—'Nano-Flares' Probe Cellular Activities “” Northwestern University chemists report fluorescence probes that can be used as transfection agents as well as tools for visualizing and quantifying RNA in living cells (J. Am. Chem. Soc., DOI: 10.1021/ja0776529). To make the probes, Chad A. Mirkin and colleagues functionalized gold nanoparticles with thiolated oligonucleotides and then hybridized them to cyanine fluorophores. Named "nano-flares" by the researchers, the cell-penetrating probes overcome many of the previous challenges of transforming a specific RNA-binding event into a fluorescent signal via sensitive, intracellular detection. For example, nano-flares don't require chemical chaperones to usher them inside the cell. These probes additionally exploit the highly efficient fluorescence-quenching properties of gold, are stable and sensitive in cellular environments, and exhibit a low background signal. The fluorescence signal correlates to the relative amount of mRNA in a cell. The probes demonstrated a 3.8-fold increase in fluorescence signal when binding synthetic targets and a 2.5-fold increase when binding the survivin gene in a line of human breast cancer cells.
December 03, 2007