No abstract

Classical electrochemical characterization tools cannot avoid averaging between the active reaction sites and their support, thus obscuring their intrinsic roles. Single-molecule electrochemical techniques are thus in high demand. Here, we demonstrate superresolution imaging of Ru(bpy) 3 2 + based reactions on Au plates using single-molecule electrochemiluminescence microscopy. By converting electrochemical signals into optical signals, we manage to achieve the ultimate sensitivity of single-entity chemistry, that is directly resolving the single photons from individual electrochemical reactions. High spatial resolution, up to 37 nm, further enables mapping Au chemical activity and the reaction kinetics. The spatiotemporally resolved dynamic structure-activity relationship on Au plates shows that the restructuring of catalysts plays an important role in determining the reactivity. Our approach may lead to gaining new insights towards evaluating and designing electrocatalytic systems.

A single-molecule electrochemiluminescence bioassay is developed here which allows imaging and direct quantification of single biomolecules. Imaging single biomolecules is realized by localizing the electrochemiluminescence events of the labeled molecules. Such an imaging system allows mapping the spatial distribution of biomolecules with electrochemiluminescence and contains quantitative single-molecule insights. We further quantify biomolecules by spatiotemporally merging the repeated reactions at one molecule site and then counting the clustered molecules. The proposed single-molecule electrochemiluminescence bioassay is used to detect carcinoembryonic antigen, showing a limit of detection of 67 attomole concentration which is 10 000 times better than conventional electrochemiluminescence bioassays. This spatial resolution and sensitivity enable single-molecule electrochemiluminescence bioassay a new toolbox for both specific bioimaging and ultrasensitive quantitative analysis.

Rapid and accurate identification of pathogens is crucial for public healthcare and patient treatment. However, the commonly used analytic tools such as molecular diagnostics and mass spectrometry are either expensive or have long turnaround times for sample purification and amplification. Here, we introduce electrochemiluminescence (ECL) microscopy with a high spatiotemporal resolution and a unique chemical contrast to image and identify single bacteria. Direct bacterial counting and classification with an accuracy of up to 90.5% is demonstrated. We further report a novel tunable ECL imaging mode which can switch from the negative contrast ECL imaging without labeling to positive contrast ECL imaging with adsorption of tris(2,2′-bipyridyl) ruthenium(II) for bacterial imaging. With this contrast tuning effect, single-molecule ECL microscopy is employed for imaging the microscopic structures of single bacteria. This work shows that ECL microscopy can offer a powerful quantitative imaging methodology with chemical information for bacterial characterization.

Classical electrochemical characterization tools cannot avoid averaging between the active reaction sites and their support, thus obscuring their intrinsic roles. Single-molecule electrochemical techniques are thus in high demand. Here, we demonstrate superresolution imaging of Ru(bpy) 3 2 + based reactions on Au plates using single-molecule electrochemiluminescence microscopy. By converting electrochemical signals into optical signals, we manage to achieve the ultimate sensitivity of single-entity chemistry, that is directly resolving the single photons from individual electrochemical reactions. High spatial resolution, up to 37 nm, further enables mapping Au chemical activity and the reaction kinetics. The spatiotemporally resolved dynamic structure-activity relationship on Au plates shows that the restructuring of catalysts plays an important role in determining the reactivity. Our approach may lead to gaining new insights towards evaluating and designing electrocatalytic systems.