J. Zhang, S. Arbault, N. Sojic, D. Jiang
Annu. Rev. Anal. Chem. 2019. 12.
Electrochemiluminescence (ECL) is a widely used analytical technique with the advantages of high sensitivity and low background signal. The recent and rapid development of electrochemical materials, luminophores, and optical elements significantly increases the ECL signals and, thus, ECL imaging with enhanced spatial and temporal resolutions is realized. Currently, ECL imaging is successfully applied to high-throughput bioanalysis and to visualize the distribution of molecules at single cells. Compared with other optical bioassays, no optical excitation is involved in imaging, so the approach avoids a background signal from illumination and increases the detection sensitivity. This review highlights some of the most exciting developments in this field, including the mechanisms, electrode designs, and the applications of ECL imaging in bioanalysis and at single cells and particles.
B. Gupta, M. C. Afonso, L. Zhang, C. Ayela, P. Garrigue, B. Goudeau, A. Kuhn
ChemPhysChem 7 (2019) 941 (Cover)
Combining the actuation of conducting polymers with additional functionalities is an interesting fundamental scientific challenge and increases their application potential. Here we demonstrate the possibility of direct integration of a miniaturized light emitting diode (LED) in a polypyrrole (PPy) matrix in order to achieve simultaneous wireless actuation and light emission. A light emitting diode is used as a part of an electroactive surface on which electrochemical polymerization allows direct incorporation of the electronic device into the polymer. The resulting free-standing polymer/LED hybrid can be addressed by bipolar electrochemistry to trigger simultaneously oxidation and reduction reactions at its opposite extremities, leading to a controlled deformation and an electron flow through the integrated LED. Such a dual response in the form of actuation and light emission opens up interesting perspectives in the field of microrobotics.
M. Dąbrowski, A. Ziminska, J. Kalecki, M. Cieplak, W. Lisowski, R. Maksym, S. Shao, F. D’Souza, A. Kuhn, P. S. Sharma
ACS Applied Materials and Interfaces 11 (2019) 9265
We present an improved approach for the preparation of highly selective and homogeneous molecular cavities in molecularly imprinted polymers (MIP) via the combination of surface imprinting and semi-covalent imprinting. Towards that, first a colloidal crystal mold was prepared via the Langmuir-Blodgett technique. Then, human chorionic gonadotropin (hCG) template protein was immobilized on the colloidal crystal mold. Later, hCG derivatization with electroactive functional monomers via amide chemistry was performed. In a final step, optimized potentiostatic polymerization of 2,3′-bithiophene enabled depositing an MIP film as macroporous structure. This synergistic strategy resulted in the formation of molecular imprinted cavities exclusively on the internal surface of the macropores, which were accessible after dissolution of silica molds. The recognition of hCG by the macroporous MIP film was transduced with the help of electric transducers, namely extended-gate field-effect transistors (EG-FET) and capacitive impedimetry (CI). These readout strategies offer the ability to create chemosensors for the label-free determination of hCG hormone. Other than the simple confirmation of pregnancy, hCG assay is a common tool for the diagnosis and follow-up of ectopic pregnancy or trophoblast tumors. Concentration measurements with these EG-FET and capacitive impedimetry based devices allowed real-time measurements of hCG in the range of 0.8 to 900 fM and 0.17 to 2.0 fM, respectively in 10 mM carbonate buffer (pH = 10). Moreover, the selectivity of the chemosensors with respect to protein interferences was very high.
I. Malytska, Th. Doneux, M. Bougouma, A. Kuhn, L. Bouffier.
J. Phys. Chem. C, 123, 2019, 5647
Doping of a transition-metal dichalcogenide deposited onto a conducting surface acting as bipolar electrode was recently reported. Here, freestanding macro- and microscale transition-metal dichalcogenide substrates are successfully employed as effective bipolar electrodes without the need of using an additional conducting support. This is first demonstrated by achieving site-selective bipolar electrodeposition of several metals, such as gold, silver, copper, and nickel, on macroscale MoSe2 substrates (typically 1 mm in size). Also, the superior efficiency of MoSe2 compared to that of a carbon substrate toward hydrogen evolution reaction, well-known in conventional electrochemistry, is demonstrated in the bipolar electrochemistry configuration. Such electrocatalytic properties can be advantageously used by combining this reduction with a given oxidation reaction to ease the electro-chemical coupling. Also, as a wireless technique, bipolar electrochemistry enables the simultaneous addressing of large ensembles of bipolar electrodes with a single pair of driving electrodes. Therefore, in a bulk experiment, a suspension composed of thousands of individual MoSe2 microparticles (with a typical size of 20−80 μm) that are addressed simultaneously, is employed to significantly accelerate electrolysis. Amplex Red was selected as an oxidizable organic model dye. Such electrolysis occurs on the timescale of several seconds, which is definitely not achievable by addressing a single macroscale MoSe2 bipolar electrode. This performance is due to the collective behavior of the ensemble of MoSe2 bipolar electrodes because the oxidation process occurs simultaneously at each individual anodic pole.