Herein is reported a surface-confined microscopy based on electrochemiluminescence (ECL) that allows to image the plasma membrane of single cells at the interface with an electrode. By analyzing photoluminescence (PL), ECL and AFM images of mammalian CHO cells, we demonstrate that, in contrast to the wide-field fluorescence, ECL emission is confined to the immediate vicinity of the electrode surface and only the basal membrane of the cell becomes luminescent. The resulting ECL microscopy reveals details that are not resolved by classic fluorescence microscopy, without any light irradiation and specific setup. The thickness of the ECL-emitting regions is ∼500 nm due to the unique ECL mechanism that involves short-lifetime electrogenerated radicals. In addition, the reported ECL microscopy is a dynamic technique that reflects the transport properties through the cell membranes and not only the specific labeling of the membranes. Finally, disposable transparent carbon nanotube (CNT)-based electrodes inkjet-printed on classic microscope glass coverslips were used to image cells in both reflection and transmission configurations. Therefore, our approach opens new avenues for ECL as a surface-confined microscopy to develop single cell assays and to image the dynamics of biological entities in cells or in membranes.
Hanan Al-Kutubi, Silvia Voci, Liza Rassaei, Neso Sojic, Klaus Mathwig
Microfabricated nanofluidic electrochemical devices offer a highly controlled nanochannel geometry; they confine the volume of chemical reactions to the nanoscale and enable greatly amplified electrochemical detection. Here, the generation of stable light emission by electrochemiluminescence (ECL) in transparent nanofluidic devices is demonstrated for the first time by exploiting nanogap amplification. Through continuous oxidation and reduction of [Ru(bpy)3]2+ luminophores at electrodes positioned at opposite walls of a 100-nm nanochannel, we compare classic redox cycling and ECL annihilation. Enhanced ECL light emission of attomole luminophore quantities is evidenced under ambient conditions due to the spatial confinement in a 10-femtoliter volume, resulting in a short diffusion timescale and highly efficient ECL reaction pathways at the nanoscale.
H. Labie, A. Perro, V. Lapeyre, B. Goudeau, B. Catargi, R. Auzély, V. Ravaine
A simple route to deliver on demand hydrosoluble molecules such as peptides, packaged in biocompatible and biodegradable microgels, is presented. Hyaluronic acid hydrogel particles with a controlledstructure are prepared using a microfluidic approach. Their porosity and their rigidity can be tuned bychanging the crosslinking density. These negatively-charged polyelectrolytes interact strongly withpositively-charged linear peptides such as poly-L-lysine (PLL). Their interactions induce microgel deswellingand inhibit microgel enzymatic degradability by hyaluronidase. While small PLL penetrate the wholevolume of the microgel, PLL larger than the mesh size of the network remain confined at its periphery.They make a complexed layer with reduced pore size, which insulates the microgel inner core fromthe outer medium. Consequently, enzymatic degradation of the matrix is fully inhibited and nonaffinityhydrophilic species can be trapped in the core. Indeed, negatively-charged or small neutral peptides,without interactions with the network, usually diffuse freely across the network. By simple additionof large PLL, they are packaged in the core and can be released on demand, upon introduction ofan enzyme that degrades selectively the capping agent. Single polyelectrolyte layer appears as a simplegeneric method to coat hydrogel-based materials of various scales for encapsulation and controlled delivery ofhydrosoluble molecules.
Les mesures sélectives et sensibles dans des échantillons complexes tels que l’urine ou le sang sont devenues des outils indispensables dans le domaine du diagnostic. Le développement de nouvelles méthodes d’analyse, plus sensibles, dynamiques, à haut débit représente un défi d’une grande importance sociétale. L’électrochimiluminescence (ECL) constitue une méthode largement commercialisée pour l’immunodosage. Cet article présente des travaux qui portent, d’une part sur la compréhension fine des mécanismes de l’ECL mis en jeu et, d’autre part, sur le développement de l’ECL pour la bioanalyse, avec un accent particulier sur le couplage entre l’électrochimie bipolaire et l’ECL.
E.Krisch, B. Gyarmati, D. Barczikai, V. Lapeyre, B.A. Szilágyi, V. Ravaine, A. Szilágyi
Redox and pH responsive hydrogels were synthesized, which can serve as matrices for smart drug deliveryRedox and pH responsive hydrogels were synthesized, which can serve as matrices for smart drug deliverysystems exploiting the redox and pH gradients in the human body. Water soluble thiolated poly(aspartic acid), abiocompatible synthetic polymer, enables us to cross-link in water with a non-cleavable cross-linker, poly(ethylene glycol) diglycidyl ether. The permanent cross-linker establishes stable polymer hydrogels regardless ofthe redox environment, thus the gels swell but do not dissolve upon redox stimuli. The reversible response uponredox stimulus was induced by thiol-disulphide transformation inside the hydrogel. The degree of swelling andthe stiffness of the macroscopic hydrogels were controlled by their chemical composition including thiol contentand cross-linking ratio as well as the redox state of the hydrogels. The degree of swelling of the hydrogels showedstrong pH dependence due to the polyelectrolyte nature of the polymer network. Release of a macromolecularmodel drug was considerably faster in reducing than in oxidising environment, which indicates the potential useof the synthesized hydrogels as redox responsive drug delivery systems. Nanogels were prepared in water-in-oilemulsion and displayed redox-responsive properties. The hydrodynamic diameter of the nanogels strongly increasedupon the cleavage of the disulphide linkages in reducing solution without the disruption of the gels.
Wednesday, 14 November 2018
S. Voci, B. Goudeau, G. Valenti, A. Lesch, M. Jović, S. Rapino, F. Paolucci, S. Arbault, N. Sojic J. Am. Chem. Soc., 140, 2018, 14753-14760 Herein is reported a surface-confined microscopy based on electrochemiluminescence (ECL) that allows to... Read More...
Wednesday, 14 November 2018
Hanan Al-Kutubi, Silvia Voci, Liza Rassaei, Neso Sojic, Klaus Mathwig Chem .Sci., 9, 2018, (2018 Chemical Science HOT Article Collection) Microfabricated nanofluidic electrochemical devices offer a highly controlled nanochannel geometry; they... Read More...
Wednesday, 14 November 2018
L. Bouffier, S. Arbault, A. Kuhn, N. Sojic Techniques de l’Ingénieur. 2018. P156 Les mesures sélectives et sensibles dans des échantillons complexes tels que l’urine ou le sang sont devenues des outils indispensables dans le domaine du... Read More...