title: Differentiating between fluorescence-quenching metal ions with polyfluorophore sensors built on a DNA backbone.
abstract: A common problem in detecting metal ions with fluorescentchemosensors is the emission-suppressing effects of fluorescence-quenching metal ions. This quenching tendency makes it difficult to design sensors with turn-on signal, and differentiate between several metal ions that may yield a strong quenching response. To address these challenges, we investigate a new sensor design strategy, incorporating fluorophores and metal ligands as DNA base replacements in DNA-like oligomers, for generating a broader range of responses for quenching metal ions. The modular molecular design enabled rapid synthesis and discovery of sensors from libraries on PEG-polystyrene beads. Using this approach, water-soluble sensors 1-5 were identified as strong responders to a set of eight typically quenching metal ions (Co(2+), Ni(2+), Cu(2+), Hg(2+), Pb(2+), Ag(+), Cr(3+), and Fe(3+)). They were synthesized and characterized for sensing responses in solution. Cross-screening with the full set of metal ions showed that they have a wide variety of responses, including emission enhancements and red- and blue-shifts. The diversity of sensor responses allows as few as two sensors (1 and 2) to be used together to successfully differentiate these eight metals. As a test, a set of unknown metal ion solutions in blind studies were also successfully identified based on the response pattern of the sensors. The modular nature of the sensor design strategy suggests a broadly applicable approach to finding sensors for differentiating many different cations by pattern-based recognition, simply by varying the sequence and composition of ligands and fluorophores on a DNA synthesizer.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Tan
authors.forename: Su Jeong
authors.initials: SJ
authors.lastname: Kim
authors.forename: Eric T
authors.initials: ET
authors.lastname: Kool
mesh_terms: D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D008968:Molecular Conformation; D011092:Polyethylene Glycols / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D007477:Ions; D019216:Metals, Heavy; D011137:Polystyrenes; C103390:polyethylene glycol-polystyrene; D011092:Polyethylene Glycols; D004247:DNA