Luminescent sensor improvements: Materials to techniques

Multiple approaches to improving luminescent sensor technology have been pursued. The first approach seeks novel sensor-polymer support systems to elucidate the significant, yet not fully characterized, role of polymer supports in sensor performance and to detect specific analytes including copper(II) ions and carbon dioxide. Both detection systems utilize luminescent ruthenium(II) complexes as the sensor molecule. The polymers used contain a hydrophobic binding region for the sensor molecule.; The first sensing model consisted of a sensor complex (Ru-cyclam = [Ru(Ph 2phen)2(4-cyclamCH2(4'-Me)bpy)]Cl 2 where Ph2phen = 4,7-diphenyl-1,10-phenanthroline, bpy = 2,2'-bipyridine, and cyclam = 1,4,8,11-tetraazacyclotetradecane), a quenching analyte (copper(II) ions), and a polymer support. The second sensing system was designed to measure carbon dioxide-induced pH changes. This model system consisted of a sensor complex ([Ru(Ph2phen)2(DEAM 2bpy)]2+ where DEAM2bpy = 4,4' -bis (diethylaminomethyl)-2,2' bipyridine), a phase transfer agent, and a polymer support.; To further the understanding of the gas diffusion measurements and interactions between sensor molecules and polymer supports, a computerized intensity-based diffusion coefficient instrument (CDI) was designed and constructed. Design considerations, a series of mathematical simulations, and experimental results for automated luminescence-based oxygen diffusion coefficient measurements are discussed.; Sensor technology can also be improved by modifying existing measurement methods. Gated phase-modulation (GPM) fluorometry was developed to measure lifetimes from relative long-lived samples without or with reduced errors from scattered light and short-lived fluorescences. The use of an offset time prior to gating the detector on mitigates errors from fluorescence bleed-through into the detection period or a slow excitation source turn off for relative long-lived samples. Theory and experimental results are presented.; An adaptation of GPM fluorimetry allows for self-referenced intensity measurements. A combination of theory and experimental results demonstrated the validity of GPM and its adaptation. As the concentration of the analyte changed, the corresponding sensor intensity changes can be quantified through several schemes including digitization of the signal and digital integration or AC methods. The adaptation requires the use of a reference emitter and an analyte-sensitive molecule with very different lifetimes. The fluctuations of the excitation source and any optical transmission changes are eliminated by ratioing the sensor emission to the reference emission.