Wireless Synthesis and Activation of Electrochemiluminescent Thermoresponsive Janus Objects Using Bipolar Electrochemistry

In this work, bipolar electrochemistry (BPE) is used as a dual wireless tool to generate and to activate a thermoresponsive electrochemiluminescent (ECL) Janus object. For the first time, BPE allows regioselective growth of a poly­(<i>N</i>-isopropylacrylamide) (pNIPAM) hydrogel film on one side of a carbon fiber. It is achieved thanks to the local reduction of persulfate ions, which initiate radical polymerization of NIPAM. By controlling the electric field and the time of the bipolar electrochemical reactions, we are able to control the length and the thickness of the deposit. The resulting pNIPAM film is found to be swollen in water at room temperature and collapsed when heated above 32 °C. We further incorporated a covalently attached ruthenium complex luminophore, Ru­(bpy)₃²⁺, in the hydrogel film. In the second time, BPE is used to activate remotely the electrogenerated chemiluminescence (ECL) of the Ru­(bpy)₃²⁺ moieties in the film. We take advantage of the film responsiveness to amplify the ECL signal. Upon collapse of the film, the ECL signal, which is sensitive to the distance between adjacent Ru­(bpy)₃²⁺ centers, is strongly amplified. It is therefore shown that BPE is a versatile tool to generate highly sophisticated materials based on responsive polymers, which could lead to sensitive sensors

Single Cell Electrochemiluminescence Imaging: From the Proof-of-Concept to Disposable Device-Based Analysis

We report here the development of coreactant-based electrogenerated chemiluminescence (ECL) as a surface-confined microscopy to image single cells and their membrane proteins. Labeling the entire cell membrane allows one to demonstrate that, by contrast with fluorescence, ECL emission is only detected from fluorophores located in the immediate vicinity of the electrode surface (i.e., 1–2 μm). Then, to present the potential diagnostic applications of our approach, we selected carbon nanotubes (CNT)-based inkjet-printed disposable electrodes for the direct ECL imaging of a labeled plasma receptor overexpressed on tumor cells. The ECL fluorophore was linked to an antibody and enabled to localize the ECL generation on the cancer cell membrane in close proximity to the electrode surface. Such a result is intrinsically associated with the unique ECL mechanism and is rationalized by considering the limited lifetimes of the electrogenerated coreactant radicals. The electrochemical stimulus used for luminescence generation does not suffer from background signals, such as the typical autofluorescence of biological samples. The presented surface-confined ECL microscopy should find promising applications in ultrasensitive single cell imaging assays