Fluorescent Noble Metal Nanoclusters

Monday, Oct 22, 2012

2:00pm – 3:00pm

Wyss Institute, Room 521, 3 Blackfan Circle, Boston, MA 02115

Speaker:

• Jennifer Martinez, Ph.D.
• Scientist, Center for Integrated Nanotechnologies
• Science Thrust: Soft, Biological and Composite Nanomaterials

Host:

• Donald E. Ingber, M.D., Ph.D.
• Founding Director and Core Faculty Member, Wyss Institute for Biologically Inspired Engineering at Harvard University
• Judah Folkman Professor of Vascular Biology, Harvard Medical School and Children's Hospital Boston
• Professor of Bioengineering, Harvard School of Engineering and Applied Sciences
• Member of the Kavli Institute for Bionano Science and Technology

Few-atom noble metal nanoclusters are collections of small numbers of gold or silver atoms (typically 2-30 atoms) with physical sizes close to the Fermi wavelength of an electron (~0.5 nm for gold and silver). These nanoclusters are a missing link between the atomic and nanoparticle behavior of noble metals - exhibiting fluoresence emissions spanning the UV to near IR range. Fluorescent metal nanoclusters are gaining much interest because of their desirable photophysical properties, smaller size than quantum dots, and biocompatibility. As a compliment to quantum dots and molecular fluorophores, fluorescent metal nanoclusters have been produced using templates of dendrimers and polymers, small molecular ligands, or within biological materials of interest, such as DNA. Recently, we have synthesized and photophysically characterized Ag-nanoclusters (AgNCs), which were templated on DNA, with distinct and narrow excitation and emission profiles tuned to common laser lines. Intrinsically fluorescent recognition ligands have been created from chimera's of DNA that template AgNC and aptamers, for the specific and sensitive detection of proteins. More recently, we have deveoped a DNA detection probe (NanoCluster Beacon, NCB) that "lights up" upon target binding. In a separation-free assay, a single-to-background ration of up to 500 was demonstrated. In addition to eliminating the need to purify DNA nanocluster probes that do not bind targets, there is no need to remove the silver nanocluster precursors used during nanocluster formation. Further, chameleon NanoCluster Beacons have been developed that can identify single-nucleotide polymorphisms. Toward a better understanding of the structure of these families of fluorescent silver nanoclusters, we have begun EXAFS and SANS characterization. 

Contact information:

caitlin.wells@wyss.harvard.edu