Our laboratory has developed novel DNA-based "fluorescence nanobarcodes" that can rapidly identify multiple pathogens simultaneously in a single assay. These DNA nanobarcodes are formed from branched DNA via a novel self-assembly process. Each DNA nanobarcode carries a unique fluorescence color ratio – for example, 1 green dye and 2 red dyes (1G2R), or 4 green dyes and 1 red dye (4G1R). This allows us to distinguish among a large number of different targets using only two colors. Since our nanobarcodes are made entirely from DNA, they can be easily interfaced with biological systems. For instance we can use DNA nanobarcodes to detect pathogen biomarkers in order to diagnose infectious diseases.
DNA nanobarcodes are formed via a novel self-assembly process. Each DNA nanobarcode carries a unique fluorescence color ratio to identify a specific pathogen biomarker.
Bottom left: Microbead-based detection using green/red color ratios from DNA nanobarcodes. Each color ratio indicates the presence of a specific pathogen.
Y.G. Li, Y.D. Tseng, S.Y. Kwon, L. D'Espaux, J.S. Bunch, P.L. Mceuen, D. Luo, Controlled assembly of dendrimer-like DNA, Nature Materials 3 (2004) 38-42.
Y.G. Li, Y.T.H. Cu, D. Luo, Multiplexed detection of pathogen DNA with DNA-based fluorescence nanobarcodes, Nature Biotechnology 23 (2005) 885-889.
S.H. Um, J.B. Lee, S.Y. Kwon, Y. Li, D. Luo, Dendrimer-like DNA-based fluorescence nanobarcodes, Nature Protocols 1 (2006) 995-1000.
Our laboratory has also developed branched DNA structures with photo-crosslinkable capabilities – termed Anisotropic, Branched, Crosslinkable monomers (ABC monomers). These ABC monomers achieve highly sensitive detection via light-driven amplification. After brief UV exposure, monomers form large polymeric aggregates that are easy to detect. Each ABC monomer can also be labeled with fluorescence dyes, quantum dots, or nanoparticles for added functionality.
ABC monomers recognize and bind to specific target biomarkers. This recognition event is then amplified by a photoreaction, resulting in large polymeric aggregates. Amplification is achieved without any enzymes – only light is required.
Above: Fluorescence microscope image of polymeric aggregates, formed from ABC monomers. In the presence of target biomarker, ABC monomers form aggregates upon exposure to UV light (left). The resulting aggregates are easy to detect by a variety of approaches. In the absence of target, no aggregates form (right).
J.B. Lee, Y.H. Roh, S.H. Um, H. Funabashi, W.L Cheng, J.J. Cha, P. Kiatwuthinon, D.A. Muller, D. Luo, Multifunctional nanoarchitectures from DNA-based ABC monomers, Nature Nanotechnology 4 (2009) 430-436