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Chemical and Biomolecular Engineering

U of I researchers create new tools for fluorescence microscopy and imaging

By Rick Kubetz, writer/editor, Engineering Communications Office

Researchers from the University of Illinois at Urbana-Champaign have developed a new class of fluorescent probes for studying biological processes at the single molecule level.

Recent advances in fluorescence imaging and single-molecule fluorescence microscopy (SMFM) have enabled the direct observation of biological processes at the molecular level. Fluorescence imaging techniques critically rely on bright and photostable fluorescent probes with robust photophysical properties.
Research image from Assistant Professor Charles Schroeder
Research image from Assistant Professor Charles Schroeder.


“Overall, there is a strong need for development of advanced molecular-scale probes for fluorescence imaging,” explained Charles M. Schroeder, assistant professor in the Department of Chemical and Biomolecular Engineering at Illinois.“In this work, we synthesized fluorescent dendritic nanoprobes (FDNs), which show enhanced brightness and extended photostability compared to small molecule fluorescent dyes. In addition, FDN probes can be readily attached to target biomolecules such as proteins and antibodies, thereby facilitating application to biological imaging.”

The current project was a collaboration between Schroeder’s lab and Chemistry Professor John Katzenellenbogen’s research group on campus. The article, “Dendrimer Probes for Enhanced Photostability and Localization in Fluorescence Imaging,” describing their work appears in the April 2013 edition of Biophysical Journal.

Dendrimers are polymers having highly regular branched structures with large numbers of terminal functional groups. Compared to linear macromolecules, dendrimers can be synthesized with controlled shapes and nearly monodisperse sizes which is a key advantage for fluorescent probes used for biological labeling. Over the past several years, dendrimers have been used for gene and drug delivery and diagnostic applications via live cell or animal imaging.

“Polymer-based dendrimer nanoconjugates hold strong potential as versatile fluorescent probes due to an intrinsic capacity for tailored spectral properties such as brightness and emission wavelength,” said Younghoon Kim, a postdoctoral research associate in bioengineering, and first author for the article.

Biocompatible probes with small dimensions are critically required for biological imaging and high-resolution fluorescence microscopy.

Research image from Assistant Professor Charles Schroeder
Research image from Assistant Professor Charles Schroeder

“In this work, we synthesized FDNs to contain multiple covalently linked organic dyes on nanometer-sized macromolecules,” Kim added. “Dye-conjugated dendrimers are compact in size and show superior spectral properties compared to single organic dyes. To our knowledge, this is a new class of molecular probes based on dye-conjugated dendrimers for fluorescence imaging and single-molecule fluorescence microscopy.”

“Our new class of fluorescent probes offer a variety of advantages for imaging, which will enable new studies molecular and cellular biology,” added Schroeder, who also holds faculty appointments in chemistry, materials science and engineering, and at the Center for Biophysics and Computational Biology. The work has led to a patent application for a new class of fluorescent reporters for fluorescence microscopy and imaging.

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