Development of ultrasmall ion optodes for physiological measurements and supermolecules for intramolecular energy transfer.
Shortreed, Michael Robert
1996
Abstract
An optical sensor based on covalent immobilization (in a hydrogel) of a newly synthesized calcium-selective, long-wavelength, fluorescent indicator (Calcium Green) was constructed, with a response dynamic range optimal for physiological measurements. The working lifetime of this sensor was limited only by photobleaching of the indicator. The sensor had a calculated selectivity of $10\sp{-4.5}$ against magnesium and a rapid response time. An extension into the fluorescence regime of cation- and anion-selective correlated ion-transfer optodes was described which allowed miniaturization. Different sensor configurations were given, employing different lipophilic, fluorescent pH chromoionophores (Nile Blue derivatives), demonstrating the ability to improve the detection limit and tune the dynamic range. A number of sensors had working ranges covering physiological levels of sodium, potassium or chloride at physiological pH with excellent selectivity against many relevant ions. Mathematical relationships were developed for intensity, intensity ratios, and inner-filter effects permitting visualization on a single graph. Diffusion enhanced self-recovery from photobleaching was demonstrated on single-mode optical fibers with a 3.1 $\mu$m active region and on near-field scanning optical microscope light sources with 250 nm active region. The single-mode optode can be used for 30,000 measurements with only a 5% signal loss at a signal/noise $>$66. Theoretical, thermodynamic anion-optode equilibria formalisms were derived to understand the influence lipophilic ionic additives have on the anion optode response and selectivity behavior. Neutral and charged anion-carrier film configurations were described and tested for two anion ionophores with known modes of action, Ru(II)octaethylporphyrin and Nitrite Ionophore I. These film configurations were further tested using Co(III)tetraphenylporphyrin and In(III)octaethylporphyrin. For certain fractal-like phenylacetylene selected dendrimers both theory and experiment put the lowest excitation energies at the locus of the supermolecule, resulting in a completely symmetrical and ordered energy funnel. We designed and synthesized monodendrons with a perylene derivative at the locus which increases the photon yield by three orders of magnitude, demonstrating a directed, multi-step, molecular energy transport. The organosilane self-assembled-monolayer formation was studied. The method developed was based on second harmonic generation efficiency as a function of pH. The gas phase SAM formation is via direct attachment to the surface silyl groups confirming the standard model. The solution (hydrous or anhydrous) formation produces stilted monlayers with sparse links to the surface.Subjects
Development Energy Intramolecular Ion Measurements Optical Sensors Optodes Physiological Supermolecules Transfer Ultrasmall
Types
Thesis
Metadata
Show full item recordCollections
Remediation of Harmful Language
The University of Michigan Library aims to describe library materials in a way that respects the people and communities who create, use, and are represented in our collections. Report harmful or offensive language in catalog records, finding aids, or elsewhere in our collections anonymously through our metadata feedback form. More information at Remediation of Harmful Language.
Accessibility
If you are unable to use this file in its current format, please select the Contact Us link and we can modify it to make it more accessible to you.