title: Light-switching excimer probes for rapid protein monitoring in complex biological fluids.
abstract: Quantitative protein bioanalysis in complex biological fluids presents considerable challenges in biological studies and disease diagnosis. The major obstacles are the background signals from both the probe and the biological fluids where the proteins reside. We have molecularly engineered light-switching excimer aptamer probes for rapid and sensitive detection of a biomarker protein, platelet-derived growth factor (PDGF). Labeled with one pyrene at each end, the aptamer switches its fluorescence emission from approximately 400 nm (pyrene monomer) to 485 nm (pyrene excimer) upon PDGF binding. This fluorescence wavelength change from monomer to excimer emission is a result of aptamer conformation rearrangement induced by target binding. The excimer probe is able to effectively detect picomolar PDGF in homogeneous solutions. Because the excimer has a much longer fluorescence lifetime (approximately 40 ns) than that of the background (approximately 5 ns), time-resolved measurements were used to eliminate the biological background. We thus were able to detect PDGF in a cell sample quantitatively without any sample pretreatment. This molecular engineering strategy can be used to develop other aptamer probes for protein monitoring. Combined with lifetime-based measurements and molecular engineering, light-switching excimer aptamer probes hold great potential in protein analysis for biomedical studies.
authors.affiliation: Center for Research at Bio/Nano Interface, Department of Chemistry, University of Florida Genetics Institute, Gainesville, FL 32611, USA.
authors.forename: Chaoyong James
authors.initials: CJ
authors.lastname: Yang
authors.forename: Steffen
authors.initials: S
authors.lastname: Jockusch
authors.forename: Marie
authors.initials: M
authors.lastname: Vicens
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Turro
authors.forename: Weihong
authors.initials: W
authors.lastname: Tan
mesh_terms: D001826:Body Fluids / Q000737:chemistry*; D002616:Chemical Engineering / Q000379:methods; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D005456:Fluorescent Dyes; D015336:Molecular Probe Techniques; D009841:Oligonucleotides; D010982:Platelet-Derived Growth Factor / Q000302:isolation & purification; D011506:Proteins / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D009841:Oligonucleotides; D010982:Platelet-Derived Growth Factor; D011506:Proteins