Fluorescent Probe Spots CO In Cells

A palladium-based molecular probe that forms a fluorescent compound upon reacting with carbon monoxide could allow scientists to study the gas’s nontoxic role in human biology, according to the probe’s developers (J. Am. Chem. Soc., DOI: 10.1021/ja307017b). Human cells produce CO, but no one knows why, says Christopher J. Chang of the University of California, Berkeley, who led the research team. To measure CO inside living cells in real time, Chang and his colleagues designed a probe based on palladium, because the metal readily binds CO. Upon binding CO, the probe reacts with the gas molecules, and as a result, CO is incorporated into the metal’s ligand to produce a fluorescent derivative. As a test of the probe, the researchers incubated kidney cells with or without a molecule that releases CO and then added the palladium compound to the medium. With a confocal microscope, the researchers observed that cells containing the CO-releasing molecule began to glow within 45 minutes, whereas the other cells remained dark. The probe detects CO levels in the low micromolar to high nanomolar range, Chang says.