electrogenerated chemiluminescence (ECL) provides a unique level of manipulation of the luminescent process by controlling the electrochemical trigger. Despite its attractiveness, ECL is by essence a 2D process where light emission is strictly confined to the electrode surface. To overcome this intrinsic limitation, we added a new spatial dimension to the ECL process by generating 3D ECL at the level of millions of micro-emitters dispersed in solution. Each single object is addressed remotely by bipolar electrochemistry and they generate collectively the luminescence in the bulk. Therefore, the entire volume of the solution produces light. To illustrate the generality of this concept, we extended it to a suspension of multi-walled carbon nanotubes where each one acts as an individual ECL nano-emitter. This approach enables a change of paradigm by switching from a surface-limited process to 3D electrogenerated light emission

Supplementary data for the article: Habtamu, H. B.; Sentic, M.; Silvestrini, M.; De Leo, L.; Not, T.; Arbault, S.; Manojlovic, D.; Sojic, N.; Ugo, P. A Sensitive Electrochemiluminescence Immunosensor for Celiac Disease Diagnosis Based on Nanoelectrode Ensembles. Analytical Chemistry 2015, 87 (24), 12080–12087. https://doi.org/10.1021/acs.analchem.5b02801

Supporting information for: [https://doi.org/10.1021/acs.analchem.5b02801]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2014

In situ electrochemical monitoring of reactive oxygen and nitrogen species released by single MG63 osteosarcoma cell submitted to a mechanical stress

The oxidative stress responses of single MG63 osteosarcoma cells submitted to a brief mechanical stress have been investigated by amperometry at platinized carbon fiber electrodes for monitoring and characterizing the nature and the amounts of the various reactive oxygen (ROS) and reactive nitrogen species (RNS) released. It was thus shown that, on average, a single MG63 cell released prominent amounts of reactive nitrogen species (17 fmol NO center dot, 6 fmol ONOO-, and 5 fmol NO2-) together with a comparatively small quantity of H2O2 (2 fmol). These species resulted from the primary production of 13 fmol for O-2(center dot-) and 28 fmol for NO center dot per single cell as reconstructed from the stoichiometries of the ROS and RNS releases. The high NO center dot/H2O2 and NO center dot/O-2(center dot-) ratios thus found are perfectly consistent with previous claims that the malignant bone formation ability of the osteosarcoma cells is related to a specific high production of NO center dot associated to a small one of O-2(center dot-)CNRS ; ENS ; UPMC [UMR 8640]; ANR [ANR-06-BLAN-029]; European Community [CP-FP214566-2]; NSFC [20620130427, 20773100]; MOST [2007DFC40440]; 973-Program [2007CB935603]; French Ministry of Research (MESR

Electroactivity of superoxide anion in aqueous phosphate buffers analyzed with platinized microelectrodes

The reactivity of platinized ultramicroelectrodes (Pt-black UMEs) towards superoxide anion O2.−, an unstable Reactive Oxygen Species (ROS), and its relatives, H2O2 and O2, was studied. Voltammetric studies in PBS demonstrate that Pt-black UMEs provide: i) a well-resolved reversible redox signature for O2.− detected in both alkaline and physiological buffers (pH 12 and 7.4); ii) irreversible oxidation and reduction waves for H2O2 at pH 7.4. The oxygen reduction reaction (ORR) at Pt-black surfaces solely yields H2O2 (2 electrons/2 H+) at physiological pH. Consequently, Pt-black UMEs allow to sense different ROS including superoxide anion for future biomedical or physico-chemical investigations

Reactive oxygen species generated by cold atmospheric plasmas in aqueous solution : successful electrochemical monitoring in situ under a high voltage system

International audienceMany investigations are dedicated to the detection and quantification of reactive oxygen and nitrogen species (RONS), particularly when generated in liquids exposed to cold atmospheric plasmas (CAPs). CAPs are partially ionized gases that can be obtained by applying a high electric field to a gas. A challenge is to get better insights on the plasma–liquid interactions in order to understand the induced effects on different targets (liquid, cells, tissues, etc.). As RONS are biochemically reactive, the difficulty lies in finding efficient methods to get both dynamic and quantitative data. Herein, we developed an innovative setup aimed at performing an in situ electrochemical monitoring of redox species generated by CAPs in a physiological buffer (PBS, pH 7.4). The challenge was to apply millivolt-potential variations and measure nanoampere Faradaic currents in the presence of ionization waves generated by micropulsed electric fields of some 10 kV·cm–1 amplitude and ampere-transient currents. This was fulfilled by using dedicated working ultramicroelectrodes (Pt-black UMEs) and protecting them, as well as the reference and counter electrodes, within insulated-earthed containers. In this condition, we succeeded in performing both cyclic voltammetry and chronoamperometry in situ, with a resolution equivalent to working in a static solution (subnanoampere currents). Thus, we monitored the accumulation over time of species (H2O2, NO2–) generated by CAPs in PBS and observed the mean dynamic of RONS chemistry during and after plasma exposition, particularly through the detection of a short-living species

Mapping electrogenerated chemiluminescence reactivity in space: mechanistic insight into model systems used in immunoassays

The remarkable characteristics of electrogenerated chemiluminescence (ECL) as a readout method are successfully exploited in numerous microbead-based immunoassays. However there is still a lack of understanding of the extremely high sensitivity of such ECL bioassays. Here the mechanisms of the reaction of the Ru(bpy)(3)(2+) luminophore with two efficient co-reactants (TPrA or DBAE) were investigated by mapping the ECL reactivity at the level of single Ru(bpy)(3)(2+)-functionalized beads. Micrometric non-conductive beads were decorated with the ruthenium label via a sandwich immunoassay or via a peptide bond. Mapping the ECL reactivity on one bead demonstrates the generation of the excited state at a micrometric distance from the electrode by reaction of surface-confined Ru(bpy)(3)(2+) with diffusing TPrA radicals. The signature of the TPAc center dot+ lifetime is obtained from the ECL profile. Unlike the reaction with Ru(bpy)(3)(2+) in solution, DBAE generates very low ECL intensity in the bead-based format suggesting more unstable radical intermediates. The 3D imaging approach provides insights into the ECL mechanistic route operating in bioassays and on the optical effects that focus the ECL emission

Effect of charge on the stabilization of water-in-water emulsions by thermosensitive bis-hydrophilic microgels

Hypothesis Molecular surfactants are not able to stabilize water-in-water (W/W) emulsions, unlike nano or micro-particles, which can achieve this in some cases. However, the effect of electrostatic interactions between particles on the emulsion stability has rarely been investigated. We hypothesize that introducing charges modifies the stabilization capacity of particles and renders it both pH-and ionic strength-dependent. Experiments Charge was introduced into bis-hydrophilic and thermoresponsive dextran/polyNisopropylacrylamide microgels by replacing a small fraction of polyN-isopropylacrylamide with acrylic acid groups. The size of the microgels was obtained by dynamic light scattering. The stability and microstructure of dextran/poly(ethyleneoxide)-based W/W emulsions, wasRéactions enzymatiques oscillantes dans des gouttes aqueuses métastable