Ultra-small fluorescent metal nanoclusters: Synthesis and biological applications

Chemistries that Facilitate Nanotechnology Kim E. Sapsford,† W. Russ Algar, Lorenzo Berti, Kelly Boeneman Gemmill,‡ Brendan J. Casey,† Eunkeu Oh, Michael H. Stewart, and Igor L. Medintz*,‡ †Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States ‡Center for Bio/Molecular Science and Engineering Code 6900 and Division of Optical Sciences Code 5611, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States College of Science, George Mason University, 4400 University Drive, Fairfax, Virginia 22030, United States Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, California 95817, United States Sotera Defense Solutions, Crofton, Maryland 21114, United States

Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology.

Metal nanoclusters: New fluorescent probes for sensors and bioimaging

Silver nanoclusters are a class of fluorophores with attractive features, including brightness, photostability and subnanometer size. In this review we overview the different scaffolds that are used as stabilizer for silver nanoclusters (e.g. polymers, dendrimers, DNA oligomers, cryogenic noble gas matrixes, inorganic glasses, zeolites and nanoparticles), and we briefly discuss the recent advances.

Fluorescent silver nanoclusters

Though creation and characterization of water soluble luminescent silver nanodots were achieved only in the past decade, a large variety of emitters in diverse scaffolds have been reported. Photophysical properties approach those of semiconductor quantum dots, but relatively small sizes are retained. Because of these properties, silver nanodots are finding ever-expanding roles as probes and biolabels. In this critical review we revisit the studies on silver nanodots in inert environments and in aqueous solutions. The recent advances detailing their chemical and physical properties of silver nanodots are highlighted with an effort to decipher the relations between their chemical/photophysical properties and their structures. The primary results about their biological applications are discussed here as well, especially relating to their chemical and photophysical behaviours in biological environments (216 references).

Developing luminescent silver nanodots for biological applications

In this contribution, we report synthesis of luminescent Ag nanoclusters (NCs, 1 nm average diameter) directly conjugated to an enzyme, bovine pancreatic α-chymotrypsin (CHT). The structural characterization of Ag−CHT nanobioconjugates was done using steady-state UV−vis absorption/photoluminescence spectroscopy and high-resolution transmission electron microscopy. By use of the spherical jellium model, the emission energy of CHT-conjugated Ag NCs was correlated with the number of atoms in the cluster and was found to be almost consistent with the experimental result. To establish the conformational changes of the enzyme before and after the conjugation of Ag NCs, circular dichroism studies were performed. The functional integrity of the enzyme conjugated to Ag NCs was investigated by monitoring the enzymatic activity of Ag−CHT conjugates by using UV−vis absorption spectroscopy and compared with the unbound enzyme under similar experimental conditions. To confirm the conjugation of Ag NCs to CHT, we carrie...

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S. Shankara Narayanan and

Papers

Structural and Functional Characterization of Luminescent Silver−Protein Nanobioconjugates