This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Recently, there has been an extensive use of polymeric microspheres as a matrix for the slow release of drugs inside the body. To model and subsequently control this process, one requires tools for observing the drug distribution and monitoring the physical conditions within the sphere, after preparation, and during the release process. Currently the major tool used for such measurements is laser scanning confocal fluorescence microscopy, which employs fluorescent labeled drugs. The problems with this method are that it does not enable to penetrate deep into the sphere, it provides non-linear image intensity (due to unknown absorption and scattering coefficients in the sphere), and it cannot be employed easily during the in-vitro/in-vivo release process. Furthermore fluorescence does not have a good capability to quantify the porosity of the spheres, and the self diffusion tensor of the molecules in the sphere. ESR microscopy, however, which is a new magnetic resonance imaging method developed in our lab, has a potential of answering the problems and limitations of optical methods. This subproject is aimed at demonstrating an example for the additional information available through ESR microcopy. In this work, we have examined by ESR microscopy several types of polymer microspheres with a typical size of 100 microns, internalized with stable organic radicals. These microspheres were prepared for us at the University of Singapore in the group of Prof. C. H. Wang. We monitored, through our technique, the 3D radical distribution during the release process and measured the spatially resolved T2 of the radicals with a typical resolution of ~ 10 microns. We have found that T2 was significantly shorter inside the sphere and attributed this observation to an increased viscosity (probably due to the presence of poly-ethylene-glycol inside the sphere). Further investigations along these lines would help to explain the kinetics of the release process through current theories, and may enable the development of better methods of sphere preparation for more controlled release.

National Institute of Health (NIH)
National Center for Research Resources (NCRR)
Biotechnology Resource Grants (P41)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BCMB-K (40))
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Cornell University
Schools of Arts and Sciences
United States
Zip Code
Jain, Rinku; Vanamee, Eva S; Dzikovski, Boris G et al. (2014) An iron-sulfur cluster in the polymerase domain of yeast DNA polymerase ?. J Mol Biol 426:301-8
Pratt, Ashley J; Shin, David S; Merz, Gregory E et al. (2014) Aggregation propensities of superoxide dismutase G93 hotspot mutants mirror ALS clinical phenotypes. Proc Natl Acad Sci U S A 111:E4568-76
Georgieva, Elka R; Borbat, Peter P; Ginter, Christopher et al. (2013) Conformational ensemble of the sodium-coupled aspartate transporter. Nat Struct Mol Biol 20:215-21
Airola, Michael V; Sukomon, Nattakan; Samanta, Dipanjan et al. (2013) HAMP domain conformers that propagate opposite signals in bacterial chemoreceptors. PLoS Biol 11:e1001479
Airola, Michael V; Huh, Doowon; Sukomon, Nattakan et al. (2013) Architecture of the soluble receptor Aer2 indicates an in-line mechanism for PAS and HAMP domain signaling. J Mol Biol 425:886-901
Sun, Yan; Zhang, Ziwei; Grigoryants, Vladimir M et al. (2012) The internal dynamics of mini c TAR DNA probed by electron paramagnetic resonance of nitroxide spin-labels at the lower stem, the loop, and the bulge. Biochemistry 51:8530-41
Yu, Renyuan Pony; Darmon, Jonathan M; Hoyt, Jordan M et al. (2012) High-Activity Iron Catalysts for the Hydrogenation of Hindered, Unfunctionalized Alkenes. ACS Catal 2:1760-1764
Dzikovski, Boris; Tipikin, Dmitriy; Freed, Jack (2012) Conformational distributions and hydrogen bonding in gel and frozen lipid bilayers: a high frequency spin-label ESR study. J Phys Chem B 116:6694-706
Gaffney, Betty J; Bradshaw, Miles D; Frausto, Stephen D et al. (2012) Locating a lipid at the portal to the lipoxygenase active site. Biophys J 103:2134-44
Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey et al. (2012) Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies. J Am Chem Soc 134:9209-18

Showing the most recent 10 out of 72 publications