Haidong Li, Silvia Voci, Antoine Wallabregue, Catherine Adam, Geraldine M. Labrador, Romain Duwald, Irene HernÃ¡ndez Delgado, Simon Pascal, Johann Bosson, JÃ©rÃ´me Lacour, Laurent Bouffier, Neso Sojic
The electrochemistry and annihilation electrochemiluminescence (ECL) of a series of chiral cationic helicene luminophores containing various substituents were investigated in acetonitrile as solvent. The electrochemical characterization evidenced a systematic reversible reduction of the cation whereas the oxidation could be reversible or not depending on the nature of the core heteroatoms within the structure as well as the functional group appendages. One of the key-parameters governing the ECL intensity is indeed the formal redox potentials for the electrogeneration of the neutral radical and dication radical species which will undergo the annihilation reaction. On that basis, a thermodynamic wall of efficiency was proposed in the case of ECL annihilation pathway to predict the formation efficiency of the emitting excited state and eventually light emission strength. This very simple wall is constructed by plotting the difference of formal potentials in function of the fluorescence wavelength delimiting thus two domains where ECL is thermodynamically possible or unfavorable.
The great success of electrogenerated chemiluminescence (ECL) in analytical chemistry can be measured by the widespread use of the technology in different fields, ranging from basic research to commercial clinical and biological applications. Indeed, this remarkable readout method offers intrinsic advantages by comparison to other transduction methods: high sensitivity, extremely wide dynamic range and insensitivity to matrix effects. In addition, its versatility allows exploiting various types of biomolecular interactions and therefore to detect specifically targeted analytes of biological interest such as proteins, nucleic acids and enzymatic substrates. Numerous assay formats, biosensors or analytical strategies with new ECL labels or with label-free approaches have been proposed by using nanostructured materials: carbon nanotubes, metal or doped nanoparticles, graphene, carbon dots, quantum dots or ultrathin films. The development of analytical ECL has also been fueled by discovering novel luminophores and efficient coreactants and also by deciphering the complexity of the ECL mechanisms at the minute scale. The combination of ECL with microfluidics, paper-based materials, bipolar electrochemistry, and portable miniaturized devices has led to various intriguing and promising analytical applications.
D. Jain, A. Karajic, M. Murawska, B. Goudeau, S. Bichon, S. Gounel, N. Mano, A. Kuhn, P. Barthélémy
Controlling the interface between biological tissues and electrodes remains an important challenge for the development of implantable devices in terms of electroactivity, biocompatibility, and long-term stability. To engineer such a biocompatible interface a low molecular weight gel (LMWG) based on a glycosylated nucleoside fluorocarbon amphiphile (GNF) was employed for the first time to wrap gold electrodes via a noncovalent anchoring strategy, that is, self-assembly of GNF at the electrode surface. Scanning electron microscopy (SEM) studies indicate that the gold surface is coated with the GNF hydrogels. Electrochemical measurements using cyclic voltammetry (CV) clearly show that the electrode properties are not affected by the presence of the hydrogel. This coating layer of 1 to 2 Î¼m does not significantly slow down the mass transport through the hydrogel. Voltammetry experiments with gel coated macroporous enzyme electrodes reveal that during continuous use their current is improved by 100% compared to the noncoated electrode. This demonstrates that the supramolecular hydrogel dramatically increases the stability of the bioelectrochemical interface. Therefore, such hybrid electrodes are promising candidates that will both offer the biocompatibility and stability needed for the development of more efficient biosensors and biofuel cells.
L. Bouffier, D. Zigah, N. Sojic, A. Kuhn
The concept of bipolar electrochemistry has been known for several decades. However with the advent of micro- and nanotechnology there is considerable renewed interest in this approach as it has become apparent that there are extremely attractive features of bipolar electrochemistry for completely new applications in areas ranging from analytical chemistry to materials science. In this extended book chapter we present the most recent advances in this exciting field of research.
A. Karajic, S. Reculusa, S. Ravaine, N. Mano, A. Kuhn
To design original electrochemical devices, self-assembly and growth processes can be coupled to create a wide range of sophisticated architectures with interesting functionalities. In this work, we present a convergent strategy for the fabrication of a miniaturized, macroporous, and coaxial two-electrode electrochemical cell with tunable porosity, thickness, and distance between individually addressable macroporous electrodes. The assembly presents a platform that could be used for the fabrication of high-performance electrochemical devices such as miniaturized (bio)fuel cells, sensors, and batteries.
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