Observation of reactions in single molecules/nanoparticles using light microscopy

Abstract

Recent techniques for direct observation of single molecules or nanoparticles provide methodologies for imaging the activation sites of heterogeneous catalysts (spatially resolved) and observing intermediates that are not visible in the ensemble average (temporally resolved). Accordingly, the primary challenge for related experiments is obtaining sufficient spatial and temporal resolutions for microscopic observation of the chemical reaction of interest. This review discusses recent advances in fluorescence—for example, total internal reflection fluorescence (TIRF)—and dark‐field microscopy—for example, imaging plasmonic probes—used for observing organic, inorganic, and biological reactions. The following key factors for microscopic observation of chemical reactions are discussed: (1) design of the chemical reaction and probe, (2) selection of microscope based on reaction's temporal information, and (3) use of machine learning algorithms to analyze the sequence imaging data. This review summarizes experimental techniques and detailed examples of reactions at the single molecule and nanoparticle level. Furthermore, it discusses avenues of development. These observations can guide the development of new and systematic methodological approaches for investigating important unsolved problems in chemistry.

Analysis of Phase Heterogeneity in Lipid Membranes Using Single-Molecule Tracking in Live Cells

“…When recently reported intermolecular interactions (e.g., protein–protein interactions), ,,, the heterogeneity of the lipid packing of the membrane, and the curvature of plasma membrane , are considered together, we may be able to understand the chemical reactions that occur in the plasma membrane more precisely. Furthermore, using parallel observation at the single-molecule level and systematic interpretation , with cellular signals in real time, e.g., kinase phosphorylation reporters, we may be able to answer long-standing questions on how the phase separation of cell membranes regulates cellular signals. We hope that lipid-MAP can be used as a basis for understanding membrane molecular organization, cell signaling, and cellular function in the future.…”

From Homogeneity to Turing Pattern: Kinetically Controlled Self-Organization of Transmembrane Protein

“…Next, we specifically labeled SNAP-tagged PLVAP in living cells using “gold nanoparticles (Au NPs) in which a monovalent oligonucleotide (ssDNA) was adjoined” as a probe and “benzylguanine (BG, ligand for SNAP-tag)-conjugated complementary ssDNA” as a linker , (Figure a and Figures S5 and S6). Then, the diffusive motion of each Au NP-labeled PLVAP was monitored under a dark-field (DF) microscope under the Y27632 or control condition (Figure b,c, Figure S6, and Movie S1). This DF imaging based on the plasmonic nanoparticles allowed for long-term tracking of individual proteins without perversion because of a z -axis change (Figure d).…”

Au nanoparticle‐catalyzed electron transfer from ammonia‐borane to Ru(NH3)63+ for sensitive biosensing

“…Metal nanoparticles (NPs) have been widely utilized as labels in affinity-based biosensors owing to their unique optical and catalytic properties, making them highly effective for signal amplification. [1][2][3][4][5] In particular, their high catalytic activities in some redox and hydrolysis reactions facilitate rapid generation of signaling species with minimal undesired background reactions. [6][7][8] This capability enables the achievement of low detection limits without the need for prolonged incubation periods.…”