Chemical Nose Sniffs Out Cancer

An array of nanoparticle-polymer sensors can detect cancer cells by sniffing out their physicochemical properties, reports Vincent M. Rotello of the University of Massachusetts, Amherst, and coworkers (Proc. Natl. Acad. Sci. USA 2009, 106, 10912). The team's chemical-nose approach distinguishes among normal, cancerous, and metastatic human breast cells, and even among analogous genetically identical mouse cells. To develop the sensor array, the researchers synthesized three versions of functionalized gold nanoparticles that bind differentially to phospholipids, carbohydrates, and integral membrane proteins on the surfaces of normal and cancer cells. The nanoparticles also bind noncovalently to the fluorescent polymer PPE-CO₂, an interaction that quenches the polymer's fluorescence. When the nanoparticle-polymer conjugates are added to cells growing in microwells, cell-surface components compete with PPE-CO₂ for nanoparticle binding. As the cells displace the polymer, fluorescence is restored and the researchers can detect differences in cell-surface composition by examining the fluorescence patterns of the three conjugates. Because the sensing strategy takes only minutes and requires no prior knowledge of cell-surface biomarkers, the method could have a major impact on cancer detection and treatment, Rotello says.