Magnetic resonance contrast-enhancing agents whose effects are altered by electric fields

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7009750

Frank, S

Changes in the potential of membranes control or accompany numerous biological processes including information transfer in neuronal networks. Magnetic resonance imaging is essentially a non-invasive 3-dimensional imaging modality and could record changes in membrane potential if they were accompanied by changes in water proton relaxation rates in the vicinity of the membrane. Contrast-enhancing agents whose effects are changed by electric fields were developed. It may also be possible to develop magnetic resonance contrast agents that respond to changes in temperature, pH, light, or concentrations of certain ions and molecules, as all these changes in the environment are known to induce volume phase transitions in some polyelectrolyte gels. A polyelectrolyte gel, sodium polyacrylate, that undergoes a volume phase transition when an electric field is applied, was modified to make it magnetic by the incorporation of small superparamagnetic iron oxide particles into the polymer's network. A suspension of magnetic gel microparticles that shrunk when an electric field was applied also showed an increase in the transverse relaxation rate of the water. A similar change occurred when the magnetic gel microparticles were put in a 10% red blood cell suspension and the cells were hyperpolarized by adding valinomycin. These experiments should be extended to excitable cells, both in vitro and in vivo, including MRI experiments. Although the work concentrated on superparamagnetic-contrast agents, some preliminary work was carried out on Gd[sup 3+]-bound (paramagnetic) polyelectrolyte gel microparticles which showed a small decrease in the relaxation rate when an electric field was applied.

• Research Organization: Illinois Univ., Urbana, IL (United States)
• OSTI ID: 7009750
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400 -- Electrochemistry
550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
BODY
BRAIN
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CONTRAST MEDIA
DIAGNOSTIC TECHNIQUES
ELECTRIC FIELDS
IONIC POTENTIAL
MEMBRANES
NERVE CELLS
NERVOUS SYSTEM
NMR IMAGING
ORGANS
RELAXATION
SOMATIC CELLS