Editorial – Single Entities

The pioneering developments of condensed-phase single-molecule fluorescence and scanning tunneling microscopy in the 1980s have led to a broad appreciation of the remarkable power of observing the behavior of an individual molecule, an individual nanoparticle, or biochemical reactions occurring in an individual cell. Exquisite details of chemical mechanisms and biological function that can only be inferred, at best, from measurements on a large ensemble, are often immediately transparent when observing single molecules and structures, and individual chemical reactions. A quarter of a century later, single-entity experimental methods impact all branches of science, medicine and engineering, and have transformed how analytical chemists design experiments to tease out fundamental and technologically relevant information from complex heterogeneous systems.

In this themed “Single Entities” issue of Analyst, 14 groups of investigators present new methods for analyzing complex biological chemistry within single cells, measuring and modifying transport in single nanopores, and studying the reactivity of single nanoparticles, as well as the cytotoxicity of nanoparticles. The common focus is on analytical instrumentation, protocols, and nanostructure fabrication for “single” analyses, but more importantly each article reports important and fascinating new insights into structure and reactivity that would likely have been missed in an ensemble-level investigation. The observant reader of this issue of the Analyst will obtain a true sense of the power of analytical chemistry at the “single entity” level.

Henry S. White, University of Utah, USA

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